Diff of /xvidcore/src/plugins/plugin_2pass2.c

-revision 1.1.2.21, Tue Jun 10 10:12:24 2003 UTC
+revision 1.10.2.1, Tue Dec 28 19:19:57 2010 UTC
 Line 1
  /******************************************************************************
   *
-  *  XviD Bit Rate Controller Library
+  *  Xvid Bit Rate Controller Library
   *  - VBR 2 pass bitrate controller implementation -
   *
-  *  Copyright (C)      2002 Foxer <email?>
+  *  Copyright (C)      2002 Benjamin Lambert <foxer@hotmail.com>
   *                     2002 Dirk Knop <dknop@gwdg.de>
   *                2002-2003 Edouard Gomez <ed.gomez@free.fr>
   *                     2003 Pete Ross <pross@xvid.org>
   *
   *  This curve treatment algorithm is the one originally implemented by Foxer
-  *  and tuned by Dirk Knop for the XviD vfw frontend.
+  *  and tuned by Dirk Knop for the Xvid vfw frontend.
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
 Line 29
   *
   *****************************************************************************/
+ #define BQUANT_PRESCALE
+ #undef COMPENSATE_FORMULA
+ /* forces second pass not to be bigger than first */
+ #undef PASS_SMALLER
+ /* automatically alters overflow controls (strength and improvement/degradation)
+         to fight most common problems without user's knowladge */
+ #define SMART_OVERFLOW_SETTING
  #include <stdio.h>
  #include <math.h>
  #include <limits.h>
-Line 37
+Line 47
  #include "../image/image.h"
  /*****************************************************************************
-  * Some constants
+  * Some default settings
   ****************************************************************************/
  #define DEFAULT_KEYFRAME_BOOST 0
- #define DEFAULT_PAYBACK_METHOD XVID_PAYBACK_PROP
+ #define DEFAULT_OVERFLOW_CONTROL_STRENGTH 10
- #define DEFAULT_BITRATE_PAYBACK_DELAY 250
  #define DEFAULT_CURVE_COMPRESSION_HIGH 0
  #define DEFAULT_CURVE_COMPRESSION_LOW 0
- #define DEFAULT_MAX_OVERFLOW_IMPROVEMENT 60
+ #define DEFAULT_MAX_OVERFLOW_IMPROVEMENT 10
- #define DEFAULT_MAX_OVERFLOW_DEGRADATION 60
+ #define DEFAULT_MAX_OVERFLOW_DEGRADATION 10
  /* Keyframe settings */
- #define DEFAULT_KFTRESHOLD 10
  #define DEFAULT_KFREDUCTION 20
- #define DEFAULT_MIN_KEY_INTERVAL 1
+ #define DEFAULT_KFTHRESHOLD 1
+ /*****************************************************************************
+  * Some default constants (can be tuned)
+  ****************************************************************************/
+ /* Specify the invariant part of the headers bits (header+MV)
+  * as  hlength/cst */
+ #define INVARIANT_HEADER_PART_IVOP 1 /* factor 1.0f   */
+ #define INVARIANT_HEADER_PART_PVOP 2 /* factor 0.5f   */
+ #define INVARIANT_HEADER_PART_BVOP 8 /* factor 0.125f */
  /*****************************************************************************
   * Structures
-Line 63
+Line 81
      int quant;              /* first pass quant */
          int blks[3];                    /* k,m,y blks */
      int length;             /* first pass length */
+         int invariant;          /* what we assume as being invariant between the two passes, it's a sub part of header + MV bits */
      int scaled_length;      /* scaled length */
-     int desired_length;     /* desired length; calcuated during encoding */
+         int desired_length;     /* desired length; calculated during encoding */
+         int error;
      int zone_mode;   /* XVID_ZONE_xxx */
      double weight;
- } stat_t;
+ } twopass_stat_t;
  /* Context struct */
  typedef struct
  {
      xvid_plugin_2pass2_t param;
-     /* constant statistical data */
+         /*----------------------------------
-         int num_frames;
+          * constant statistical data
-         int num_keyframes;
+          *--------------------------------*/
-         uint64_t target;        /* target filesize */
-         int count[3];   /* count of each frame types */
-         uint64_t tot_length[3];  /* total length of each frame types */
-         double avg_length[3];   /* avg */
-         int min_length[3];  /* min frame length of each frame types */
-         uint64_t tot_scaled_length[3];  /* total scaled length of each frame type */
-         int max_length;     /* max frame size */
-         /* zone statistical data */
+         /* Number of frames of the sequence */
-         double avg_weight;  /* average weight */
+         int num_frames;
-         int64_t tot_quant;   /* total length used by XVID_ZONE_QUANT zones */
+         /* Number of Intra frames of the sequence */
+         int num_keyframes;
-         double curve_comp_scale;
+         /* Target filesize to reach */
-         double movie_curve;
+         uint64_t target;
-         /* dynamic */
+         /* Count of each frame types */
+         int count[3];
+         /* Total length of each frame types (1st pass) */
+         uint64_t tot_length[3];
+         uint64_t tot_invariant[3];
+         /* Average length of each frame types (used first for 1st pass data and
+          * then for scaled averages */
+         double avg_length[3];
+         /* Minimum frame length allowed for each frame type */
+         int min_length[3];
+         /* Total bytes per frame type once the curve has been scaled
+          * NB: advanced parameters do not change this value. This field
+          *     represents the total scaled w/o any advanced settings */
+         uint64_t tot_scaled_length[3];
+         /* Maximum observed frame size observed during the first pass, the RC
+          * will try tp force all frame sizes in the second pass to be under that
+          * limit */
+         int max_length;
+         /*----------------------------------
+          * Zones statistical data
+          *--------------------------------*/
+         /* Total length used by XVID_ZONE_QUANT zones */
+         uint64_t tot_quant;
+         uint64_t tot_quant_invariant;
+         /* Holds the total amount of frame bytes, zone weighted (only scalable
+          * part of frame bytes) */
+         uint64_t tot_weighted;
+         /*----------------------------------
+          * Advanced settings helper ratios
+          *--------------------------------*/
+         /* This the ratio that has to be applied to all p/b frames in order
+          * to reserve/retrieve bits for/from keyframe boosting and consecutive
+          * keyframe penalty */
+         double pb_iboost_tax_ratio;
+         /* This the ratio to apply to all b/p frames in order to respect the
+          * assymetric curve compression while respecting a target filesize
+          * NB: The assymetric delta gain has to be computed before this ratio
+          *     is applied, and then the delta is added to the scaled size */
+         double assymetric_tax_ratio;
+         /*----------------------------------
+          * Data from the stats file kept
+          * into RAM for easy access
+          *--------------------------------*/
+         /* Array of keyframe locations
+          * eg: rc->keyframe_locations[100] returns the frame number of the 100th
+          *     keyframe */
          int * keyframe_locations;
-         stat_t * stats;
+         /* Index of the last keyframe used in the keyframe_location */
+         int KF_idx;
+         /* Array of all 1st pass data file -- see the twopass_stat_t structure
+          * definition for more details */
+         twopass_stat_t * stats;
+         /*----------------------------------
+          * Hysteresis helpers
+          *--------------------------------*/
+         /* This field holds the int2float conversion errors of each quant per
+          * frame type, this allow the RC to keep track of rouding error and thus
+          * increase or decrease the chosen quant according to this residue */
          double quant_error[3][32];
-         int quant_count[32];
+         /* This fields stores the count of each quant usage per frame type
+          * No real role but for debugging */
+         int quant_count[3][32];
+         /* Last valid quantizer used per frame type, it allows quantizer
+          * increament/decreament limitation in order to avoid big image quality
+          * "jumps" */
          int last_quant[3];
-         double curve_comp_error;
+         /*----------------------------------
-         int overflow;
+          * Overflow control
-         int KFoverflow;
+          *--------------------------------*/
-         int KFoverflow_partial;
-         int KF_idx;
+         /* Current overflow that has to be distributed to p/b frames */
+         double overflow;
+         /* Total overflow for keyframes -- not distributed directly */
+         double KFoverflow;
+         /* Amount of keyframe overflow to introduce to the global p/b frame
+          * overflow counter at each encoded frame */
+         double KFoverflow_partial;
+         /* Unknown ???
+          * ToDo: description */
          double fq_error;
+         int min_quant; /* internal minimal quant, prevents wrong quants from being used */
+         /*----------------------------------
+          * Debug
+          *--------------------------------*/
+         double desired_total;
+         double real_total;
+         int scaled_frames;
  } rc_2pass2_t;
-Line 132
+Line 242
  {
      switch(opt) {
      case XVID_PLG_INFO :
+         case XVID_PLG_FRAME :
          return 0;
      case XVID_PLG_CREATE :
-Line 155
+Line 266
   ****************************************************************************/
  /* First a few local helping function prototypes */
- static  int det_stats_length(rc_2pass2_t * rc, char * filename);
+ static  int statsfile_count_frames(rc_2pass2_t * rc, char * filename);
- static  int load_stats(rc_2pass2_t *rc, char * filename);
+ static  int statsfile_load(rc_2pass2_t *rc, char * filename);
  static void zone_process(rc_2pass2_t *rc, const xvid_plg_create_t * create);
- static void internal_scale(rc_2pass2_t *rc);
+ static void first_pass_stats_prepare_data(rc_2pass2_t * rc);
- static void pre_process0(rc_2pass2_t * rc);
+ static void first_pass_scale_curve_internal(rc_2pass2_t *rc);
- static void pre_process1(rc_2pass2_t * rc);
+ static void scaled_curve_apply_advanced_parameters(rc_2pass2_t * rc);
+ static  int check_curve_for_vbv_compliancy(rc_2pass2_t * rc, const float fps);
+ static  int scale_curve_for_vbv_compliancy(rc_2pass2_t * rc, const float fps);
+ #if 0
+ static void stats_print(rc_2pass2_t * rc);
+ #endif
  /*----------------------------------------------------------------------------
   *--------------------------------------------------------------------------*/
-Line 176
+Line 292
      if (rc == NULL)
          return XVID_ERR_MEMORY;
-     rc->param = *param;
+         /* v1.0.x */
+         rc->param.version = param->version;
+         rc->param.bitrate = param->bitrate;
+         rc->param.filename = param->filename;
+         rc->param.keyframe_boost = param->keyframe_boost;
+         rc->param.curve_compression_high = param->curve_compression_high;
+         rc->param.curve_compression_low = param->curve_compression_low;
+         rc->param.overflow_control_strength = param->overflow_control_strength;
+         rc->param.max_overflow_improvement = param->max_overflow_improvement;
+         rc->param.max_overflow_degradation = param->max_overflow_degradation;
+         rc->param.kfreduction = param->kfreduction;
+         rc->param.kfthreshold = param->kfthreshold;
+         rc->param.container_frame_overhead = param->container_frame_overhead;
+         if (XVID_VERSION_MINOR(param->version) >= 1) {
+                 rc->param.vbv_size = param->vbv_size;
+                 rc->param.vbv_initial = param->vbv_initial;
+                 rc->param.vbv_maxrate = param->vbv_maxrate;
+                 rc->param.vbv_peakrate = param->vbv_peakrate;
+         }else{
+                 rc->param.vbv_size =
+                 rc->param.vbv_initial =
+                 rc->param.vbv_maxrate =
+                 rc->param.vbv_peakrate = 0;
+         }
-         /*
+         /* Initialize all defaults */
-          * Initialize all defaults
-          */
  #define _INIT(a, b) if((a) <= 0) (a) = (b)
      /* Let's set our defaults if needed */
          _INIT(rc->param.keyframe_boost, DEFAULT_KEYFRAME_BOOST);
-         _INIT(rc->param.payback_method, DEFAULT_PAYBACK_METHOD);
+         _INIT(rc->param.overflow_control_strength, DEFAULT_OVERFLOW_CONTROL_STRENGTH);
-         _INIT(rc->param.bitrate_payback_delay, DEFAULT_BITRATE_PAYBACK_DELAY);
      _INIT(rc->param.curve_compression_high, DEFAULT_CURVE_COMPRESSION_HIGH);
      _INIT(rc->param.curve_compression_low, DEFAULT_CURVE_COMPRESSION_LOW);
      _INIT(rc->param.max_overflow_improvement, DEFAULT_MAX_OVERFLOW_IMPROVEMENT);
      _INIT(rc->param.max_overflow_degradation,  DEFAULT_MAX_OVERFLOW_DEGRADATION);
      /* Keyframe settings */
-         _INIT(rc->param.kftreshold, DEFAULT_KFTRESHOLD);
      _INIT(rc->param.kfreduction, DEFAULT_KFREDUCTION);
-     _INIT(rc->param.min_key_interval, DEFAULT_MIN_KEY_INTERVAL);
+         _INIT(rc->param.kfthreshold, DEFAULT_KFTHRESHOLD);
  #undef _INIT
          /* Initialize some stuff to zero */
-         for(i=0; i<32; i++) rc->quant_count[i] = 0;
          for(i=0; i<3; i++) {
                  int j;
-                 for (j=0; j<32; j++)
+                 for (j=0; j<32; j++) {
                          rc->quant_error[i][j] = 0;
+                         rc->quant_count[i][j] = 0;
+                 }
          }
-         for (i=0; i<3; i++)
+         for (i=0; i<3; i++) rc->last_quant[i] = 0;
-                 rc->last_quant[i] = 0;
          rc->fq_error = 0;
+         rc->min_quant = 1;
+         rc->scaled_frames = 0;
-         /* Count frames in the stats file */
+         /* Count frames (and intra frames) in the stats file, store the result into
-         if (!det_stats_length(rc, param->filename)) {
+          * the rc structure */
-                 DPRINTF(XVID_DEBUG_RC,"ERROR: fopen %s failed\n", param->filename);
+         if (statsfile_count_frames(rc, param->filename) == -1) {
+                 DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- ERROR: fopen %s failed\n", param->filename);
                  free(rc);
-                 return XVID_ERR_FAIL;
+                 return(XVID_ERR_FAIL);
          }
      /* Allocate the stats' memory */
-         if ((rc->stats = malloc(rc->num_frames * sizeof(stat_t))) == NULL) {
+         if ((rc->stats = malloc(rc->num_frames * sizeof(twopass_stat_t))) == NULL) {
          free(rc);
-         return XVID_ERR_MEMORY;
+                 return(XVID_ERR_MEMORY);
      }
-     /*
+         /* Allocate keyframes location's memory
-          * Allocate keyframes location's memory
+          * PS: see comment in pre_process0 for the +1 location requirement */
-          * PS: see comment in pre_process0 for the +1 location requirement
-          */
          rc->keyframe_locations = malloc((rc->num_keyframes + 1) * sizeof(int));
          if (rc->keyframe_locations == NULL) {
                  free(rc->stats);
                  free(rc);
-                 return XVID_ERR_MEMORY;
+                 return(XVID_ERR_MEMORY);
          }
-         if (!load_stats(rc, param->filename)) {
+         /* Load the first pass stats */
-                 DPRINTF(XVID_DEBUG_RC,"ERROR: fopen %s failed\n", param->filename);
+         if (statsfile_load(rc, param->filename) == -1) {
+                 DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- ERROR: fopen %s failed\n", param->filename);
                  free(rc->keyframe_locations);
                  free(rc->stats);
                  free(rc);
-Line 245
+Line 382
          /* Compute the target filesize */
      if (rc->param.bitrate<0) {
-         /* if negative, bitrate equals the target (int kbytes) */
+                 /* if negative, bitrate equals the target (in kbytes) */
-         rc->target = (-rc->param.bitrate) * 1024;
+                 rc->target = ((uint64_t)(-rc->param.bitrate)) * 1024;
      }else if (rc->num_frames  < create->fbase/create->fincr) {
                  /* Source sequence is less than 1s long, we do as if it was 1s long */
                  rc->target = rc->param.bitrate / 8;
-Line 259
+Line 395
                          ((uint64_t)create->fbase * 8);
          }
-         DPRINTF(XVID_DEBUG_RC, "Frame rate: %d/%d (%ffps)\n",
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Frame rate: %d/%d (%ffps)\n",
                          create->fbase, create->fincr,
                          (double)create->fbase/(double)create->fincr);
-         DPRINTF(XVID_DEBUG_RC, "Number of frames: %d\n", rc->num_frames);
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Number of frames: %d\n", rc->num_frames);
-         DPRINTF(XVID_DEBUG_RC, "Target bitrate: %ld\n", rc->param.bitrate);
+         if(rc->param.bitrate>=0)
-         DPRINTF(XVID_DEBUG_RC, "Target filesize: %lld\n", rc->target);
+                 DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Target bitrate: %ld\n", rc->param.bitrate);
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Target filesize: %lld\n", rc->target);
          /* Compensate the average frame overhead caused by the container */
          rc->target -= rc->num_frames*rc->param.container_frame_overhead;
-         DPRINTF(XVID_DEBUG_RC, "Container Frame overhead: %d\n", rc->param.container_frame_overhead);
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Container Frame overhead: %d\n", rc->param.container_frame_overhead);
-         DPRINTF(XVID_DEBUG_RC, "Target filesize (after container compensation): %lld\n", rc->target);
+         if(rc->param.container_frame_overhead)
+                 DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- New target filesize after container compensation: %lld\n", rc->target);
+         /* When bitrate is not given it means it has been scaled by an external
+          * application */
+         if (rc->param.bitrate) {
+                 /* Apply zone settings
+                  * - set rc->tot_quant which represents the total num of bytes spent in
+                  *   fixed quant zones
+                  * - set rc->tot_weighted which represents the total amount of bytes
+                  *   spent in normal or weighted zones in first pass (normal zones can
+                  *   be considered weight=1)
+                  * - set rc->tot_quant_invariant which represents the total num of bytes
+                  *   spent in fixed quant zones for headers */
+                 zone_process(rc, create);
+         } else {
+                 /* External scaling -- zones are ignored */
+                 for (i=0;i<rc->num_frames;i++) {
+                         rc->stats[i].zone_mode = XVID_ZONE_WEIGHT;
+                         rc->stats[i].weight = 1.0;
+                 }
+                 rc->tot_quant = 0;
+         }
-         /*
+         /* Gathers some information about first pass stats:
-          * First data pre processing:
           *  - finds the minimum frame length for each frame type during 1st pass.
           *     rc->min_size[]
           *  - determines the maximum frame length observed (no frame type distinction).
-Line 280
+Line 438
           *  - count how many times each frame type has been used.
           *     rc->count[]
           *  - total bytes used per frame type
-          *     rc->total[]
+          *     rc->tot_length[]
+          *  - total bytes considered invariant between the 2 passes
           *  - store keyframe location
           *     rc->keyframe_locations[]
           */
-         pre_process0(rc);
+         first_pass_stats_prepare_data(rc);
-         /*
+         /* If we have a user bitrate, it means it's an internal curve scaling */
-          * When bitrate is not given it means it has been scaled by an external
-          * application
-          */
          if (rc->param.bitrate) {
-                 /* Apply zone settings */
+                 /* Perform internal curve scaling */
-                 zone_process(rc, create);
+                 first_pass_scale_curve_internal(rc);
-                 /* Perform curve scaling */
-                 internal_scale(rc);
-         } else {
-                 /* External scaling -- zones are ignored */
-                 for (i=0;i<rc->num_frames;i++) {
-                         rc->stats[i].zone_mode = XVID_ZONE_WEIGHT;
-                         rc->stats[i].weight = 1.0;
                  }
-                 rc->avg_weight = 1.0;
-                 rc->tot_quant = 0;
+         /* Apply advanced curve options, and compute some parameters in order to
+          * shape the curve in the BEFORE/AFTER pair of functions */
+         scaled_curve_apply_advanced_parameters(rc);
+         /* Check curve for VBV compliancy and rescale if necessary */
+ #ifdef VBV_FORCE
+         if (rc->param.vbv_size==0) {
+                 rc->param.vbv_size      =  3145728;
+                 rc->param.vbv_initial   =  2359296;
+                 rc->param.vbv_maxrate   =  4854000;
+                 rc->param.vbv_peakrate  =  8000000;
+         }
+ #endif
+         /* vbv_size==0 switches VBV check off */
+         if (rc->param.vbv_size > 0)  {
+                 const float fps = (float)((double)create->fbase/(double)create->fincr);
+                 int status = check_curve_for_vbv_compliancy(rc, fps);
+                 if (status) {
+                         DPRINTF(XVID_DEBUG_RC, "[xvid rc] Underflow detected - Scaling Curve for compliancy.\n");
          }
-         pre_process1(rc);
+                 status = scale_curve_for_vbv_compliancy(rc, fps);
+                 if (status == 0) {
+                         DPRINTF(XVID_DEBUG_RC, "[xvid rc] VBV compliant curve scaling done.\n");
+                 } else {
+                         DPRINTF(XVID_DEBUG_RC, "[xvid rc] VBV compliant curve scaling impossible.\n");
+                 }
+         }
          *handle = rc;
          return(0);
  }
-Line 317
+Line 492
  static int
  rc_2pass2_destroy(rc_2pass2_t * rc, xvid_plg_destroy_t * destroy)
  {
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- target_total:%lld desired_total:%.2f (%.2f%%) actual_total:%.2f (%.2f%%)\n",
+                         rc->target,
+                         rc->desired_total,
+*rc->desired_total/(double)rc->target,
+                         rc->real_total,
+*rc->real_total/(double)rc->target);
      free(rc->keyframe_locations);
      free(rc->stats);
          free(rc);
-Line 329
+Line 511
  static int
  rc_2pass2_before(rc_2pass2_t * rc, xvid_plg_data_t * data)
  {
-         stat_t * s = &rc->stats[data->frame_num];
+         twopass_stat_t * s = &rc->stats[data->frame_num];
-         int overflow;
-         int desired;
          double dbytes;
-         double curve_temp;
          double scaled_quant;
+         double overflow;
          int capped_to_max_framesize = 0;
-         /*
+         /* This function is quite long but easy to understand. In order to simplify
-          * This function is quite long but easy to understand. In order to simplify
+          * the code path (a bit), we treat 3 cases that can return immediatly. */
-          * the code path (a bit), we treat 3 cases that can return immediatly.
-          */
          /* First case: Another plugin has already set a quantizer */
      if (data->quant > 0)
                  return(0);
-         /* Second case: We are in a Quant zone */
+         /* Second case: insufficent stats data
+          * We can't guess much what we should do, let core decide all alone */
+         if (data->frame_num >= rc->num_frames) {
+                 DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- stats file too short (now processing frame %d)",
+                         data->frame_num);
+                 return(0);
+         }
+         /* Third case: We are in a Quant zone
+          * Quant zones must just ensure we use the same settings as first pass
+          * So set the quantizer and the type */
          if (s->zone_mode == XVID_ZONE_QUANT) {
+                 /* Quant stuff */
                  rc->fq_error += s->weight;
                  data->quant = (int)rc->fq_error;
                  rc->fq_error -= data->quant;
+                 /* The type stuff */
+                 data->type = s->type;
+                 /* The only required data for AFTER step is this one for the overflow
+                  * control */
                  s->desired_length = s->length;
                  return(0);
          }
-         /* Third case: insufficent stats data */
-         if (data->frame_num >= rc->num_frames)
-                 return 0;
-         /* XXX: why by 8 */
+         /*************************************************************************/
-         overflow = rc->overflow / 8;
+         /*************************************************************************/
+         /*************************************************************************/
-         /*
+         /*-------------------------------------------------------------------------
-          * The rc->overflow field represents the overflow in current scene (between two
+          * Frame bit allocation first part
-          * IFrames) so we must not forget to reset it if we are entering a new scene
+          *
-          */
+          * First steps apply user settings, just like it is done in the theoritical
-         if (s->type == XVID_TYPE_IVOP)
+          * scaled_curve_apply_advanced_parameters
-                 overflow = 0;
+          *-----------------------------------------------------------------------*/
-         desired = s->scaled_length;
+         /* Set desired to what we are wanting to obtain for this frame */
+         dbytes = (double)s->scaled_length;
-         dbytes = desired;
+         /* IFrame user settings*/
-         if (s->type == XVID_TYPE_IVOP)
+         if (s->type == XVID_TYPE_IVOP) {
-                 dbytes += desired * rc->param.keyframe_boost / 100;
+                 /* Keyframe boosting -- All keyframes benefit from it */
-         dbytes /= rc->movie_curve;
+                 dbytes += dbytes*rc->param.keyframe_boost / 100;
-         /*
+ #if 0 /* ToDo: decide how to apply kfthresholding */
-          * Apply user's choosen Payback method. Payback helps bitrate to follow the
+ #endif
-          * scaled curve "paying back" past errors in curve previsions.
-          */
-         if (rc->param.payback_method == XVID_PAYBACK_BIAS) {
-                 desired = (int)(rc->curve_comp_error / rc->param.bitrate_payback_delay);
          } else {
-                 desired = (int)(rc->curve_comp_error * dbytes /
-                                                 rc->avg_length[s->type-1] / rc->param.bitrate_payback_delay);
-                 if (labs(desired) > fabs(rc->curve_comp_error))
+                 /* P/S/B frames must reserve some bits for iframe boosting */
-                         desired = (int)rc->curve_comp_error;
+                 dbytes *= rc->pb_iboost_tax_ratio;
+                 /* Apply assymetric curve compression */
+                 if (rc->param.curve_compression_high || rc->param.curve_compression_low) {
+                         double assymetric_delta;
+                         /* Compute the assymetric delta, this is computed before applying
+                          * the tax, as done in the pre_process function */
+                         if (dbytes > rc->avg_length[s->type-1])
+                                 assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_high / 100.0;
+                         else
+                                 assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_low  / 100.0;
+                         /* Now we must apply the assymetric tax, else our curve compression
+                          * would not give a theoritical target size equal to what it is
+                          * expected */
+                         dbytes *= rc->assymetric_tax_ratio;
+                         /* Now we can add the assymetric delta */
+                         dbytes += assymetric_delta;
          }
+         }
+         /* That is what we would like to have -- Don't put that chunk after
+          * overflow control, otherwise, overflow is counted twice and you obtain
+          * half sized bitrate sequences */
+         s->desired_length  = (int)dbytes;
+         rc->desired_total += dbytes;
-         rc->curve_comp_error -= desired;
+         /*------------------------------------------------------------------------
+          * Frame bit allocation: overflow control part.
+          *
+          * Unlike the theoritical scaled_curve_apply_advanced_parameters, here
+          * it's real encoding and we need to make sure we don't go so far from
+          * what is our ideal scaled curve.
+          *-----------------------------------------------------------------------*/
+         /* Compute the overflow we should compensate */
+         if (s->type != XVID_TYPE_IVOP || rc->overflow > 0) {
+                 double frametype_factor;
+                 double framesize_factor;
-         /* XXX: warning */
+                 /* Take only the desired part of overflow */
-         curve_temp = 0;
+                 overflow = rc->overflow;
-         if ((rc->param.curve_compression_high + rc->param.curve_compression_low) &&     s->type != XVID_TYPE_IVOP) {
+                 /* Factor that will take care to decrease the overflow applied
+                  * according to the importance of this frame type in term of
+                  * overall size */
+                 frametype_factor  = rc->count[XVID_TYPE_IVOP-1]*rc->avg_length[XVID_TYPE_IVOP-1];
+                 frametype_factor += rc->count[XVID_TYPE_PVOP-1]*rc->avg_length[XVID_TYPE_PVOP-1];
+                 frametype_factor += rc->count[XVID_TYPE_BVOP-1]*rc->avg_length[XVID_TYPE_BVOP-1];
+                 frametype_factor /= rc->count[s->type-1]*rc->avg_length[s->type-1];
+                 frametype_factor  = 1/frametype_factor;
+                 /* Factor that will take care not to compensate too much for this frame
+                  * size */
+                 framesize_factor  = dbytes;
+                 framesize_factor /= rc->avg_length[s->type-1];
-                 curve_temp = rc->curve_comp_scale;
+                 /* Treat only the overflow part concerned by this frame type and size */
-                 if (dbytes > rc->avg_length[s->type-1]) {
+                 overflow *= frametype_factor;
-                         curve_temp *= ((double)dbytes + (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_high / 100.0);
+ #if 0
-                 } else {
+                 /* Leave this one alone, as it impacts badly on quality */
-                         curve_temp *= ((double)dbytes + (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_low / 100.0);
+                 overflow *= framesize_factor;
-                 }
+ #endif
-                 desired += (int)curve_temp;
+                 /* Apply the overflow strength imposed by the user */
-                 rc->curve_comp_error += curve_temp - (int)curve_temp;
+                 overflow *= (rc->param.overflow_control_strength/100.0f);
          } else {
-                 desired += (int)dbytes;
+                 /* no negative overflow applied in IFrames because:
-                 rc->curve_comp_error += dbytes - (int)dbytes;
+                  *  - their role is important as they're references for P/BFrames.
+                  *  - there aren't much in typical sequences, so if an IFrame overflows too
+                  *    much, this overflow may impact the next IFrame too much and generate
+                  *    a sequence of poor quality frames */
+                 overflow = 0;
          }
+         /* Make sure we are not trying to compensate more overflow than we even have */
+         if (fabs(overflow) > fabs(rc->overflow))
+                 overflow = rc->overflow;
-         /*
+         /* Make sure the overflow doesn't make the frame size to get out of the range
-          * We can't do bigger frames than first pass, this would be stupid as first
+          * [-max_degradation..+max_improvment] */
-          * pass is quant=2 and that reaching quant=1 is not worth it. We would lose
+         if (overflow > dbytes*rc->param.max_overflow_improvement / 100) {
-          * many bytes and we would not not gain much quality.
+                 if(overflow <= dbytes)
-          */
+                         dbytes += dbytes * rc->param.max_overflow_improvement / 100;
-         if (desired > s->length) {
+                 else
-                 rc->curve_comp_error += desired - s->length;
+                         dbytes += overflow * rc->param.max_overflow_improvement / 100;
-                 desired = s->length;
+         } else if (overflow < - dbytes * rc->param.max_overflow_degradation / 100) {
+                 dbytes -= dbytes * rc->param.max_overflow_degradation / 100;
          } else {
-                 if (desired < rc->min_length[s->type-1]) {
+                 dbytes += overflow;
-                         if (s->type == XVID_TYPE_IVOP){
-                                 rc->curve_comp_error -= rc->min_length[XVID_TYPE_IVOP-1] - desired;
-                         }
-                         desired = rc->min_length[s->type-1];
                  }
-         }
-         s->desired_length = desired;
-         /*
-          * if this keyframe is too close to the next, reduce it's byte allotment
-          * XXX: why do we do this after setting the desired length ?
-          */
-         if (s->type == XVID_TYPE_IVOP) {
-                 int KFdistance = rc->keyframe_locations[rc->KF_idx] - rc->keyframe_locations[rc->KF_idx - 1];
-                 if (KFdistance < rc->param.kftreshold) {
+         /*-------------------------------------------------------------------------
+          * Frame bit allocation last part:
-                         KFdistance -= rc->param.min_key_interval;
+          *
+          * Cap frame length so we don't reach neither bigger frame sizes than first
-                         if (KFdistance >= 0) {
+          * pass nor smaller than the allowed minimum.
-                                 int KF_min_size;
+          *-----------------------------------------------------------------------*/
-                                 KF_min_size = desired * (100 - rc->param.kfreduction) / 100;
+ #ifdef PASS_SMALLER
-                                 if (KF_min_size < 1)
+         if (dbytes > s->length) {
-                                         KF_min_size = 1;
+                 dbytes = s->length;
-                                 desired = KF_min_size + (desired - KF_min_size) * KFdistance /
-                                         (rc->param.kftreshold - rc->param.min_key_interval);
-                                 if (desired < 1)
-                                         desired = 1;
-                         }
                  }
+ #endif
+         /* Prevent stupid desired sizes under logical values */
+         if (dbytes < rc->min_length[s->type-1]) {
+                 dbytes = rc->min_length[s->type-1];
          }
-         /*
+         /*------------------------------------------------------------------------
-          * The "sens commun" would force us to use rc->avg_length[s->type-1] but
+          * Desired frame length <-> quantizer mapping
-          * even VFW code uses the pframe average length. Note that this length is
+          *-----------------------------------------------------------------------*/
-          * used with desired which represents bframes _and_ pframes length.
-          *
-          * XXX: why are we using the avg pframe length for all frame types ?
-          */
-         overflow = (int)((double)overflow * desired / rc->avg_length[XVID_TYPE_PVOP-1]);
-         /* Reign in overflow with huge frames */
+ #ifdef BQUANT_PRESCALE
-         if (labs(overflow) > labs(rc->overflow))
+         /* For bframes we prescale the quantizer to avoid too high quant scaling */
-                 overflow = rc->overflow;
+         if(s->type == XVID_TYPE_BVOP) {
-         /* Make sure overflow doesn't run away */
+                 twopass_stat_t *b_ref = s;
-         if (overflow > desired * rc->param.max_overflow_improvement / 100) {
-                 desired += (overflow <= desired) ? desired * rc->param.max_overflow_improvement / 100 :
-                         overflow * rc->param.max_overflow_improvement / 100;
-         } else if (overflow < desired * rc->param.max_overflow_degradation / -100){
-                 desired += desired * rc->param.max_overflow_degradation / -100;
-         } else {
-                 desired += overflow;
-         }
-         /* Make sure we are not higher than desired frame size */
+                 /* Find the reference frame */
-         if (desired > rc->max_length) {
+                 while(b_ref != &rc->stats[0] && b_ref->type == XVID_TYPE_BVOP)
-                 capped_to_max_framesize = 1;
+                         b_ref--;
-                 desired = rc->max_length;
-                 DPRINTF(XVID_DEBUG_RC,"[%i] Capped to maximum frame size\n",
-                                 data->frame_num);
-         }
-         /* Make sure to not scale below the minimum framesize */
+                 /* Compute the original quant */
-         if (desired < rc->min_length[s->type-1]) {
+                 s->quant  = 2*(100*s->quant - data->bquant_offset);
-                 desired = rc->min_length[s->type-1];
+                 s->quant += data->bquant_ratio - 1; /* to avoid rounding issues */
-                 DPRINTF(XVID_DEBUG_RC,"[%i] Capped to minimum frame size\n",
+                 s->quant  = s->quant/data->bquant_ratio - b_ref->quant;
-                                 data->frame_num);
          }
+ #endif
-         /*
+         /* Don't laugh at this very 'simple' quant<->size relationship, it
-          * Don't laugh at this very 'simple' quant<->filesize relationship, it
+          * proves to be acurate enough for our algorithm */
-          * proves to be acurate enough for our algorithm
+         scaled_quant = (double)s->quant*(double)s->length/(double)dbytes;
-          */
-         scaled_quant = (double)s->quant*(double)s->length/(double)desired;
+ #ifdef COMPENSATE_FORMULA
+         /* We know xvidcore will apply the bframe formula again, so we compensate
+          * it right now to make sure we would not apply it twice */
+         if(s->type == XVID_TYPE_BVOP) {
+                 twopass_stat_t *b_ref = s;
+                 /* Find the reference frame */
+                 while(b_ref != &rc->stats[0] && b_ref->type == XVID_TYPE_BVOP)
+                         b_ref--;
+                 /* Compute the quant it would be if the core did not apply the bframe
+                  * formula */
+                 scaled_quant  = 100*scaled_quant - data->bquant_offset;
+                 scaled_quant += data->bquant_ratio - 1; /* to avoid rouding issues */
+                 scaled_quant /= data->bquant_ratio;
+         }
+ #endif
-         /*
+         /* Quantizer has been scaled using floating point operations/results, we
-          * Quantizer has been scaled using floating point operations/results, we
+          * must cast it to integer */
-          * must cast it to integer
-          */
          data->quant = (int)scaled_quant;
          /* Let's clip the computed quantizer, if needed */
-Line 516
+Line 741
                  data->quant = 1;
          } else if (data->quant > 31) {
                  data->quant = 31;
-         } else if (s->type != XVID_TYPE_IVOP) {
+         } else {
-                 /*
+                 /* The frame quantizer has not been clipped, this appears to be a good
-                  * The frame quantizer has not been clipped, this appears to be a good
                   * computed quantizer, do not loose quantizer decimal part that we
-                  * accumulate for later reuse when its sum represents a complete unit.
+                  * accumulate for later reuse when its sum represents a complete
-                  */
+                  * unit. */
                  rc->quant_error[s->type-1][data->quant] += scaled_quant - (double)data->quant;
                  if (rc->quant_error[s->type-1][data->quant] >= 1.0) {
-Line 532
+Line 756
                          rc->quant_error[s->type-1][data->quant] += 1.0;
                          data->quant--;
                  }
          }
-         /*
+         /* Now we have a computed quant that is in the right quante range, with a
-          * Now we have a computed quant that is in the right quante range, with a
           * possible +1 correction due to cumulated error. We can now safely clip
           * the quantizer again with user's quant ranges. "Safely" means the Rate
           * Control could learn more about this quantizer, this knowledge is useful
           * for future frames even if it this quantizer won't be really used atm,
-          * that's why we don't perform this clipping earlier.
+          * that's why we don't perform this clipping earlier. */
-          */
          if (data->quant < data->min_quant[s->type-1]) {
                  data->quant = data->min_quant[s->type-1];
          } else if (data->quant > data->max_quant[s->type-1]) {
                  data->quant = data->max_quant[s->type-1];
          }
-         /*
+         if (data->quant < rc->min_quant) data->quant = rc->min_quant;
-          * To avoid big quality jumps from frame to frame, we apply a "security"
+         /* To avoid big quality jumps from frame to frame, we apply a "security"
           * rule that makes |last_quant - new_quant| <= 2. This rule only applies
-          * to predicted frames (P and B)
+          * to predicted frames (P and B) */
-          */
          if (s->type != XVID_TYPE_IVOP && rc->last_quant[s->type-1] && capped_to_max_framesize == 0) {
                  if (data->quant > rc->last_quant[s->type-1] + 2) {
                          data->quant = rc->last_quant[s->type-1] + 2;
                          DPRINTF(XVID_DEBUG_RC,
-                                         "[%i] p/b-frame quantizer prevented from rising too steeply\n",
+                                         "[xvid rc] -- frame %d p/b-frame quantizer prevented from rising too steeply\n",
                                          data->frame_num);
                  }
                  if (data->quant < rc->last_quant[s->type-1] - 2) {
                          data->quant = rc->last_quant[s->type-1] - 2;
                          DPRINTF(XVID_DEBUG_RC,
-                                         "[%i] p/b-frame quantizer prevented from falling too steeply\n",
+                                         "[xvid rc] -- frame:%d p/b-frame quantizer prevented from falling too steeply\n",
                                          data->frame_num);
                  }
          }
-         /*
+         /* We don't want to pollute the RC histerisis when our computed quant has
-          * We don't want to pollute the RC history results when our computed quant
+          * been computed from a capped frame size */
-          * has been computed from a capped frame size
-          */
          if (capped_to_max_framesize == 0)
                  rc->last_quant[s->type-1] = data->quant;
-         /* Force frame type */
+         /* Don't forget to force 1st pass frame type ;-) */
+         if (rc->scaled_frames)
          data->type = s->type;
+         rc->scaled_frames++;
          return 0;
  }
-Line 590
+Line 811
  rc_2pass2_after(rc_2pass2_t * rc, xvid_plg_data_t * data)
  {
          const char frame_type[4] = { 'i', 'p', 'b', 's'};
-         stat_t * s = &rc->stats[data->frame_num];
+         twopass_stat_t * s = &rc->stats[data->frame_num];
          /* Insufficent stats data */
      if (data->frame_num >= rc->num_frames)
          return 0;
-     rc->quant_count[data->quant]++;
+         /* Update the quantizer counter */
+         rc->quant_count[s->type-1][data->quant]++;
+         /* Update the frame type overflow */
      if (data->type == XVID_TYPE_IVOP) {
-         int kfdiff = (rc->keyframe_locations[rc->KF_idx] -      rc->keyframe_locations[rc->KF_idx - 1]);
+                 int kfdiff = 0;
+                 if(rc->KF_idx != rc->num_frames -1) {
+                         kfdiff  = rc->keyframe_locations[rc->KF_idx+1];
+                         kfdiff -= rc->keyframe_locations[rc->KF_idx];
+                 }
+                 /* Flush Keyframe overflow accumulator */
          rc->overflow += rc->KFoverflow;
+                 /* Store the frame overflow to the keyframe accumulator */
          rc->KFoverflow = s->desired_length - data->length;
-         if (kfdiff > 1) {  /* non-consecutive keyframes */
+                 if (kfdiff > 1) {
+                         /* Non-consecutive keyframes case:
+                          * We can then divide this total keyframe overflow into equal parts
+                          * that we will distribute into regular overflow at each frame
+                          * between the sequence bounded by two IFrames */
              rc->KFoverflow_partial = rc->KFoverflow / (kfdiff - 1);
-         }else{ /* consecutive keyframes */
+                 } else {
+                         /* Consecutive keyframes case:
+                          * Flush immediatly the keyframe overflow and reset keyframe
+                          * overflow */
                          rc->overflow += rc->KFoverflow;
                          rc->KFoverflow = 0;
                          rc->KFoverflow_partial = 0;
          }
          rc->KF_idx++;
      } else {
-         /* distribute part of the keyframe overflow */
+                 /* Accumulate the frame overflow */
-         rc->overflow += s->desired_length - data->length + rc->KFoverflow_partial;
+                 rc->overflow += s->desired_length - data->length;
+                 /* Distribute part of the keyframe overflow */
+                 rc->overflow += rc->KFoverflow_partial;
+                 /* Don't forget to substract that same amount from the total keyframe
+                  * overflow */
          rc->KFoverflow -= rc->KFoverflow_partial;
      }
-         DPRINTF(XVID_DEBUG_RC, "[%i] type:%c quant:%i stats1:%i scaled:%i actual:%i desired:%d overflow:%i\n",
+         s->error = s->desired_length - data->length;
+         rc->real_total += data->length;
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- frame:%d type:%c quant:%d stats:%d scaled:%d desired:%d actual:%d error:%d overflow:%.2f\n",
                          data->frame_num,
                          frame_type[data->type-1],
                          data->quant,
                          s->length,
                          s->scaled_length,
-                         data->length,
                          s->desired_length,
+                         s->desired_length - s->error,
+                         -s->error,
                          rc->overflow);
      return(0);
-Line 635
+Line 883
   * Helper functions definition
   ****************************************************************************/
+ /* Default buffer size for reading lines */
  #define BUF_SZ   1024
- #define MAX_COLS 5
- /* open stats file, and count num frames */
+ /* Helper functions for reading/parsing the stats file */
+ static char *skipspaces(char *string);
+ static int iscomment(char *string);
+ static char *readline(FILE *f);
+ /* This function counts the number of frame entries in the stats file
+  * It also counts the number of I Frames */
  static int
- det_stats_length(rc_2pass2_t * rc, char * filename)
+ statsfile_count_frames(rc_2pass2_t * rc, char * filename)
  {
      FILE * f;
-     int n, ignore;
+         char *line;
-     char type;
+         int lines;
      rc->num_frames = 0;
      rc->num_keyframes = 0;
-     if ((f = fopen(filename, "rt")) == NULL)
+         if ((f = fopen(filename, "rb")) == NULL)
-         return 0;
+                 return(-1);
-     while((n = fscanf(f, "%c %d %d %d %d %d %d\n",
+         lines = 0;
-         &type, &ignore, &ignore, &ignore, &ignore, &ignore, &ignore)) != EOF) {
+         while ((line = readline(f)) != NULL) {
-         if (type == 'i') {
-             rc->num_frames++;
+                 char *ptr;
+                 char type;
+                 int fields;
+                 lines++;
+                 /* We skip spaces */
+                 ptr = skipspaces(line);
+                 /* Skip coment lines or empty lines */
+                 if(iscomment(ptr) || *ptr == '\0') {
+                         free(line);
+                         continue;
+                 }
+                 /* Read the stat line from buffer */
+                 fields = sscanf(ptr, "%c", &type);
+                 /* Valid stats files have at least 7 fields */
+                 if (fields == 1) {
+                         switch(type) {
+                         case 'i':
+                         case 'I':
              rc->num_keyframes++;
-         }else if (type == 'p' || type == 'b' || type == 's') {
+                         case 'p':
+                         case 'P':
+                         case 'b':
+                         case 'B':
+                         case 's':
+                         case 'S':
              rc->num_frames++;
+                                 break;
+                         default:
+                                 DPRINTF(XVID_DEBUG_RC,
+                                                 "[xvid rc] -- WARNING: L%d unknown frame type used (%c).\n",
+                                                 lines, type);
+                         }
+                 } else {
+                                 DPRINTF(XVID_DEBUG_RC,
+                                                 "[xvid rc] -- WARNING: L%d misses some stat fields (%d).\n",
+                                                 lines, 7-fields);
          }
+                 /* Free the line buffer */
+                 free(line);
      }
+         /* We are done with the file */
      fclose(f);
-     return 1;
+         if (!rc->num_keyframes) return (-1); /* No keyframes? Then something is wrong */
+         else return(0);
  }
  /* open stats file(s) and read into rc->stats array */
  static int
- load_stats(rc_2pass2_t *rc, char * filename)
+ statsfile_load(rc_2pass2_t *rc, char * filename)
  {
      FILE * f;
-     int i, not_scaled;
+         int processed_entries;
-     if ((f = fopen(filename, "rt"))==NULL)
+         /* Opens the file */
-         return 0;
+         if ((f = fopen(filename, "rb"))==NULL)
+                 return(-1);
-     i = 0;
+         processed_entries = 0;
-         not_scaled = 0;
+         while(processed_entries < rc->num_frames) {
-     while(i < rc->num_frames) {
-         stat_t * s = &rc->stats[i];
-         int n;
          char type;
+                 int fields;
+                 twopass_stat_t * s = &rc->stats[processed_entries];
+                 char *line, *ptr;
+                 /* Read the line from the file */
+                 if((line = readline(f)) == NULL)
+                         break;
+                 /* We skip spaces */
+                 ptr = skipspaces(line);
+                 /* Skip comment lines or empty lines */
+                 if(iscomment(ptr) || *ptr == '\0') {
+                         free(line);
+                         continue;
+                 }
+                 /* Reset this field that is optional */
                  s->scaled_length = 0;
-         n = fscanf(f, "%c %d %d %d %d %d %d\n", &type, &s->quant, &s->blks[0], &s->blks[1], &s->blks[2], &s->length, &s->scaled_length);
-         if (n == EOF) break;
-                 if (n < 7) {
-                         not_scaled = 1;
-                 }
-         if (type == 'i') {
+                 /* Convert the fields */
+                 fields = sscanf(ptr,
+                                                 "%c %d %d %d %d %d %d %d\n",
+                                                 &type,
+                                                 &s->quant,
+                                                 &s->blks[0], &s->blks[1], &s->blks[2],
+                                                 &s->length, &s->invariant /* not really yet */,
+                                                 &s->scaled_length);
+                 /* Free line buffer, we don't need it anymore */
+                 free(line);
+                 /* Fail silently, this has probably been warned in
+                  * statsfile_count_frames */
+                 if(fields != 7 && fields != 8)
+                         continue;
+                 /* Convert frame type and compute the invariant length part */
+                 switch(type) {
+                 case 'i':
+                 case 'I':
              s->type = XVID_TYPE_IVOP;
-         }else if (type == 'p' || type == 's') {
+                         s->invariant /= INVARIANT_HEADER_PART_IVOP;
+                         break;
+                 case 'p':
+                 case 'P':
+                 case 's':
+                 case 'S':
              s->type = XVID_TYPE_PVOP;
-         }else if (type == 'b') {
+                         s->invariant /= INVARIANT_HEADER_PART_PVOP;
+                         break;
+                 case 'b':
+                 case 'B':
              s->type = XVID_TYPE_BVOP;
-         }else{  /* unknown type */
+                         s->invariant /= INVARIANT_HEADER_PART_BVOP;
-             DPRINTF(XVID_DEBUG_RC, "WARNING: unknown stats frame type, assuming pvop\n");
+                         break;
-             s->type = XVID_TYPE_PVOP;
+                 default:
+                         /* Same as before, fail silently */
+                         continue;
          }
-         i++;
+                 /* Ok it seems it's been processed correctly */
+                 processed_entries++;
      }
-     rc->num_frames = i;
+         /* Close the file */
          fclose(f);
-     return 1;
+         return(0);
- }
- #if 0
- static void print_stats(rc_2pass2_t * rc)
- {
-     int i;
-     DPRINTF(XVID_DEBUG_RC, "type quant length scaled_length\n");
-         for (i = 0; i < rc->num_frames; i++) {
-         stat_t * s = &rc->stats[i];
-         DPRINTF(XVID_DEBUG_RC, "%d %d %d %d\n", s->type, s->quant, s->length, s->scaled_length);
-     }
  }
- #endif
  /* pre-process the statistics data
-     - for each type, count, tot_length, min_length, max_length
+  * - for each type, count, tot_length, min_length, max_length
-     - set keyframes_locations
+  * - set keyframes_locations, tot_prescaled */
- */
  static void
- pre_process0(rc_2pass2_t * rc)
+ first_pass_stats_prepare_data(rc_2pass2_t * rc)
  {
      int i,j;
-         /*
+         /* *rc fields initialization
-          * *rc fields initialization
           * NB: INT_MAX and INT_MIN are used in order to be immediately replaced
-          *     with real values of the 1pass
+          *     with real values of the 1pass */
-          */
           for (i=0; i<3; i++) {
                  rc->count[i]=0;
                  rc->tot_length[i] = 0;
+                 rc->tot_invariant[i] = 0;
                  rc->min_length[i] = INT_MAX;
      }
          rc->max_length = INT_MIN;
+         rc->tot_weighted = 0;
-         /*
+         /* Loop through all frames and find/compute all the stuff this function
-          * Loop through all frames and find/compute all the stuff this function
+          * is supposed to do */
-          * is supposed to do
-          */
          for (i=j=0; i<rc->num_frames; i++) {
-                 stat_t * s = &rc->stats[i];
+                 twopass_stat_t * s = &rc->stats[i];
                  rc->count[s->type-1]++;
                  rc->tot_length[s->type-1] += s->length;
+                 rc->tot_invariant[s->type-1] += s->invariant;
+                 if (s->zone_mode != XVID_ZONE_QUANT)
+                         rc->tot_weighted += (int)(s->weight*(s->length - s->invariant));
                  if (s->length < rc->min_length[s->type-1]) {
                          rc->min_length[s->type-1] = s->length;
-Line 773
+Line 1094
                  }
          }
-         /*
+         /* NB:
-          * Nota Bene:
           * The "per sequence" overflow system considers a natural sequence to be
           * formed by all frames between two iframes, so if we want to make sure
           * the system does not go nuts during last sequence, we force the last
-          * frame to appear in the keyframe locations array.
+          * frame to appear in the keyframe locations array. */
-          */
      rc->keyframe_locations[j] = i;
-         DPRINTF(XVID_DEBUG_RC, "Min 1st pass IFrame length: %d\n", rc->min_length[0]);
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Min 1st pass IFrame length: %d\n", rc->min_length[0]);
-         DPRINTF(XVID_DEBUG_RC, "Min 1st pass PFrame length: %d\n", rc->min_length[1]);
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Min 1st pass PFrame length: %d\n", rc->min_length[1]);
-         DPRINTF(XVID_DEBUG_RC, "Min 1st pass BFrame length: %d\n", rc->min_length[2]);
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Min 1st pass BFrame length: %d\n", rc->min_length[2]);
  }
  /* calculate zone weight "center" */
  static void
  zone_process(rc_2pass2_t *rc, const xvid_plg_create_t * create)
  {
      int i,j;
      int n = 0;
-     rc->avg_weight = 0.0;
      rc->tot_quant = 0;
+         rc->tot_quant_invariant = 0;
      if (create->num_zones == 0) {
          for (j = 0; j < rc->num_frames; j++) {
              rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
              rc->stats[j].weight = 1.0;
          }
-         rc->avg_weight += rc->num_frames * 1.0;
          n += rc->num_frames;
      }
-Line 813
+Line 1129
          int next = (i+1<create->num_zones) ? create->zones[i+1].frame : rc->num_frames;
+                 /* Zero weight make no sense */
+                 if (create->zones[i].increment == 0) create->zones[i].increment = 1;
+                 /* And obviously an undetermined infinite makes even less sense */
+                 if (create->zones[i].base == 0) create->zones[i].base = 1;
          if (i==0 && create->zones[i].frame > 0) {
              for (j = 0; j < create->zones[i].frame && j < rc->num_frames; j++) {
                  rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
                  rc->stats[j].weight = 1.0;
              }
-             rc->avg_weight += create->zones[i].frame * 1.0;
              n += create->zones[i].frame;
          }
-Line 828
+Line 1148
                  rc->stats[j].weight = (double)create->zones[i].increment / (double)create->zones[i].base;
              }
              next -= create->zones[i].frame;
-             rc->avg_weight += (double)(next * create->zones[i].increment) / (double)create->zones[i].base;
              n += next;
          }else{  /* XVID_ZONE_QUANT */
              for (j = create->zones[i].frame; j < next && j < rc->num_frames; j++ ) {
                  rc->stats[j].zone_mode = XVID_ZONE_QUANT;
                  rc->stats[j].weight = (double)create->zones[i].increment / (double)create->zones[i].base;
                  rc->tot_quant += rc->stats[j].length;
+                                 rc->tot_quant_invariant += rc->stats[j].invariant;
              }
          }
      }
-     rc->avg_weight = n>0 ? rc->avg_weight/n : 1.0;
-     DPRINTF(XVID_DEBUG_RC, "center_weight: %f (for %i frames);   fixed_bytes: %i\n", rc->avg_weight, n, rc->tot_quant);
  }
  /* scale the curve */
  static void
- internal_scale(rc_2pass2_t *rc)
+ first_pass_scale_curve_internal(rc_2pass2_t *rc)
  {
-         int64_t target  = rc->target - rc->tot_quant;
+         int64_t target;
-         int64_t pass1_length = rc->tot_length[0] + rc->tot_length[1] + rc->tot_length[2] - rc->tot_quant;
+         int64_t total_invariant;
          double scaler;
          int i, num_MBs;
+         /* We only scale texture data ! */
+         total_invariant  = rc->tot_invariant[XVID_TYPE_IVOP-1];
+         total_invariant += rc->tot_invariant[XVID_TYPE_PVOP-1];
+         total_invariant += rc->tot_invariant[XVID_TYPE_BVOP-1];
+         /* don't forget to substract header bytes used in quant zones, otherwise we
+          * counting them twice */
+         total_invariant -= rc->tot_quant_invariant;
+         /* We remove the bytes used by the fixed quantizer zones during first pass
+          * with the same quants, so we know very precisely how much that
+          * represents */
+         target  = rc->target;
+         target -= rc->tot_quant;
          /* Let's compute a linear scaler in order to perform curve scaling */
-         scaler = (double)target / (double)pass1_length;
+         scaler = (double)(target - total_invariant) / (double)(rc->tot_weighted);
-         if (target <= 0 || pass1_length <= 0 || target >= pass1_length) {
+ #ifdef SMART_OVERFLOW_SETTING
-                 DPRINTF(XVID_DEBUG_RC, "WARNING: Undersize detected\n");
+         if (scaler > 0.9) {
-         scaler = 1.0;
+                 rc->param.max_overflow_degradation *= 5;
+                 rc->param.max_overflow_improvement *= 5;
+                 rc->param.overflow_control_strength *= 3;
+         } else if (scaler > 0.6) {
+                 rc->param.max_overflow_degradation *= 2;
+                 rc->param.max_overflow_improvement *= 2;
+                 rc->param.overflow_control_strength *= 2;
+         } else {
+                 rc->min_quant = 2;
          }
+ #endif
-     DPRINTF(XVID_DEBUG_RC,
+         /* Compute min frame lengths (for each frame type) according to the number
-                         "Before correction: target=%i, tot_length=%i, scaler=%f\n",
+          * of MBs. We sum all block type counters of frame 0, this gives us the
-                         (int)target, (int)pass1_length, scaler);
+          * number of MBs.
-         /*
-          * Compute min frame lengths (for each frame type) according to the number
-          * of MBs. We sum all blocks count from frame 0 (should be an IFrame, so
-          * blocks[0] should be enough) to know how many MBs there are.
           *
           * We compare these hardcoded values with observed values in first pass
-          * (determined in pre_process0).Then we keep the real minimum.
+          * (determined in pre_process0).Then we keep the real minimum. */
-          */
-         num_MBs = rc->stats[0].blks[0] + rc->stats[0].blks[1] + rc->stats[0].blks[2];
-         if(rc->min_length[0] > ((num_MBs*22) + 240) / 8)
+         /* Number of MBs */
-                 rc->min_length[0] = ((num_MBs*22) + 240) / 8;
+         num_MBs  = rc->stats[0].blks[0];
+         num_MBs += rc->stats[0].blks[1];
+         num_MBs += rc->stats[0].blks[2];
+         /* Minimum for I frames */
+         if(rc->min_length[XVID_TYPE_IVOP-1] > ((num_MBs*22) + 240) / 8)
+                 rc->min_length[XVID_TYPE_IVOP-1] = ((num_MBs*22) + 240) / 8;
+         /* Minimum for P/S frames */
+         if(rc->min_length[XVID_TYPE_PVOP-1] > ((num_MBs) + 88)  / 8)
+                 rc->min_length[XVID_TYPE_PVOP-1] = ((num_MBs) + 88)  / 8;
+         /* Minimum for B frames */
+         if(rc->min_length[XVID_TYPE_BVOP-1] > 8)
+                 rc->min_length[XVID_TYPE_BVOP-1] = 8;
-         if(rc->min_length[1] > ((num_MBs) + 88)  / 8)
+         /* Perform an initial scale pass.
-                 rc->min_length[1] = ((num_MBs) + 88)  / 8;
+          *
-         if(rc->min_length[2] > 8)
-                 rc->min_length[2] = 8;
-         /*
-          * Perform an initial scale pass.
           * If a frame size is scaled underneath our hardcoded minimums, then we
           * force the frame size to the minimum, and deduct the original & scaled
-          * frame length from the original and target total lengths
+          * frame length from the original and target total lengths */
-          */
          for (i=0; i<rc->num_frames; i++) {
-                 stat_t * s = &rc->stats[i];
+                 twopass_stat_t * s = &rc->stats[i];
                  int len;
+                 /* No need to scale frame length for which a specific quantizer is
+                  * specified thanks to zones */
          if (s->zone_mode == XVID_ZONE_QUANT) {
              s->scaled_length = s->length;
                          continue;
                  }
-                 /* Compute the scaled length */
+                 /* Compute the scaled length -- only non invariant data length is scaled */
-                 len = (int)((double)s->length * scaler * s->weight / rc->avg_weight);
+                 len = s->invariant + (int)((double)(s->length-s->invariant) * scaler * s->weight);
                  /* Compare with the computed minimum */
                  if (len < rc->min_length[s->type-1]) {
-                         /* force frame size to our computed minimum */
+                         /* This is a 'forced size' frame, set its frame size to the
+                          * computed minimum */
                          s->scaled_length = rc->min_length[s->type-1];
+                         /* Remove both scaled and original size from their respective
+                          * total counters, as we prepare a second pass for 'regular'
+                          * frames */
                          target -= s->scaled_length;
-                         pass1_length -= s->length;
                  } else {
                          /* Do nothing for now, we'll scale this later */
                          s->scaled_length = 0;
                  }
          }
-         /* Correct the scaler for all non forced frames */
+         /* The first pass on data substracted all 'forced size' frames from the
-         scaler = (double)target / (double)pass1_length;
+          * total counters. Now, it's possible to scale the 'regular' frames. */
-         /* Detect undersizing */
+         /* Scaling factor for 'regular' frames */
-     if (target <= 0 || pass1_length <= 0 || target >= pass1_length) {
+         scaler = (double)(target - total_invariant) / (double)(rc->tot_weighted);
-                 DPRINTF(XVID_DEBUG_RC, "WARNING: Undersize detected\n");
-                 scaler = 1.0;
-         }
-         DPRINTF(XVID_DEBUG_RC,
-                         "After correction: target=%i, tot_length=%i, scaler=%f\n",
-                         (int)target, (int)pass1_length, scaler);
          /* Do another pass with the new scaler */
          for (i=0; i<rc->num_frames; i++) {
-                 stat_t * s = &rc->stats[i];
+                 twopass_stat_t * s = &rc->stats[i];
                  /* Ignore frame with forced frame sizes */
                  if (s->scaled_length == 0)
-                         s->scaled_length = (int)((double)s->length * scaler * s->weight / rc->avg_weight);
+                         s->scaled_length = s->invariant + (int)((double)(s->length-s->invariant) * scaler * s->weight);
          }
+         /* Job done */
+         return;
  }
+ /* Apply all user settings to the scaled curve
+  * This implies:
+  *   keyframe boosting
+  *   high/low compression */
  static void
- pre_process1(rc_2pass2_t * rc)
+ scaled_curve_apply_advanced_parameters(rc_2pass2_t * rc)
  {
      int i;
-     double total1, total2;
+         int64_t ivop_boost_total;
-     uint64_t ivop_boost_total;
-     ivop_boost_total = 0;
+         /* Reset the rate controller (per frame type) total byte counters */
-     rc->curve_comp_error = 0;
+         for (i=0; i<3; i++) rc->tot_scaled_length[i] = 0;
-     for (i=0; i<3; i++) {
+         /* Compute total bytes for each frame type */
-         rc->tot_scaled_length[i] = 0;
+         for (i=0; i<rc->num_frames;i++) {
+                 twopass_stat_t *s = &rc->stats[i];
+                 rc->tot_scaled_length[s->type-1] += s->scaled_length;
      }
+         /* First we compute the total amount of bits needed, as being described by
+          * the scaled distribution. During this pass over the complete stats data,
+          * we see how much bits two user settings will get/give from/to p&b frames:
+          *  - keyframe boosting
+          *  - keyframe distance penalty */
+         rc->KF_idx = 0;
+         ivop_boost_total = 0;
      for (i=0; i<rc->num_frames; i++) {
-         stat_t * s = &rc->stats[i];
+                 twopass_stat_t * s = &rc->stats[i];
-         rc->tot_scaled_length[s->type-1] += s->scaled_length;
+                 /* Some more work is needed for I frames */
          if (s->type == XVID_TYPE_IVOP) {
-             ivop_boost_total += s->scaled_length * rc->param.keyframe_boost / 100;
+                         int ivop_boost;
+                         /* Accumulate bytes needed for keyframe boosting */
+                         ivop_boost = s->scaled_length*rc->param.keyframe_boost/100;
+ #if 0 /* ToDo: decide how to apply kfthresholding */
+ #endif
+                         /* If the frame size drops under the minimum length, then cap ivop_boost */
+                         if (ivop_boost + s->scaled_length < rc->min_length[XVID_TYPE_IVOP-1])
+                                 ivop_boost = rc->min_length[XVID_TYPE_IVOP-1] - s->scaled_length;
+                         /* Accumulate the ivop boost */
+                         ivop_boost_total += ivop_boost;
+                         /* Don't forget to update the keyframe index */
+                         rc->KF_idx++;
          }
      }
-     rc->movie_curve = ((double)(rc->tot_scaled_length[XVID_TYPE_PVOP-1] + rc->tot_scaled_length[XVID_TYPE_BVOP-1] + ivop_boost_total) /
+         /* Initialize the IBoost tax ratio for P/S/B frames
-                                         (rc->tot_scaled_length[XVID_TYPE_PVOP-1] + rc->tot_scaled_length[XVID_TYPE_BVOP-1]));
+          *
+          * This ratio has to be applied to p/b/s frames in order to reserve
+          * additional bits for keyframes (keyframe boosting) or if too much
+          * keyframe distance is applied, bits retrieved from the keyframes.
+          *
+          * ie pb_length *= rc->pb_iboost_tax_ratio;
+          *
+          *    gives the ideal length of a p/b frame */
+         /* Compute the total length of p/b/s frames (temporary storage into
+          * movie_curve) */
+         rc->pb_iboost_tax_ratio  = (double)rc->tot_scaled_length[XVID_TYPE_PVOP-1];
+         rc->pb_iboost_tax_ratio += (double)rc->tot_scaled_length[XVID_TYPE_BVOP-1];
+         /* Compute the ratio described above
+          *     taxed_total = sum(0, n, tax*scaled_length)
+          * <=> taxed_total = tax.sum(0, n, scaled_length)
+          * <=> tax = taxed_total / original_total */
+         rc->pb_iboost_tax_ratio =
+                 (rc->pb_iboost_tax_ratio - ivop_boost_total) /
+                 rc->pb_iboost_tax_ratio;
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- IFrame boost tax ratio:%.2f\n",
+                         rc->pb_iboost_tax_ratio);
+         /* Compute the average size of frames per frame type */
      for(i=0; i<3; i++) {
-         if (rc->count[i] == 0 || rc->movie_curve == 0) {
+                 /* Special case for missing type or weird case */
+                 if (rc->count[i] == 0 || rc->pb_iboost_tax_ratio == 0) {
              rc->avg_length[i] = 1;
          }else{
-             rc->avg_length[i] = rc->tot_scaled_length[i] / rc->count[i] / rc->movie_curve;
+                         rc->avg_length[i] = (double)rc->tot_scaled_length[i];
+                         if (i == (XVID_TYPE_IVOP-1)) {
+                                 /* I Frames total has to be added the boost total */
+                                 rc->avg_length[i] += ivop_boost_total;
+                         } else {
+                                 /* P/B frames has to taxed */
+                                 rc->avg_length[i] *= rc->pb_iboost_tax_ratio;
+                         }
+                         /* Finally compute the average frame size */
+                         rc->avg_length[i] /= (double)rc->count[i];
+                 }
+         }
+         /* Assymetric curve compression */
+         if (rc->param.curve_compression_high || rc->param.curve_compression_low) {
+                 double symetric_total;
+                 double assymetric_delta_total;
+                 /* Like I frame boosting, assymetric curve compression modifies the total
+                  * amount of needed bits, we must compute the ratio so we can prescale
+                  lengths */
+                 symetric_total = 0;
+                 assymetric_delta_total = 0;
+                 for (i=0; i<rc->num_frames; i++) {
+                         double assymetric_delta;
+                         double dbytes;
+                         twopass_stat_t * s = &rc->stats[i];
+                         /* I Frames are not concerned by assymetric scaling */
+                         if (s->type == XVID_TYPE_IVOP)
+                                 continue;
+                         /* During the real run, we would have to apply the iboost tax */
+                         dbytes = s->scaled_length * rc->pb_iboost_tax_ratio;
+                         /* Update the symmetric curve compression total */
+                         symetric_total += dbytes;
+                         /* Apply assymetric curve compression */
+                         if (dbytes > rc->avg_length[s->type-1])
+                                 assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * (double)rc->param.curve_compression_high / 100.0f;
+                         else
+                                 assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * (double)rc->param.curve_compression_low  / 100.0f;
+                         /* Cap to the minimum frame size if needed */
+                         if (dbytes + assymetric_delta < rc->min_length[s->type-1])
+                                 assymetric_delta = rc->min_length[s->type-1] - dbytes;
+                         /* Accumulate after assymetric curve compression */
+                         assymetric_delta_total += assymetric_delta;
+                 }
+                 /* Compute the tax that all p/b frames have to pay in order to respect the
+                  * bit distribution changes that the assymetric compression curve imposes
+                  * We want assymetric_total = sum(0, n-1, tax.scaled_length)
+                  *      ie assymetric_total = ratio.sum(0, n-1, scaled_length)
+                  *         ratio = assymetric_total / symmetric_total */
+                 rc->assymetric_tax_ratio = ((double)symetric_total - (double)assymetric_delta_total) / (double)symetric_total;
+         } else {
+                 rc->assymetric_tax_ratio = 1.0f;
          }
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Assymetric tax ratio:%.2f\n", rc->assymetric_tax_ratio);
+         /* Last bits that need to be reset */
+         rc->overflow = 0;
+         rc->KFoverflow = 0;
+         rc->KFoverflow_partial = 0;
+         rc->KF_idx = 0;
+         rc->desired_total = 0;
+         rc->real_total = 0;
+         /* Job done */
+         return;
      }
-     /* --- */
+ /*****************************************************************************
+  * VBV compliancy check and scale
+  * MPEG-4 standard specifies certain restrictions for bitrate/framesize in VBR
+  * to enable playback on devices with limited readspeed and memory (and which
+  * aren't...)
+  *
+  * DivX profiles have 2 criteria: VBV as in MPEG standard
+  *                                a limit on peak bitrate for any 1 second
+  *
+  * But if VBV is fulfilled, peakrate is automatically fulfilled in any profile
+  * defined so far, so we check for it (for completeness) but correct only VBV
+  *
+  *****************************************************************************/
+ #define VBV_COMPLIANT 0
+ #define VBV_UNDERFLOW 1  /* video buffer runs empty */
+ #define VBV_OVERFLOW  2  /* doesn't exist for VBR encoding */
+ #define VBV_PEAKRATE  4  /* peak bitrate (within 1s) violated */
+ static int
+ check_curve_for_vbv_compliancy(rc_2pass2_t * rc, const float fps)
+ {
+         /* We do all calculations in float, for higher accuracy,
+          * and in bytes for convenience.
+          *
+          * typical values from e.g. Home profile:
+          *  vbv_size= 384*1024 (384kB)
+          *  vbv_initial= 288*1024 (75% fill)
+          *  maxrate= 4854000 (4.854MBps)
+          *  peakrate= 8000000 (8MBps)
+          *
+          *  PAL: offset1s = 25 (1 second of 25fps)
+          *  NTSC: offset1s = 30 (1 second of 29.97fps) or 24 (1 second of 23.976fps)
+          */
-     total1=total2=0;
+         const float vbv_size = (float)rc->param.vbv_size/8.f;
+         float vbvfill = (float)rc->param.vbv_initial/8.f;
+         float vbvmin;
+         const float maxrate = (float)rc->param.vbv_maxrate;
+         const float peakrate = (float)rc->param.vbv_peakrate;
+         const float r0 = (int)(maxrate/fps+0.5)/8.f;
+         int bytes1s = 0;
+         int offset1s = (int)(1.f*fps+0.5);
+         int i;
+         /* 1Gbit should be enough to inuitialize the vbvmin
+          *      an arbitrary high value */
+         vbvmin = 1000*1000*1000;
      for (i=0; i<rc->num_frames; i++) {
-         stat_t * s = &rc->stats[i];
+                 /* DivX 1s peak bitrate check  */
+                 bytes1s += rc->stats[i].scaled_length;
+                 if (i>=offset1s)
+                         bytes1s -= rc->stats[i-offset1s].scaled_length;
+     /* ignore peakrate constraint if peakrate is <= 0.f */
+                 if (peakrate>0.f && 8.f*bytes1s > peakrate)
+                         return(VBV_PEAKRATE);
+                 /* update vbv fill level */
+                 vbvfill += r0 - rc->stats[i].scaled_length;
+                 /* this check is _NOT_ an "overflow"! only reading from disk stops then */
+                 if (vbvfill > vbv_size)
+                         vbvfill = vbv_size;
+                 /* but THIS would be an underflow. report it! */
+                 if (vbvfill < 0)
+                         return(VBV_UNDERFLOW);
+                 /* Store the minimum buffer filling */
+                 if (vbvfill < vbvmin)
+                         vbvmin = vbvfill;
+         }
+         DPRINTF(XVID_DEBUG_RC, "[xvid rc] Minimum buffer fill: %f bytes\n", vbvmin);
-         if (s->type != XVID_TYPE_IVOP) {
+         return(VBV_COMPLIANT);
-             double dbytes,dbytes2;
+ }
-             dbytes = s->scaled_length / rc->movie_curve;
-             dbytes2 = 0; /* XXX: warning */
-             total1 += dbytes;
-                         if (dbytes > rc->avg_length[s->type-1]) {
+ static int
-                                 dbytes2=((double)dbytes + (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_high / 100.0);
+ scale_curve_for_vbv_compliancy(rc_2pass2_t * rc, const float fps)
+ {
+         /* correct any VBV violations. Peak bitrate violations disappears
+          * by this automatically
+          *
+          * This implementation follows
+          *
+          * Westerink, Rajagopalan, Gonzales "Two-pass MPEG-2 variable-bitrate encoding"
+          * IBM J. RES. DEVELOP. VOL 43, No. 4, July 1999, p.471--488
+          *
+          * Thanks, guys! This paper rocks!!! */
+         /* For each scene of len N, we have to check up to N^2 possible buffer fills.
+          * This works well with MPEG-2 where N==12 or so, but for MPEG-4 it's a
+          * little slow...
+          *
+          * TODO: Better control on VBVfill between scenes */
+         const float vbv_size = (float)rc->param.vbv_size/8.f;
+         const float vbv_initial = (float)rc->param.vbv_initial/8.f;
+         const float maxrate = 0.9f*rc->param.vbv_maxrate;
+         const float vbv_low = 0.10f*vbv_size;
+         const float r0 = (int)(maxrate/fps+0.5)/8.f;
+         int i,k,l,n,violation = 0;
+         float *scenefactor;
+         int *scenestart;
+         int *scenelength;
+         /* first step: determine how many "scenes" there are and store their
+          * boundaries we could get all this from existing keyframe_positions,
+          * somehow, but there we don't have a min_scenelength, and it's no big
+          * deal to get it again. */
+         const int min_scenelength = (int)(fps+0.5);
+         int num_scenes = 0;
+         int last_scene = -999;
+         for (i=0; i<rc->num_frames; i++) {
+                 if ((rc->stats[i].type == XVID_TYPE_IVOP) && (i-last_scene>min_scenelength)) {
+                         last_scene = i;
+                         num_scenes++;
+                 }
+         }
+         scenefactor = (float*)malloc(num_scenes*sizeof(float));
+         scenestart = (int*)malloc(num_scenes*sizeof(int));
+         scenelength = (int*)malloc(num_scenes*sizeof(int));
+         if ((!scenefactor) || (!scenestart) || (!scenelength) ) {
+                 free(scenefactor);
+                 free(scenestart);
+                 free(scenelength);
+                 /* remember: free(0) is valid and does exactly nothing. */
+                 return(-1);
+         }
+         /* count again and safe the length/position */
+         num_scenes = 0;
+         last_scene = -999;
+         for (i=0; i<rc->num_frames; i++) {
+                 if ((rc->stats[i].type == XVID_TYPE_IVOP) && (i-last_scene>min_scenelength)) {
+                         if (num_scenes>0) {
+                                 scenelength[num_scenes-1]=i-last_scene;
+                         }
+                         scenestart[num_scenes]=i;
+                         num_scenes++;
+                         last_scene = i;
+                 }
+         }
+         scenelength[num_scenes-1]=i-last_scene;
+         /* second step: check for each scene, how much we can scale its frames up or
+          * down such that the VBV restriction is just fulfilled */
+ #define R(k,n) (((n)+1-(k))*r0)     /* how much enters the buffer between frame k and n */
+         for (l=0; l<num_scenes;l++) {
+                 const int start = scenestart[l];
+                 const int length = scenelength[l];
+                 twopass_stat_t * frames = &rc->stats[start];
+                 float S0n,Skn;
+                 float f,minf = 99999.f;
+                 S0n=0.;
+                 for (n=0;n<=length-1;n++) {
+                         S0n += frames[n].scaled_length;
+                         k = 0;
+                         Skn = S0n;
+                         f = (R(k,n-1) + (vbv_initial - vbv_low)) / Skn;
+                         if (f < minf)
+                                 minf = f;
+                         for (k=1;k<=n;k++) {
+                                 Skn -= frames[k].scaled_length;
+                                 f = (R(k,n-1) + (vbv_size - vbv_low)) / Skn;
+                                 if (f < minf)
+                                         minf = f;
+                         }
+                 }
+                 /* special case: at the end, fill buffer up to vbv_initial again
+                  *
+                  * TODO: Allow other values for buffer fill between scenes
+                  * e.g. if n=N is smallest f-value, then check for better value */
+                 n=length;
+                 k=0;
+                 Skn = S0n;
+                 f = R(k,n-1)/Skn;
+                 if (f < minf)
+                         minf = f;
+                 for (k=1;k<=n-1;k++) {
+                         Skn -= frames[k].scaled_length;
+                         f = (R(k,n-1) + (vbv_initial - vbv_low)) / Skn;
+                         if (f < minf)
+                                 minf = f;
+                 }
+                 DPRINTF(XVID_DEBUG_RC, "[xvid rc] Scene %d (Frames %d-%d): VBVfactor %f\n",
+                                 l, start, start+length-1 , minf);
+                 scenefactor[l] = minf;
+         }
+ #undef R
+         /* last step: now we know of any scene how much it can be scaled up or down
+          * without violating VBV. Next, distribute bits from the evil scenes to the
+          * good ones */
+         do {
+                 float S_red = 0.f;    /* how much to redistribute */
+                 float S_elig = 0.f;   /* sum of bit for those scenes you can still swallow something*/
+                 float f_red;
+                 int l;
+                 /* check how much is wrong */
+                 for (l=0;l<num_scenes;l++) {
+                         const int start = scenestart[l];
+                         const int length = scenelength[l];
+                         twopass_stat_t * frames = &rc->stats[start];
+                         /* exactly 1 means "don't touch this anymore!" */
+                         if (scenefactor[l] == 1.)
+                                 continue;
+                         /* within limits */
+                         if (scenefactor[l] > 1.) {
+                                 for (n= 0; n < length; n++)
+                                         S_elig += frames[n].scaled_length;
                          } else {
-                                 dbytes2 = ((double)dbytes + (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_low / 100.0);
+                                 /* underflowing segment */
+                                 for (n= 0; n < length; n++) {
+                                         float newbytes = (float)frames[n].scaled_length * scenefactor[l];
+                                         S_red += (float)frames[n].scaled_length - (float)newbytes;
+                                         frames[n].scaled_length =(int)newbytes;
+                                 }
+                                 scenefactor[l] = 1.f;
+                         }
                          }
-                         if (dbytes2 < rc->min_length[s->type-1])
+                 /* no more underflows */
-                                     dbytes2 = rc->min_length[s->type-1];
+                 if (S_red < 1.f)
+                         break;
-             total2 += dbytes2;
+                 if (S_elig < 1.f) {
+                         DPRINTF(XVID_DEBUG_RC, "[xvid rc] Everything underflowing.\n");
+                         free(scenefactor);
+                         free(scenestart);
+                         free(scenelength);
+                         return(-2);
          }
+                 f_red = (1.f + S_red/S_elig);
+                 DPRINTF(XVID_DEBUG_RC, "[xvid rc] Moving %.0f kB to avoid buffer underflow, correction factor: %.5f\n",
+                                 S_red/1024.f, f_red);
+                 violation=0;
+                 /* scale remaining scenes up to meet total size */
+                 for (l=0; l<num_scenes; l++) {
+                         const int start = scenestart[l];
+                         const int length = scenelength[l];
+                         twopass_stat_t * frames = &rc->stats[start];
+                         if (scenefactor[l] == 1.)
+                                 continue;
+                         /* there shouldn't be any segments with factor<1 left, so all the rest is >1 */
+                         for (n= 0; n < length; n++) {
+                                 frames[n].scaled_length = (int)(frames[n].scaled_length * f_red + 0.5);
      }
-     rc->curve_comp_scale = total1 / total2;
+                         scenefactor[l] /= f_red;
+                         if (scenefactor[l] < 1.f)
+                                 violation=1;
+                 }
-         DPRINTF(XVID_DEBUG_RC, "middle frame size for asymmetric curve compression: pframe%d bframe:%d\n",
+         } while (violation);
-             (int)(rc->avg_length[XVID_TYPE_PVOP-1] * rc->curve_comp_scale),
-                         (int)(rc->avg_length[XVID_TYPE_BVOP-1] * rc->curve_comp_scale));
-     rc->overflow = 0;
+         free(scenefactor);
-     rc->KFoverflow = 0;
+         free(scenestart);
-     rc->KFoverflow_partial = 0;
+         free(scenelength);
-     rc->KF_idx = 1;
+         return(0);
  }
+ /*****************************************************************************
+  * Still more low level stuff (nothing to do with stats treatment)
+  ****************************************************************************/
+ /* This function returns an allocated string containing a complete line read
+  * from the file starting at the current position */
+ static char *
+ readline(FILE *f)
+ {
+         char *buffer = NULL;
+         int buffer_size = 0;
+         int pos = 0;
+         do {
+                 int c;
+                 /* Read a character from the stream */
+                 c = fgetc(f);
+                 /* Is that EOF or new line ? */
+                 if(c == EOF || c == '\n')
+                         break;
+                 /* Do we have to update buffer ? */
+                 if(pos >= buffer_size - 1) {
+                         buffer_size += BUF_SZ;
+                         buffer = (char*)realloc(buffer, buffer_size);
+                         if (buffer == NULL)
+                                 return(NULL);
+                 }
+                 buffer[pos] = c;
+                 pos++;
+         } while(1);
+         /* Read \n or EOF */
+         if (buffer == NULL) {
+                 /* EOF, so we reached the end of the file, return NULL */
+                 if(feof(f))
+                         return(NULL);
+                 /* Just an empty line with just a newline, allocate a 1 byte buffer to
+                  * store a zero length string */
+                 buffer = (char*)malloc(1);
+                 if(buffer == NULL)
+                         return(NULL);
+         }
+         /* Zero terminated string */
+         buffer[pos] = '\0';
+         return(buffer);
+ }
+ /* This function returns a pointer to the first non space char in the given
+  * string */
+ static char *
+ skipspaces(char *string)
+ {
+         const char spaces[] =
+                 {
+                         ' ','\t','\0'
+                 };
+         const char *spacechar = spaces;
+         if (string == NULL) return(NULL);
+         while (*string != '\0') {
+                 /* Test against space chars */
+                 while (*spacechar != '\0') {
+                         if (*string == *spacechar) {
+                                 string++;
+                                 spacechar = spaces;
+                                 break;
+                         }
+                         spacechar++;
+                 }
+                 /* No space char */
+                 if (*spacechar == '\0') return(string);
+         }
+         return(string);
+ }
+ /* This function returns a boolean that tells if the string is only a
+  * comment */
+ static int
+ iscomment(char *string)
+ {
+         const char comments[] =
+                 {
+                         '#',';', '%', '\0'
+                 };
+         const char *cmtchar = comments;
+         int iscomment = 0;
+         if (string == NULL) return(1);
+         string = skipspaces(string);
+         while(*cmtchar != '\0') {
+                 if(*string == *cmtchar) {
+                         iscomment = 1;
+                         break;
+                 }
+                 cmtchar++;
+         }
+         return(iscomment);
+ }
+ #if 0
+ static void
+ stats_print(rc_2pass2_t * rc)
+ {
+         int i;
+         const char frame_type[4] = { 'i', 'p', 'b', 's'};
+         for (i=0; i<rc->num_frames; i++) {
+                 twopass_stat_t *s = &rc->stats[i];
+                 DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- frame:%d type:%c quant:%d stats:%d scaled:%d desired:%d actual:%d overflow(%c):%.2f\n",
+                                 i, frame_type[s->type-1], -1, s->length, s->scaled_length,
+                                 s->desired_length, -1, frame_type[s->type-1], -1.0f);
+         }
+ }
+ #endif

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