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revision 1.1, Tue Mar 25 10:58:33 2003 UTC revision 1.1.2.34, Wed Jan 7 13:51:24 2004 UTC
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1    /******************************************************************************
2     *
3     *  XviD Bit Rate Controller Library
4     *  - VBR 2 pass bitrate controller implementation -
5     *
6     *  Copyright (C)      2002 Foxer <email?>
7     *                     2002 Dirk Knop <dknop@gwdg.de>
8     *                2002-2003 Edouard Gomez <ed.gomez@free.fr>
9     *                     2003 Pete Ross <pross@xvid.org>
10     *
11     *  This curve treatment algorithm is the one originally implemented by Foxer
12     *  and tuned by Dirk Knop for the XviD vfw frontend.
13     *
14     *  This program is free software; you can redistribute it and/or modify
15     *  it under the terms of the GNU General Public License as published by
16     *  the Free Software Foundation; either version 2 of the License, or
17     *  (at your option) any later version.
18     *
19     *  This program is distributed in the hope that it will be useful,
20     *  but WITHOUT ANY WARRANTY; without even the implied warranty of
21     *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22     *  GNU General Public License for more details.
23     *
24     *  You should have received a copy of the GNU General Public License
25     *  along with this program; if not, write to the Free Software
26     *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
27     *
28     * $Id$
29     *
30     *****************************************************************************/
31    
32    #define BQUANT_PRESCALE
33    #undef COMPENSATE_FORMULA
34    
35    /* forces second pass not to be bigger than first */
36    #undef PASS_SMALLER
37    
38    #include <stdio.h>
39    #include <math.h>
40    #include <limits.h>
41    
42    #include "../xvid.h"
43    #include "../image/image.h"
44    
45    /*****************************************************************************
46     * Some default settings
47     ****************************************************************************/
48    
49    #define DEFAULT_KEYFRAME_BOOST 0
50    #define DEFAULT_OVERFLOW_CONTROL_STRENGTH 10
51    #define DEFAULT_CURVE_COMPRESSION_HIGH 0
52    #define DEFAULT_CURVE_COMPRESSION_LOW 0
53    #define DEFAULT_MAX_OVERFLOW_IMPROVEMENT 10
54    #define DEFAULT_MAX_OVERFLOW_DEGRADATION 10
55    
56    /* Keyframe settings */
57    #define DEFAULT_KFREDUCTION 20
58    #define DEFAULT_KFTHRESHOLD 1
59    
60    /*****************************************************************************
61     * Some default constants (can be tuned)
62     ****************************************************************************/
63    
64    /* Specify the invariant part of the headers bits (header+MV)
65     * as  hlength/cst */
66    #define INVARIANT_HEADER_PART_IVOP 1 /* factor 1.0f   */
67    #define INVARIANT_HEADER_PART_PVOP 2 /* factor 0.5f   */
68    #define INVARIANT_HEADER_PART_BVOP 8 /* factor 0.125f */
69    
70    /*****************************************************************************
71     * Structures
72     ****************************************************************************/
73    
74    /* Statistics */
75    typedef struct {
76            int type;               /* first pass type */
77            int quant;              /* first pass quant */
78            int blks[3];            /* k,m,y blks */
79            int length;             /* first pass length */
80            int invariant;          /* what we assume as being invariant between the two passes, it's a sub part of header + MV bits */
81            int scaled_length;      /* scaled length */
82            int desired_length;     /* desired length; calculated during encoding */
83            int error;
84    
85            int zone_mode;   /* XVID_ZONE_xxx */
86            double weight;
87    } twopass_stat_t;
88    
89    /* Context struct */
90    typedef struct
91    {
92            xvid_plugin_2pass2_t param;
93    
94            /*----------------------------------
95             * constant statistical data
96             *--------------------------------*/
97    
98            /* Number of frames of the sequence */
99            int num_frames;
100    
101            /* Number of Intra frames of the sequence */
102            int num_keyframes;
103    
104            /* Target filesize to reach */
105            uint64_t target;
106    
107            /* Count of each frame types */
108            int count[3];
109    
110            /* Total length of each frame types (1st pass) */
111            uint64_t tot_length[3];
112            uint64_t tot_invariant[3];
113    
114            /* Average length of each frame types (used first for 1st pass data and
115             * then for scaled averages */
116            double avg_length[3];
117    
118            /* Minimum frame length allowed for each frame type */
119            int min_length[3];
120    
121            /* Total bytes per frame type once the curve has been scaled
122             * NB: advanced parameters do not change this value. This field
123             *     represents the total scaled w/o any advanced settings */
124            uint64_t tot_scaled_length[3];
125    
126            /* Maximum observed frame size observed during the first pass, the RC
127             * will try tp force all frame sizes in the second pass to be under that
128             * limit */
129            int max_length;
130    
131            /*----------------------------------
132             * Zones statistical data
133             *--------------------------------*/
134    
135            /* Total length used by XVID_ZONE_QUANT zones */
136            uint64_t tot_quant;
137            uint64_t tot_quant_invariant;
138    
139            /* Holds the total amount of frame bytes, zone weighted (only scalable
140             * part of frame bytes) */
141            uint64_t tot_weighted;
142    
143            /*----------------------------------
144             * Advanced settings helper ratios
145             *--------------------------------*/
146    
147            /* This the ratio that has to be applied to all p/b frames in order
148             * to reserve/retrieve bits for/from keyframe boosting and consecutive
149             * keyframe penalty */
150            double pb_iboost_tax_ratio;
151    
152            /* This the ratio to apply to all b/p frames in order to respect the
153             * assymetric curve compression while respecting a target filesize
154             * NB: The assymetric delta gain has to be computed before this ratio
155             *     is applied, and then the delta is added to the scaled size */
156            double assymetric_tax_ratio;
157    
158            /*----------------------------------
159             * Data from the stats file kept
160             * into RAM for easy access
161             *--------------------------------*/
162    
163            /* Array of keyframe locations
164             * eg: rc->keyframe_locations[100] returns the frame number of the 100th
165             *     keyframe */
166            int *keyframe_locations;
167    
168            /* Index of the last keyframe used in the keyframe_location */
169            int KF_idx;
170    
171            /* Array of all 1st pass data file -- see the twopass_stat_t structure
172             * definition for more details */
173            twopass_stat_t * stats;
174    
175            /*----------------------------------
176             * Histerysis helpers
177             *--------------------------------*/
178    
179            /* This field holds the int2float conversion errors of each quant per
180             * frame type, this allow the RC to keep track of rouding error and thus
181             * increase or decrease the chosen quant according to this residue */
182            double quant_error[3][32];
183    
184            /* This fields stores the count of each quant usage per frame type
185             * No real role but for debugging */
186            int quant_count[3][32];
187    
188            /* Last valid quantizer used per frame type, it allows quantizer
189             * increament/decreament limitation in order to avoid big image quality
190             * "jumps" */
191            int last_quant[3];
192    
193            /*----------------------------------
194             * Overflow control
195             *--------------------------------*/
196    
197            /* Current overflow that has to be distributed to p/b frames */
198            double overflow;
199    
200            /* Total overflow for keyframes -- not distributed directly */
201            double KFoverflow;
202    
203            /* Amount of keyframe overflow to introduce to the global p/b frame
204             * overflow counter at each encoded frame */
205            double KFoverflow_partial;
206    
207            /* Unknown ???
208             * ToDo: description */
209            double fq_error;
210    
211            /*----------------------------------
212             * Debug
213             *--------------------------------*/
214            double desired_total;
215            double real_total;
216    } rc_2pass2_t;
217    
218    
219    /*****************************************************************************
220     * Sub plugin functions prototypes
221     ****************************************************************************/
222    
223    static int rc_2pass2_create(xvid_plg_create_t * create, rc_2pass2_t ** handle);
224    static int rc_2pass2_before(rc_2pass2_t * rc, xvid_plg_data_t * data);
225    static int rc_2pass2_after(rc_2pass2_t * rc, xvid_plg_data_t * data);
226    static int rc_2pass2_destroy(rc_2pass2_t * rc, xvid_plg_destroy_t * destroy);
227    
228    /*****************************************************************************
229     * Plugin definition
230     ****************************************************************************/
231    
232    int
233    xvid_plugin_2pass2(void * handle, int opt, void * param1, void * param2)
234    {
235            switch(opt) {
236            case XVID_PLG_INFO :
237            case XVID_PLG_FRAME :
238                    return 0;
239    
240            case XVID_PLG_CREATE :
241                    return rc_2pass2_create((xvid_plg_create_t*)param1, param2);
242    
243            case XVID_PLG_DESTROY :
244                    return rc_2pass2_destroy((rc_2pass2_t*)handle, (xvid_plg_destroy_t*)param1);
245    
246            case XVID_PLG_BEFORE :
247                    return rc_2pass2_before((rc_2pass2_t*)handle, (xvid_plg_data_t*)param1);
248    
249            case XVID_PLG_AFTER :
250                    return rc_2pass2_after((rc_2pass2_t*)handle, (xvid_plg_data_t*)param1);
251            }
252    
253            return XVID_ERR_FAIL;
254    }
255    
256    /*****************************************************************************
257     * Sub plugin functions definitions
258     ****************************************************************************/
259    
260    /* First a few local helping function prototypes */
261    static  int statsfile_count_frames(rc_2pass2_t * rc, char * filename);
262    static  int statsfile_load(rc_2pass2_t *rc, char * filename);
263    static void zone_process(rc_2pass2_t *rc, const xvid_plg_create_t * create);
264    static void first_pass_stats_prepare_data(rc_2pass2_t * rc);
265    static void first_pass_scale_curve_internal(rc_2pass2_t *rc);
266    static void scaled_curve_apply_advanced_parameters(rc_2pass2_t * rc);
267    #if 0
268    static void stats_print(rc_2pass2_t * rc);
269    #endif
270    
271    /*----------------------------------------------------------------------------
272     *--------------------------------------------------------------------------*/
273    
274    static int
275    rc_2pass2_create(xvid_plg_create_t * create, rc_2pass2_t **handle)
276    {
277            xvid_plugin_2pass2_t * param = (xvid_plugin_2pass2_t *)create->param;
278            rc_2pass2_t * rc;
279            int i;
280    
281            rc = malloc(sizeof(rc_2pass2_t));
282            if (rc == NULL)
283                    return XVID_ERR_MEMORY;
284    
285            rc->param = *param;
286    
287            /* Initialize all defaults */
288    #define _INIT(a, b) if((a) <= 0) (a) = (b)
289            /* Let's set our defaults if needed */
290            _INIT(rc->param.keyframe_boost, DEFAULT_KEYFRAME_BOOST);
291            _INIT(rc->param.overflow_control_strength, DEFAULT_OVERFLOW_CONTROL_STRENGTH);
292            _INIT(rc->param.curve_compression_high, DEFAULT_CURVE_COMPRESSION_HIGH);
293            _INIT(rc->param.curve_compression_low, DEFAULT_CURVE_COMPRESSION_LOW);
294            _INIT(rc->param.max_overflow_improvement, DEFAULT_MAX_OVERFLOW_IMPROVEMENT);
295            _INIT(rc->param.max_overflow_degradation,  DEFAULT_MAX_OVERFLOW_DEGRADATION);
296    
297            /* Keyframe settings */
298            _INIT(rc->param.kfreduction, DEFAULT_KFREDUCTION);
299            _INIT(rc->param.kfthreshold, DEFAULT_KFTHRESHOLD);
300    #undef _INIT
301    
302            /* Initialize some stuff to zero */
303            for(i=0; i<3; i++) {
304                    int j;
305                    for (j=0; j<32; j++) {
306                            rc->quant_error[i][j] = 0;
307                            rc->quant_count[i][j] = 0;
308                    }
309            }
310    
311            for (i=0; i<3; i++) rc->last_quant[i] = 0;
312    
313            rc->fq_error = 0;
314    
315            /* Count frames (and intra frames) in the stats file, store the result into
316             * the rc structure */
317            if (statsfile_count_frames(rc, param->filename) == -1) {
318                    DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- ERROR: fopen %s failed\n", param->filename);
319                    free(rc);
320                    return(XVID_ERR_FAIL);
321            }
322    
323            /* Allocate the stats' memory */
324            if ((rc->stats = malloc(rc->num_frames * sizeof(twopass_stat_t))) == NULL) {
325                    free(rc);
326                    return(XVID_ERR_MEMORY);
327            }
328    
329            /* Allocate keyframes location's memory
330             * PS: see comment in pre_process0 for the +1 location requirement */
331            rc->keyframe_locations = malloc((rc->num_keyframes + 1) * sizeof(int));
332            if (rc->keyframe_locations == NULL) {
333                    free(rc->stats);
334                    free(rc);
335                    return(XVID_ERR_MEMORY);
336            }
337    
338            /* Load the first pass stats */
339            if (statsfile_load(rc, param->filename) == -1) {
340                    DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- ERROR: fopen %s failed\n", param->filename);
341                    free(rc->keyframe_locations);
342                    free(rc->stats);
343                    free(rc);
344                    return XVID_ERR_FAIL;
345            }
346    
347            /* Compute the target filesize */
348            if (rc->param.bitrate<0) {
349                    /* if negative, bitrate equals the target (in kbytes) */
350                    rc->target = ((uint64_t)(-rc->param.bitrate)) * 1024;
351            } else if (rc->num_frames  < create->fbase/create->fincr) {
352                    /* Source sequence is less than 1s long, we do as if it was 1s long */
353                    rc->target = rc->param.bitrate / 8;
354            } else {
355                    /* Target filesize = bitrate/8 * numframes / framerate */
356                    rc->target =
357                            ((uint64_t)rc->param.bitrate * (uint64_t)rc->num_frames * \
358                             (uint64_t)create->fincr) / \
359                            ((uint64_t)create->fbase * 8);
360            }
361    
362            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Frame rate: %d/%d (%ffps)\n",
363                            create->fbase, create->fincr,
364                            (double)create->fbase/(double)create->fincr);
365            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Number of frames: %d\n", rc->num_frames);
366            if(rc->param.bitrate>=0)
367                    DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Target bitrate: %ld\n", rc->param.bitrate);
368            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Target filesize: %lld\n", rc->target);
369    
370            /* Compensate the average frame overhead caused by the container */
371            rc->target -= rc->num_frames*rc->param.container_frame_overhead;
372            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Container Frame overhead: %d\n", rc->param.container_frame_overhead);
373            if(rc->param.container_frame_overhead)
374                    DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- New target filesize after container compensation: %lld\n", rc->target);
375    
376            /* When bitrate is not given it means it has been scaled by an external
377             * application */
378            if (rc->param.bitrate) {
379                    /* Apply zone settings
380                     * - set rc->tot_quant which represents the total num of bytes spent in
381                     *   fixed quant zones
382                     * - set rc->tot_weighted which represents the total amount of bytes
383                     *   spent in normal or weighted zones in first pass (normal zones can
384                     *   be considered weight=1)
385                     * - set rc->tot_quant_invariant which represents the total num of bytes
386                     *   spent in fixed quant zones for headers */
387                    zone_process(rc, create);
388            } else {
389                    /* External scaling -- zones are ignored */
390                    for (i=0;i<rc->num_frames;i++) {
391                            rc->stats[i].zone_mode = XVID_ZONE_WEIGHT;
392                            rc->stats[i].weight = 1.0;
393                    }
394                    rc->tot_quant = 0;
395            }
396    
397            /* Gathers some information about first pass stats:
398             *  - finds the minimum frame length for each frame type during 1st pass.
399             *     rc->min_size[]
400             *  - determines the maximum frame length observed (no frame type distinction).
401             *     rc->max_size
402             *  - count how many times each frame type has been used.
403             *     rc->count[]
404             *  - total bytes used per frame type
405             *     rc->tot_length[]
406             *  - total bytes considered invariant between the 2 passes
407             *  - store keyframe location
408             *     rc->keyframe_locations[]
409             */
410            first_pass_stats_prepare_data(rc);
411    
412            /* If we have a user bitrate, it means it's an internal curve scaling */
413            if (rc->param.bitrate) {
414                    /* Perform internal curve scaling */
415                    first_pass_scale_curve_internal(rc);
416            }
417    
418            /* Apply advanced curve options, and compute some parameters in order to
419             * shape the curve in the BEFORE/AFTER pair of functions */
420            scaled_curve_apply_advanced_parameters(rc);
421    
422            *handle = rc;
423            return(0);
424    }
425    
426    /*----------------------------------------------------------------------------
427     *--------------------------------------------------------------------------*/
428    
429    static int
430    rc_2pass2_destroy(rc_2pass2_t * rc, xvid_plg_destroy_t * destroy)
431    {
432            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- target_total:%lld desired_total:%.2f (%.2f%%) actual_total:%.2f (%.2f%%)\n",
433                            rc->target,
434                            rc->desired_total,
435                            100*rc->desired_total/(double)rc->target,
436                            rc->real_total,
437                            100*rc->real_total/(double)rc->target);
438    
439            free(rc->keyframe_locations);
440            free(rc->stats);
441            free(rc);
442            return(0);
443    }
444    
445    /*----------------------------------------------------------------------------
446     *--------------------------------------------------------------------------*/
447    
448    static int
449    rc_2pass2_before(rc_2pass2_t * rc, xvid_plg_data_t * data)
450    {
451            twopass_stat_t * s = &rc->stats[data->frame_num];
452            double dbytes;
453            double scaled_quant;
454            double overflow;
455            int capped_to_max_framesize = 0;
456    
457            /* This function is quite long but easy to understand. In order to simplify
458             * the code path (a bit), we treat 3 cases that can return immediatly. */
459    
460            /* First case: Another plugin has already set a quantizer */
461            if (data->quant > 0)
462                    return(0);
463    
464            /* Second case: insufficent stats data
465             * We can't guess much what we should do, let core decide all alone */
466            if (data->frame_num >= rc->num_frames) {
467                    DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- stats file too short (now processing frame %d)",
468                            data->frame_num);
469                    return(0);
470            }
471    
472            /* Third case: We are in a Quant zone
473             * Quant zones must just ensure we use the same settings as first pass
474             * So set the quantizer and the type */
475            if (s->zone_mode == XVID_ZONE_QUANT) {
476                    /* Quant stuff */
477                    rc->fq_error += s->weight;
478                    data->quant = (int)rc->fq_error;
479                    rc->fq_error -= data->quant;
480    
481                    /* The type stuff */
482                    data->type = s->type;
483    
484                    /* The only required data for AFTER step is this one for the overflow
485                     * control */
486                    s->desired_length = s->length;
487    
488                    return(0);
489            }
490    
491    
492            /*************************************************************************/
493            /*************************************************************************/
494            /*************************************************************************/
495    
496            /*-------------------------------------------------------------------------
497             * Frame bit allocation first part
498             *
499             * First steps apply user settings, just like it is done in the theoritical
500             * scaled_curve_apply_advanced_parameters
501             *-----------------------------------------------------------------------*/
502    
503            /* Set desired to what we are wanting to obtain for this frame */
504            dbytes = (double)s->scaled_length;
505    
506            /* IFrame user settings*/
507            if (s->type == XVID_TYPE_IVOP) {
508                    /* Keyframe boosting -- All keyframes benefit from it */
509                    dbytes += dbytes*rc->param.keyframe_boost / 100;
510    
511    #if 0 /* ToDo: decide how to apply kfthresholding */
512    #endif
513            } else {
514    
515                    /* P/S/B frames must reserve some bits for iframe boosting */
516                    dbytes *= rc->pb_iboost_tax_ratio;
517    
518                    /* Apply assymetric curve compression */
519                    if (rc->param.curve_compression_high || rc->param.curve_compression_low) {
520                            double assymetric_delta;
521    
522                            /* Compute the assymetric delta, this is computed before applying
523                             * the tax, as done in the pre_process function */
524                            if (dbytes > rc->avg_length[s->type-1])
525                                    assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_high / 100.0;
526                            else
527                                    assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_low  / 100.0;
528    
529                            /* Now we must apply the assymetric tax, else our curve compression
530                             * would not give a theoritical target size equal to what it is
531                             * expected */
532                            dbytes *= rc->assymetric_tax_ratio;
533    
534                            /* Now we can add the assymetric delta */
535                            dbytes += assymetric_delta;
536                    }
537            }
538    
539            /* That is what we would like to have -- Don't put that chunk after
540             * overflow control, otherwise, overflow is counted twice and you obtain
541             * half sized bitrate sequences */
542            s->desired_length  = (int)dbytes;
543            rc->desired_total += dbytes;
544    
545            /*------------------------------------------------------------------------
546             * Frame bit allocation: overflow control part.
547             *
548             * Unlike the theoritical scaled_curve_apply_advanced_parameters, here
549             * it's real encoding and we need to make sure we don't go so far from
550             * what is our ideal scaled curve.
551             *-----------------------------------------------------------------------*/
552    
553            /* Compute the overflow we should compensate */
554            if (s->type != XVID_TYPE_IVOP || rc->overflow > 0) {
555                    double frametype_factor;
556                    double framesize_factor;
557    
558                    /* Take only the desired part of overflow */
559                    overflow = rc->overflow;
560    
561                    /* Factor that will take care to decrease the overflow applied
562                     * according to the importance of this frame type in term of
563                     * overall size */
564                    frametype_factor  = rc->count[XVID_TYPE_IVOP-1]*rc->avg_length[XVID_TYPE_IVOP-1];
565                    frametype_factor += rc->count[XVID_TYPE_PVOP-1]*rc->avg_length[XVID_TYPE_PVOP-1];
566                    frametype_factor += rc->count[XVID_TYPE_BVOP-1]*rc->avg_length[XVID_TYPE_BVOP-1];
567                    frametype_factor /= rc->count[s->type-1]*rc->avg_length[s->type-1];
568                    frametype_factor  = 1/frametype_factor;
569    
570                    /* Factor that will take care not to compensate too much for this frame
571                     * size */
572                    framesize_factor  = dbytes;
573                    framesize_factor /= rc->avg_length[s->type-1];
574    
575                    /* Treat only the overflow part concerned by this frame type and size */
576                    overflow *= frametype_factor;
577    #if 0
578                    /* Leave this one alone, as it impacts badly on quality */
579                    overflow *= framesize_factor;
580    #endif
581    
582                    /* Apply the overflow strength imposed by the user */
583                    overflow *= (rc->param.overflow_control_strength/100.0f);
584            } else {
585                    /* no negative overflow applied in IFrames because:
586                     *  - their role is important as they're references for P/BFrames.
587                     *  - there aren't much in typical sequences, so if an IFrame overflows too
588                     *    much, this overflow may impact the next IFrame too much and generate
589                     *    a sequence of poor quality frames */
590                    overflow = 0;
591            }
592    
593            /* Make sure we are not trying to compensate more overflow than we even have */
594            if (fabs(overflow) > fabs(rc->overflow))
595                    overflow = rc->overflow;
596    
597            /* Make sure the overflow doesn't make the frame size to get out of the range
598             * [-max_degradation..+max_improvment] */
599            if (overflow > dbytes*rc->param.max_overflow_improvement / 100) {
600                    if(overflow <= dbytes)
601                            dbytes += dbytes * rc->param.max_overflow_improvement / 100;
602                    else
603                            dbytes += overflow * rc->param.max_overflow_improvement / 100;
604            } else if (overflow < - dbytes * rc->param.max_overflow_degradation / 100) {
605                    dbytes -= dbytes * rc->param.max_overflow_degradation / 100;
606            } else {
607                    dbytes += overflow;
608            }
609    
610            /*-------------------------------------------------------------------------
611             * Frame bit allocation last part:
612             *
613             * Cap frame length so we don't reach neither bigger frame sizes than first
614             * pass nor smaller than the allowed minimum.
615             *-----------------------------------------------------------------------*/
616    
617    #ifdef PASS_SMALLER
618            if (dbytes > s->length) {
619                    dbytes = s->length;
620            } else
621    #endif
622                    if (dbytes < rc->min_length[s->type-1]) {
623                    dbytes = rc->min_length[s->type-1];
624            } else if (dbytes > rc->max_length) {
625                    /* ToDo: this condition is always wrong as max_length == maximum frame
626                     * length of first pass, so the first condition already caps the frame
627                     * size... */
628                    capped_to_max_framesize = 1;
629                    dbytes = rc->max_length;
630                    DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- frame:%d Capped to maximum frame size\n",
631                                    data->frame_num);
632            }
633    
634            /*------------------------------------------------------------------------
635             * Desired frame length <-> quantizer mapping
636             *-----------------------------------------------------------------------*/
637    
638    #ifdef BQUANT_PRESCALE
639            /* For bframes we prescale the quantizer to avoid too high quant scaling */
640            if(s->type == XVID_TYPE_BVOP) {
641    
642                    twopass_stat_t *b_ref = s;
643    
644                    /* Find the reference frame */
645                    while(b_ref != &rc->stats[0] && b_ref->type == XVID_TYPE_BVOP)
646                            b_ref--;
647    
648                    /* Compute the original quant */
649                    s->quant  = 2*(100*s->quant - data->bquant_offset);
650                    s->quant += data->bquant_ratio - 1; /* to avoid rounding issues */
651                    s->quant  = s->quant/data->bquant_ratio - b_ref->quant;
652            }
653    #endif
654    
655            /* Don't laugh at this very 'simple' quant<->size relationship, it
656             * proves to be acurate enough for our algorithm */
657            scaled_quant = (double)s->quant*(double)s->length/(double)dbytes;
658    
659    #ifdef COMPENSATE_FORMULA
660            /* We know xvidcore will apply the bframe formula again, so we compensate
661             * it right now to make sure we would not apply it twice */
662            if(s->type == XVID_TYPE_BVOP) {
663    
664                    twopass_stat_t *b_ref = s;
665    
666                    /* Find the reference frame */
667                    while(b_ref != &rc->stats[0] && b_ref->type == XVID_TYPE_BVOP)
668                            b_ref--;
669    
670                    /* Compute the quant it would be if the core did not apply the bframe
671                     * formula */
672                    scaled_quant  = 100*scaled_quant - data->bquant_offset;
673                    scaled_quant += data->bquant_ratio - 1; /* to avoid rouding issues */
674                    scaled_quant /= data->bquant_ratio;
675            }
676    #endif
677    
678            /* Quantizer has been scaled using floating point operations/results, we
679             * must cast it to integer */
680            data->quant = (int)scaled_quant;
681    
682            /* Let's clip the computed quantizer, if needed */
683            if (data->quant < 1) {
684                    data->quant = 1;
685            } else if (data->quant > 31) {
686                    data->quant = 31;
687            } else {
688    
689                    /* The frame quantizer has not been clipped, this appears to be a good
690                     * computed quantizer, do not loose quantizer decimal part that we
691                     * accumulate for later reuse when its sum represents a complete
692                     * unit. */
693                    rc->quant_error[s->type-1][data->quant] += scaled_quant - (double)data->quant;
694    
695                    if (rc->quant_error[s->type-1][data->quant] >= 1.0) {
696                            rc->quant_error[s->type-1][data->quant] -= 1.0;
697                            data->quant++;
698                    } else if (rc->quant_error[s->type-1][data->quant] <= -1.0) {
699                            rc->quant_error[s->type-1][data->quant] += 1.0;
700                            data->quant--;
701                    }
702            }
703    
704            /* Now we have a computed quant that is in the right quante range, with a
705             * possible +1 correction due to cumulated error. We can now safely clip
706             * the quantizer again with user's quant ranges. "Safely" means the Rate
707             * Control could learn more about this quantizer, this knowledge is useful
708             * for future frames even if it this quantizer won't be really used atm,
709             * that's why we don't perform this clipping earlier. */
710            if (data->quant < data->min_quant[s->type-1]) {
711                    data->quant = data->min_quant[s->type-1];
712            } else if (data->quant > data->max_quant[s->type-1]) {
713                    data->quant = data->max_quant[s->type-1];
714            }
715    
716            /* To avoid big quality jumps from frame to frame, we apply a "security"
717             * rule that makes |last_quant - new_quant| <= 2. This rule only applies
718             * to predicted frames (P and B) */
719            if (s->type != XVID_TYPE_IVOP && rc->last_quant[s->type-1] && capped_to_max_framesize == 0) {
720    
721                    if (data->quant > rc->last_quant[s->type-1] + 2) {
722                            data->quant = rc->last_quant[s->type-1] + 2;
723                            DPRINTF(XVID_DEBUG_RC,
724                                            "[xvid rc] -- frame %d p/b-frame quantizer prevented from rising too steeply\n",
725                                            data->frame_num);
726                    }
727                    if (data->quant < rc->last_quant[s->type-1] - 2) {
728                            data->quant = rc->last_quant[s->type-1] - 2;
729                            DPRINTF(XVID_DEBUG_RC,
730                                            "[xvid rc] -- frame:%d p/b-frame quantizer prevented from falling too steeply\n",
731                                            data->frame_num);
732                    }
733            }
734    
735            /* We don't want to pollute the RC histerisis when our computed quant has
736             * been computed from a capped frame size */
737            if (capped_to_max_framesize == 0)
738                    rc->last_quant[s->type-1] = data->quant;
739    
740            /* Don't forget to force 1st pass frame type ;-) */
741            data->type = s->type;
742    
743            return 0;
744    }
745    
746    /*----------------------------------------------------------------------------
747     *--------------------------------------------------------------------------*/
748    
749    static int
750    rc_2pass2_after(rc_2pass2_t * rc, xvid_plg_data_t * data)
751    {
752            const char frame_type[4] = { 'i', 'p', 'b', 's'};
753            twopass_stat_t * s = &rc->stats[data->frame_num];
754    
755            /* Insufficent stats data */
756            if (data->frame_num >= rc->num_frames)
757                    return 0;
758    
759            /* Update the quantizer counter */
760            rc->quant_count[s->type-1][data->quant]++;
761    
762            /* Update the frame type overflow */
763            if (data->type == XVID_TYPE_IVOP) {
764                    int kfdiff = 0;
765    
766                    if(rc->KF_idx != rc->num_frames -1) {
767                            kfdiff  = rc->keyframe_locations[rc->KF_idx+1];
768                            kfdiff -= rc->keyframe_locations[rc->KF_idx];
769                    }
770    
771                    /* Flush Keyframe overflow accumulator */
772                    rc->overflow += rc->KFoverflow;
773    
774                    /* Store the frame overflow to the keyframe accumulator */
775                    rc->KFoverflow = s->desired_length - data->length;
776    
777                    if (kfdiff > 1) {
778                            /* Non-consecutive keyframes case:
779                             * We can then divide this total keyframe overflow into equal parts
780                             * that we will distribute into regular overflow at each frame
781                             * between the sequence bounded by two IFrames */
782                            rc->KFoverflow_partial = rc->KFoverflow / (kfdiff - 1);
783                    } else {
784                            /* Consecutive keyframes case:
785                             * Flush immediatly the keyframe overflow and reset keyframe
786                             * overflow */
787                            rc->overflow += rc->KFoverflow;
788                            rc->KFoverflow = 0;
789                            rc->KFoverflow_partial = 0;
790                    }
791                    rc->KF_idx++;
792            } else {
793                    /* Accumulate the frame overflow */
794                    rc->overflow += s->desired_length - data->length;
795    
796                    /* Distribute part of the keyframe overflow */
797                    rc->overflow += rc->KFoverflow_partial;
798    
799                    /* Don't forget to substract that same amount from the total keyframe
800                     * overflow */
801                    rc->KFoverflow -= rc->KFoverflow_partial;
802            }
803    
804            rc->overflow += (s->error = s->desired_length - data->length);
805            rc->real_total += data->length;
806    
807            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",
808                            data->frame_num,
809                            frame_type[data->type-1],
810                            data->quant,
811                            s->length,
812                            s->scaled_length,
813                            s->desired_length,
814                            s->desired_length - s->error,
815                            -s->error,
816                            rc->overflow);
817    
818            return(0);
819    }
820    
821    /*****************************************************************************
822     * Helper functions definition
823     ****************************************************************************/
824    
825    /* Default buffer size for reading lines */
826    #define BUF_SZ   1024
827    
828    /* Helper functions for reading/parsing the stats file */
829    static char *skipspaces(char *string);
830    static int iscomment(char *string);
831    static char *readline(FILE *f);
832    
833    /* This function counts the number of frame entries in the stats file
834     * It also counts the number of I Frames */
835    static int
836    statsfile_count_frames(rc_2pass2_t * rc, char * filename)
837    {
838            FILE * f;
839            char *line;
840            int lines;
841    
842            rc->num_frames = 0;
843            rc->num_keyframes = 0;
844    
845            if ((f = fopen(filename, "rb")) == NULL)
846                    return(-1);
847    
848            lines = 0;
849            while ((line = readline(f)) != NULL) {
850    
851                    char *ptr;
852                    char type;
853                    int fields;
854    
855                    lines++;
856    
857                    /* We skip spaces */
858                    ptr = skipspaces(line);
859    
860                    /* Skip coment lines or empty lines */
861                    if(iscomment(ptr) || *ptr == '\0') {
862                            free(line);
863                            continue;
864                    }
865    
866                    /* Read the stat line from buffer */
867                    fields = sscanf(ptr, "%c", &type);
868    
869                    /* Valid stats files have at least 7 fields */
870                    if (fields == 1) {
871                            switch(type) {
872                            case 'i':
873                            case 'I':
874                                    rc->num_keyframes++;
875                            case 'p':
876                            case 'P':
877                            case 'b':
878                            case 'B':
879                            case 's':
880                            case 'S':
881                                    rc->num_frames++;
882                                    break;
883                            default:
884                                    DPRINTF(XVID_DEBUG_RC,
885                                                    "[xvid rc] -- WARNING: L%d unknown frame type used (%c).\n",
886                                                    lines, type);
887                            }
888                    } else {
889                                    DPRINTF(XVID_DEBUG_RC,
890                                                    "[xvid rc] -- WARNING: L%d misses some stat fields (%d).\n",
891                                                    lines, 7-fields);
892                    }
893    
894                    /* Free the line buffer */
895                    free(line);
896            }
897    
898            /* We are done with the file */
899            fclose(f);
900    
901            return(0);
902    }
903    
904    /* open stats file(s) and read into rc->stats array */
905    static int
906    statsfile_load(rc_2pass2_t *rc, char * filename)
907    {
908            FILE * f;
909            int processed_entries;
910    
911            /* Opens the file */
912            if ((f = fopen(filename, "rb"))==NULL)
913                    return(-1);
914    
915            processed_entries = 0;
916            while(processed_entries < rc->num_frames) {
917                    char type;
918                    int fields;
919                    twopass_stat_t * s = &rc->stats[processed_entries];
920                    char *line, *ptr;
921    
922                    /* Read the line from the file */
923                    if((line = readline(f)) == NULL)
924                            break;
925    
926                    /* We skip spaces */
927                    ptr = skipspaces(line);
928    
929                    /* Skip comment lines or empty lines */
930                    if(iscomment(ptr) || *ptr == '\0') {
931                            free(line);
932                            continue;
933                    }
934    
935                    /* Reset this field that is optional */
936                    s->scaled_length = 0;
937    
938                    /* Convert the fields */
939                    fields = sscanf(ptr,
940                                                    "%c %d %d %d %d %d %d %d\n",
941                                                    &type,
942                                                    &s->quant,
943                                                    &s->blks[0], &s->blks[1], &s->blks[2],
944                                                    &s->length, &s->invariant /* not really yet */,
945                                                    &s->scaled_length);
946    
947                    /* Free line buffer, we don't need it anymore */
948                    free(line);
949    
950                    /* Fail silently, this has probably been warned in
951                     * statsfile_count_frames */
952                    if(fields != 7 && fields != 8)
953                            continue;
954    
955                    /* Convert frame type and compute the invariant length part */
956                    switch(type) {
957                    case 'i':
958                    case 'I':
959                            s->type = XVID_TYPE_IVOP;
960                            s->invariant /= INVARIANT_HEADER_PART_IVOP;
961                            break;
962                    case 'p':
963                    case 'P':
964                    case 's':
965                    case 'S':
966                            s->type = XVID_TYPE_PVOP;
967                            s->invariant /= INVARIANT_HEADER_PART_PVOP;
968                            break;
969                    case 'b':
970                    case 'B':
971                            s->type = XVID_TYPE_BVOP;
972                            s->invariant /= INVARIANT_HEADER_PART_BVOP;
973                            break;
974                    default:
975                            /* Same as before, fail silently */
976                            continue;
977                    }
978    
979                    /* Ok it seems it's been processed correctly */
980                    processed_entries++;
981            }
982    
983            /* Close the file */
984            fclose(f);
985    
986            return(0);
987    }
988    
989    /* pre-process the statistics data
990     * - for each type, count, tot_length, min_length, max_length
991     * - set keyframes_locations, tot_prescaled */
992    static void
993    first_pass_stats_prepare_data(rc_2pass2_t * rc)
994    {
995            int i,j;
996    
997            /* *rc fields initialization
998             * NB: INT_MAX and INT_MIN are used in order to be immediately replaced
999             *     with real values of the 1pass */
1000            for (i=0; i<3; i++) {
1001                    rc->count[i]=0;
1002                    rc->tot_length[i] = 0;
1003                    rc->tot_invariant[i] = 0;
1004                    rc->min_length[i] = INT_MAX;
1005            }
1006    
1007            rc->max_length = INT_MIN;
1008            rc->tot_weighted = 0;
1009    
1010            /* Loop through all frames and find/compute all the stuff this function
1011             * is supposed to do */
1012            for (i=j=0; i<rc->num_frames; i++) {
1013                    twopass_stat_t * s = &rc->stats[i];
1014    
1015                    rc->count[s->type-1]++;
1016                    rc->tot_length[s->type-1] += s->length;
1017                    rc->tot_invariant[s->type-1] += s->invariant;
1018                    if (s->zone_mode != XVID_ZONE_QUANT)
1019                            rc->tot_weighted += (int)(s->weight*(s->length - s->invariant));
1020    
1021                    if (s->length < rc->min_length[s->type-1]) {
1022                            rc->min_length[s->type-1] = s->length;
1023                    }
1024    
1025                    if (s->length > rc->max_length) {
1026                            rc->max_length = s->length;
1027                    }
1028    
1029                    if (s->type == XVID_TYPE_IVOP) {
1030                            rc->keyframe_locations[j] = i;
1031                            j++;
1032                    }
1033            }
1034    
1035            /* NB:
1036             * The "per sequence" overflow system considers a natural sequence to be
1037             * formed by all frames between two iframes, so if we want to make sure
1038             * the system does not go nuts during last sequence, we force the last
1039             * frame to appear in the keyframe locations array. */
1040            rc->keyframe_locations[j] = i;
1041    
1042            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Min 1st pass IFrame length: %d\n", rc->min_length[0]);
1043            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Min 1st pass PFrame length: %d\n", rc->min_length[1]);
1044            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Min 1st pass BFrame length: %d\n", rc->min_length[2]);
1045    }
1046    
1047    /* calculate zone weight "center" */
1048    static void
1049    zone_process(rc_2pass2_t *rc, const xvid_plg_create_t * create)
1050    {
1051            int i,j;
1052            int n = 0;
1053    
1054            rc->tot_quant = 0;
1055            rc->tot_quant_invariant = 0;
1056    
1057            if (create->num_zones == 0) {
1058                    for (j = 0; j < rc->num_frames; j++) {
1059                            rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
1060                            rc->stats[j].weight = 1.0;
1061                    }
1062                    n += rc->num_frames;
1063            }
1064    
1065    
1066            for(i=0; i < create->num_zones; i++) {
1067    
1068                    int next = (i+1<create->num_zones) ? create->zones[i+1].frame : rc->num_frames;
1069    
1070                    /* Zero weight make no sense */
1071                    if (create->zones[i].increment == 0) create->zones[i].increment = 1;
1072                    /* And obviously an undetermined infinite makes even less sense */
1073                    if (create->zones[i].base == 0) create->zones[i].base = 1;
1074    
1075                    if (i==0 && create->zones[i].frame > 0) {
1076                            for (j = 0; j < create->zones[i].frame && j < rc->num_frames; j++) {
1077                                    rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
1078                                    rc->stats[j].weight = 1.0;
1079                            }
1080                            n += create->zones[i].frame;
1081                    }
1082    
1083                    if (create->zones[i].mode == XVID_ZONE_WEIGHT) {
1084                            for (j = create->zones[i].frame; j < next && j < rc->num_frames; j++ ) {
1085                                    rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
1086                                    rc->stats[j].weight = (double)create->zones[i].increment / (double)create->zones[i].base;
1087                            }
1088                            next -= create->zones[i].frame;
1089                            n += next;
1090                    } else{  /* XVID_ZONE_QUANT */
1091                            for (j = create->zones[i].frame; j < next && j < rc->num_frames; j++ ) {
1092                                    rc->stats[j].zone_mode = XVID_ZONE_QUANT;
1093                                    rc->stats[j].weight = (double)create->zones[i].increment / (double)create->zones[i].base;
1094                                    rc->tot_quant += rc->stats[j].length;
1095                                    rc->tot_quant_invariant += rc->stats[j].invariant;
1096                            }
1097                    }
1098            }
1099    }
1100    
1101    
1102    /* scale the curve */
1103    static void
1104    first_pass_scale_curve_internal(rc_2pass2_t *rc)
1105    {
1106            int64_t target;
1107            int64_t total_invariant;
1108            double scaler;
1109            int i, num_MBs;
1110    
1111            /* We only scale texture data ! */
1112            total_invariant  = rc->tot_invariant[XVID_TYPE_IVOP-1];
1113            total_invariant += rc->tot_invariant[XVID_TYPE_PVOP-1];
1114            total_invariant += rc->tot_invariant[XVID_TYPE_BVOP-1];
1115            /* don't forget to substract header bytes used in quant zones, otherwise we
1116             * counting them twice */
1117            total_invariant -= rc->tot_quant_invariant;
1118    
1119            /* We remove the bytes used by the fixed quantizer zones during first pass
1120             * with the same quants, so we know very precisely how much that
1121             * represents */
1122            target  = rc->target;
1123            target -= rc->tot_quant;
1124    
1125            /* Let's compute a linear scaler in order to perform curve scaling */
1126            scaler = (double)(target - total_invariant) / (double)(rc->tot_weighted);
1127    
1128            /* Compute min frame lengths (for each frame type) according to the number
1129             * of MBs. We sum all block type counters of frame 0, this gives us the
1130             * number of MBs.
1131             *
1132             * We compare these hardcoded values with observed values in first pass
1133             * (determined in pre_process0).Then we keep the real minimum. */
1134    
1135            /* Number of MBs */
1136            num_MBs  = rc->stats[0].blks[0];
1137            num_MBs += rc->stats[0].blks[1];
1138            num_MBs += rc->stats[0].blks[2];
1139    
1140            /* Minimum for I frames */
1141            if(rc->min_length[XVID_TYPE_IVOP-1] > ((num_MBs*22) + 240) / 8)
1142                    rc->min_length[XVID_TYPE_IVOP-1] = ((num_MBs*22) + 240) / 8;
1143    
1144            /* Minimum for P/S frames */
1145            if(rc->min_length[XVID_TYPE_PVOP-1] > ((num_MBs) + 88)  / 8)
1146                    rc->min_length[XVID_TYPE_PVOP-1] = ((num_MBs) + 88)  / 8;
1147    
1148            /* Minimum for B frames */
1149            if(rc->min_length[XVID_TYPE_BVOP-1] > 8)
1150                    rc->min_length[XVID_TYPE_BVOP-1] = 8;
1151    
1152            /* Perform an initial scale pass.
1153             *
1154             * If a frame size is scaled underneath our hardcoded minimums, then we
1155             * force the frame size to the minimum, and deduct the original & scaled
1156             * frame length from the original and target total lengths */
1157            for (i=0; i<rc->num_frames; i++) {
1158                    twopass_stat_t * s = &rc->stats[i];
1159                    int len;
1160    
1161                    /* No need to scale frame length for which a specific quantizer is
1162                     * specified thanks to zones */
1163                    if (s->zone_mode == XVID_ZONE_QUANT) {
1164                            s->scaled_length = s->length;
1165                            continue;
1166                    }
1167    
1168                    /* Compute the scaled length -- only non invariant data length is scaled */
1169                    len = s->invariant + (int)((double)(s->length-s->invariant) * scaler * s->weight);
1170    
1171                    /* Compare with the computed minimum */
1172                    if (len < rc->min_length[s->type-1]) {
1173                            /* This is a 'forced size' frame, set its frame size to the
1174                             * computed minimum */
1175                            s->scaled_length = rc->min_length[s->type-1];
1176    
1177                            /* Remove both scaled and original size from their respective
1178                             * total counters, as we prepare a second pass for 'regular'
1179                             * frames */
1180                            target -= s->scaled_length;
1181                    } else {
1182                            /* Do nothing for now, we'll scale this later */
1183                            s->scaled_length = 0;
1184                    }
1185            }
1186    
1187            /* The first pass on data substracted all 'forced size' frames from the
1188             * total counters. Now, it's possible to scale the 'regular' frames. */
1189    
1190            /* Scaling factor for 'regular' frames */
1191            scaler = (double)(target - total_invariant) / (double)(rc->tot_weighted);
1192    
1193            /* Do another pass with the new scaler */
1194            for (i=0; i<rc->num_frames; i++) {
1195                    twopass_stat_t * s = &rc->stats[i];
1196    
1197                    /* Ignore frame with forced frame sizes */
1198                    if (s->scaled_length == 0)
1199                            s->scaled_length = s->invariant + (int)((double)(s->length-s->invariant) * scaler * s->weight);
1200            }
1201    
1202            /* Job done */
1203            return;
1204    }
1205    
1206    /* Apply all user settings to the scaled curve
1207     * This implies:
1208     *   keyframe boosting
1209     *   high/low compression */
1210    static void
1211    scaled_curve_apply_advanced_parameters(rc_2pass2_t * rc)
1212    {
1213            int i;
1214            int64_t ivop_boost_total;
1215    
1216            /* Reset the rate controller (per frame type) total byte counters */
1217            for (i=0; i<3; i++) rc->tot_scaled_length[i] = 0;
1218    
1219            /* Compute total bytes for each frame type */
1220            for (i=0; i<rc->num_frames;i++) {
1221                    twopass_stat_t *s = &rc->stats[i];
1222                    rc->tot_scaled_length[s->type-1] += s->scaled_length;
1223            }
1224    
1225            /* First we compute the total amount of bits needed, as being described by
1226             * the scaled distribution. During this pass over the complete stats data,
1227             * we see how much bits two user settings will get/give from/to p&b frames:
1228             *  - keyframe boosting
1229             *  - keyframe distance penalty */
1230            rc->KF_idx = 0;
1231            ivop_boost_total = 0;
1232            for (i=0; i<rc->num_frames; i++) {
1233                    twopass_stat_t * s = &rc->stats[i];
1234    
1235                    /* Some more work is needed for I frames */
1236                    if (s->type == XVID_TYPE_IVOP) {
1237                            int ivop_boost;
1238    
1239                            /* Accumulate bytes needed for keyframe boosting */
1240                            ivop_boost = s->scaled_length*rc->param.keyframe_boost/100;
1241    
1242    #if 0 /* ToDo: decide how to apply kfthresholding */
1243    #endif
1244                            /* If the frame size drops under the minimum length, then cap ivop_boost */
1245                            if (ivop_boost + s->scaled_length < rc->min_length[XVID_TYPE_IVOP-1])
1246                                    ivop_boost = rc->min_length[XVID_TYPE_IVOP-1] - s->scaled_length;
1247    
1248                            /* Accumulate the ivop boost */
1249                            ivop_boost_total += ivop_boost;
1250    
1251                            /* Don't forget to update the keyframe index */
1252                            rc->KF_idx++;
1253                    }
1254            }
1255    
1256            /* Initialize the IBoost tax ratio for P/S/B frames
1257             *
1258             * This ratio has to be applied to p/b/s frames in order to reserve
1259             * additional bits for keyframes (keyframe boosting) or if too much
1260             * keyframe distance is applied, bits retrieved from the keyframes.
1261             *
1262             * ie pb_length *= rc->pb_iboost_tax_ratio;
1263             *
1264             *    gives the ideal length of a p/b frame */
1265    
1266            /* Compute the total length of p/b/s frames (temporary storage into
1267             * movie_curve) */
1268            rc->pb_iboost_tax_ratio  = (double)rc->tot_scaled_length[XVID_TYPE_PVOP-1];
1269            rc->pb_iboost_tax_ratio += (double)rc->tot_scaled_length[XVID_TYPE_BVOP-1];
1270    
1271            /* Compute the ratio described above
1272             *     taxed_total = sum(0, n, tax*scaled_length)
1273             * <=> taxed_total = tax.sum(0, n, scaled_length)
1274             * <=> tax = taxed_total / original_total */
1275            rc->pb_iboost_tax_ratio =
1276                    (rc->pb_iboost_tax_ratio - ivop_boost_total) /
1277                    rc->pb_iboost_tax_ratio;
1278    
1279            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- IFrame boost tax ratio:%.2f\n",
1280                            rc->pb_iboost_tax_ratio);
1281    
1282            /* Compute the average size of frames per frame type */
1283            for(i=0; i<3; i++) {
1284                    /* Special case for missing type or weird case */
1285                    if (rc->count[i] == 0 || rc->pb_iboost_tax_ratio == 0) {
1286                            rc->avg_length[i] = 1;
1287                    } else {
1288                            rc->avg_length[i] = rc->tot_scaled_length[i];
1289    
1290                            if (i == (XVID_TYPE_IVOP-1)) {
1291                                    /* I Frames total has to be added the boost total */
1292                                    rc->avg_length[i] += ivop_boost_total;
1293                            } else {
1294                                    /* P/B frames has to taxed */
1295                                    rc->avg_length[i] *= rc->pb_iboost_tax_ratio;
1296                            }
1297    
1298                            /* Finally compute the average frame size */
1299                            rc->avg_length[i] /= (double)rc->count[i];
1300                    }
1301            }
1302    
1303            /* Assymetric curve compression */
1304            if (rc->param.curve_compression_high || rc->param.curve_compression_low) {
1305                    double symetric_total;
1306                    double assymetric_delta_total;
1307    
1308                    /* Like I frame boosting, assymetric curve compression modifies the total
1309                     * amount of needed bits, we must compute the ratio so we can prescale
1310                     lengths */
1311                    symetric_total = 0;
1312                    assymetric_delta_total = 0;
1313                    for (i=0; i<rc->num_frames; i++) {
1314                            double assymetric_delta;
1315                            double dbytes;
1316                            twopass_stat_t * s = &rc->stats[i];
1317    
1318                            /* I Frames are not concerned by assymetric scaling */
1319                            if (s->type == XVID_TYPE_IVOP)
1320                                    continue;
1321    
1322                            /* During the real run, we would have to apply the iboost tax */
1323                            dbytes = s->scaled_length * rc->pb_iboost_tax_ratio;
1324    
1325                            /* Update the symmetric curve compression total */
1326                            symetric_total += dbytes;
1327    
1328                            /* Apply assymetric curve compression */
1329                            if (dbytes > rc->avg_length[s->type-1])
1330                                    assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * (double)rc->param.curve_compression_high / 100.0f;
1331                            else
1332                                    assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * (double)rc->param.curve_compression_low  / 100.0f;
1333    
1334                            /* Cap to the minimum frame size if needed */
1335                            if (dbytes + assymetric_delta < rc->min_length[s->type-1])
1336                                    assymetric_delta = rc->min_length[s->type-1] - dbytes;
1337    
1338                            /* Accumulate after assymetric curve compression */
1339                            assymetric_delta_total += assymetric_delta;
1340                    }
1341    
1342                    /* Compute the tax that all p/b frames have to pay in order to respect the
1343                     * bit distribution changes that the assymetric compression curve imposes
1344                     * We want assymetric_total = sum(0, n-1, tax.scaled_length)
1345                     *      ie assymetric_total = ratio.sum(0, n-1, scaled_length)
1346                     *         ratio = assymetric_total / symmetric_total */
1347                    rc->assymetric_tax_ratio = ((double)symetric_total - (double)assymetric_delta_total) / (double)symetric_total;
1348            } else {
1349                    rc->assymetric_tax_ratio = 1.0f;
1350            }
1351    
1352            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Assymetric tax ratio:%.2f\n", rc->assymetric_tax_ratio);
1353    
1354            /* Last bits that need to be reset */
1355            rc->overflow = 0;
1356            rc->KFoverflow = 0;
1357            rc->KFoverflow_partial = 0;
1358            rc->KF_idx = 0;
1359            rc->desired_total = 0;
1360            rc->real_total = 0;
1361    
1362            /* Job done */
1363            return;
1364    }
1365    
1366    /*****************************************************************************
1367     * Still more low level stuff (nothing to do with stats treatment)
1368     ****************************************************************************/
1369    
1370    /* This function returns an allocated string containing a complete line read
1371     * from the file starting at the current position */
1372    static char *
1373    readline(FILE *f)
1374    {
1375            char *buffer = NULL;
1376            int buffer_size = 0;
1377            int pos = 0;
1378    
1379            do {
1380                    int c;
1381    
1382                    /* Read a character from the stream */
1383                    c = fgetc(f);
1384    
1385                    /* Is that EOF or new line ? */
1386                    if(c == EOF || c == '\n')
1387                            break;
1388    
1389                    /* Do we have to update buffer ? */
1390                    if(pos >= buffer_size - 1) {
1391                            buffer_size += BUF_SZ;
1392                            buffer = (char*)realloc(buffer, buffer_size);
1393                            if (buffer == NULL)
1394                                    return(NULL);
1395                    }
1396    
1397                    buffer[pos] = c;
1398                    pos++;
1399            } while(1);
1400    
1401            /* Read \n or EOF */
1402            if (buffer == NULL) {
1403                    /* EOF, so we reached the end of the file, return NULL */
1404                    if(feof(f))
1405                            return(NULL);
1406    
1407                    /* Just an empty line with just a newline, allocate a 1 byte buffer to
1408                     * store a zero length string */
1409                    buffer = (char*)malloc(1);
1410                    if(buffer == NULL)
1411                            return(NULL);
1412            }
1413    
1414            /* Zero terminated string */
1415            buffer[pos] = '\0';
1416    
1417            return(buffer);
1418    }
1419    
1420    /* This function returns a pointer to the first non space char in the given
1421     * string */
1422    static char *
1423    skipspaces(char *string)
1424    {
1425            const char spaces[] =
1426                    {
1427                            ' ','\t','\0'
1428                    };
1429            const char *spacechar = spaces;
1430    
1431            if (string == NULL) return(NULL);
1432    
1433            while (*string != '\0') {
1434                    /* Test against space chars */
1435                    while (*spacechar != '\0') {
1436                            if (*string == *spacechar) {
1437                                    string++;
1438                                    spacechar = spaces;
1439                                    break;
1440                            }
1441                            spacechar++;
1442                    }
1443    
1444                    /* No space char */
1445                    if (*spacechar == '\0') return(string);
1446            }
1447    
1448            return(string);
1449    }
1450    
1451    /* This function returns a boolean that tells if the string is only a
1452     * comment */
1453    static int
1454    iscomment(char *string)
1455    {
1456            const char comments[] =
1457                    {
1458                            '#',';', '%', '\0'
1459                    };
1460            const char *cmtchar = comments;
1461            int iscomment = 0;
1462    
1463            if (string == NULL) return(1);
1464    
1465            string = skipspaces(string);
1466    
1467            while(*cmtchar != '\0') {
1468                    if(*string == *cmtchar) {
1469                            iscomment = 1;
1470                            break;
1471                    }
1472                    cmtchar++;
1473            }
1474    
1475            return(iscomment);
1476    }
1477    
1478    #if 0
1479    static void
1480    stats_print(rc_2pass2_t * rc)
1481    {
1482            int i;
1483            const char frame_type[4] = { 'i', 'p', 'b', 's'};
1484    
1485            for (i=0; i<rc->num_frames; i++) {
1486                    twopass_stat_t *s = &rc->stats[i];
1487                    DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- frame:%d type:%c quant:%d stats:%d scaled:%d desired:%d actual:%d overflow(%c):%.2f\n",
1488                                    i, frame_type[s->type-1], -1, s->length, s->scaled_length,
1489                                    s->desired_length, -1, frame_type[s->type-1], -1.0f);
1490            }
1491    }
1492    #endif
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