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revision 1.1, Tue Mar 25 10:58:33 2003 UTC revision 1.2, Mon Mar 22 22:36:24 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    /* automtically alters overflow controls (strength and improvement/degradation)
39            to fight most common problems without user's knowladge */
40    #define SMART_OVERFLOW_SETTING
41    
42    #include <stdio.h>
43    #include <math.h>
44    #include <limits.h>
45    
46    #include "../xvid.h"
47    #include "../image/image.h"
48    
49    /*****************************************************************************
50     * Some default settings
51     ****************************************************************************/
52    
53    #define DEFAULT_KEYFRAME_BOOST 0
54    #define DEFAULT_OVERFLOW_CONTROL_STRENGTH 10
55    #define DEFAULT_CURVE_COMPRESSION_HIGH 0
56    #define DEFAULT_CURVE_COMPRESSION_LOW 0
57    #define DEFAULT_MAX_OVERFLOW_IMPROVEMENT 10
58    #define DEFAULT_MAX_OVERFLOW_DEGRADATION 10
59    
60    /* Keyframe settings */
61    #define DEFAULT_KFREDUCTION 20
62    #define DEFAULT_KFTHRESHOLD 1
63    
64    /*****************************************************************************
65     * Some default constants (can be tuned)
66     ****************************************************************************/
67    
68    /* Specify the invariant part of the headers bits (header+MV)
69     * as  hlength/cst */
70    #define INVARIANT_HEADER_PART_IVOP 1 /* factor 1.0f   */
71    #define INVARIANT_HEADER_PART_PVOP 2 /* factor 0.5f   */
72    #define INVARIANT_HEADER_PART_BVOP 8 /* factor 0.125f */
73    
74    /*****************************************************************************
75     * Structures
76     ****************************************************************************/
77    
78    /* Statistics */
79    typedef struct {
80            int type;               /* first pass type */
81            int quant;              /* first pass quant */
82            int blks[3];            /* k,m,y blks */
83            int length;             /* first pass length */
84            int invariant;          /* what we assume as being invariant between the two passes, it's a sub part of header + MV bits */
85            int scaled_length;      /* scaled length */
86            int desired_length;     /* desired length; calculated during encoding */
87            int error;
88    
89            int zone_mode;   /* XVID_ZONE_xxx */
90            double weight;
91    } twopass_stat_t;
92    
93    /* Context struct */
94    typedef struct
95    {
96            xvid_plugin_2pass2_t param;
97    
98            /*----------------------------------
99             * constant statistical data
100             *--------------------------------*/
101    
102            /* Number of frames of the sequence */
103            int num_frames;
104    
105            /* Number of Intra frames of the sequence */
106            int num_keyframes;
107    
108            /* Target filesize to reach */
109            uint64_t target;
110    
111            /* Count of each frame types */
112            int count[3];
113    
114            /* Total length of each frame types (1st pass) */
115            uint64_t tot_length[3];
116            uint64_t tot_invariant[3];
117    
118            /* Average length of each frame types (used first for 1st pass data and
119             * then for scaled averages */
120            double avg_length[3];
121    
122            /* Minimum frame length allowed for each frame type */
123            int min_length[3];
124    
125            /* Total bytes per frame type once the curve has been scaled
126             * NB: advanced parameters do not change this value. This field
127             *     represents the total scaled w/o any advanced settings */
128            uint64_t tot_scaled_length[3];
129    
130            /* Maximum observed frame size observed during the first pass, the RC
131             * will try tp force all frame sizes in the second pass to be under that
132             * limit */
133            int max_length;
134    
135            /*----------------------------------
136             * Zones statistical data
137             *--------------------------------*/
138    
139            /* Total length used by XVID_ZONE_QUANT zones */
140            uint64_t tot_quant;
141            uint64_t tot_quant_invariant;
142    
143            /* Holds the total amount of frame bytes, zone weighted (only scalable
144             * part of frame bytes) */
145            uint64_t tot_weighted;
146    
147            /*----------------------------------
148             * Advanced settings helper ratios
149             *--------------------------------*/
150    
151            /* This the ratio that has to be applied to all p/b frames in order
152             * to reserve/retrieve bits for/from keyframe boosting and consecutive
153             * keyframe penalty */
154            double pb_iboost_tax_ratio;
155    
156            /* This the ratio to apply to all b/p frames in order to respect the
157             * assymetric curve compression while respecting a target filesize
158             * NB: The assymetric delta gain has to be computed before this ratio
159             *     is applied, and then the delta is added to the scaled size */
160            double assymetric_tax_ratio;
161    
162            /*----------------------------------
163             * Data from the stats file kept
164             * into RAM for easy access
165             *--------------------------------*/
166    
167            /* Array of keyframe locations
168             * eg: rc->keyframe_locations[100] returns the frame number of the 100th
169             *     keyframe */
170            int *keyframe_locations;
171    
172            /* Index of the last keyframe used in the keyframe_location */
173            int KF_idx;
174    
175            /* Array of all 1st pass data file -- see the twopass_stat_t structure
176             * definition for more details */
177            twopass_stat_t * stats;
178    
179            /*----------------------------------
180             * Histerysis helpers
181             *--------------------------------*/
182    
183            /* This field holds the int2float conversion errors of each quant per
184             * frame type, this allow the RC to keep track of rouding error and thus
185             * increase or decrease the chosen quant according to this residue */
186            double quant_error[3][32];
187    
188            /* This fields stores the count of each quant usage per frame type
189             * No real role but for debugging */
190            int quant_count[3][32];
191    
192            /* Last valid quantizer used per frame type, it allows quantizer
193             * increament/decreament limitation in order to avoid big image quality
194             * "jumps" */
195            int last_quant[3];
196    
197            /*----------------------------------
198             * Overflow control
199             *--------------------------------*/
200    
201            /* Current overflow that has to be distributed to p/b frames */
202            double overflow;
203    
204            /* Total overflow for keyframes -- not distributed directly */
205            double KFoverflow;
206    
207            /* Amount of keyframe overflow to introduce to the global p/b frame
208             * overflow counter at each encoded frame */
209            double KFoverflow_partial;
210    
211            /* Unknown ???
212             * ToDo: description */
213            double fq_error;
214    
215            int min_quant; /* internal minimal quant, prevents wrong quants from being used */
216    
217            /*----------------------------------
218             * Debug
219             *--------------------------------*/
220            double desired_total;
221            double real_total;
222    } rc_2pass2_t;
223    
224    
225    /*****************************************************************************
226     * Sub plugin functions prototypes
227     ****************************************************************************/
228    
229    static int rc_2pass2_create(xvid_plg_create_t * create, rc_2pass2_t ** handle);
230    static int rc_2pass2_before(rc_2pass2_t * rc, xvid_plg_data_t * data);
231    static int rc_2pass2_after(rc_2pass2_t * rc, xvid_plg_data_t * data);
232    static int rc_2pass2_destroy(rc_2pass2_t * rc, xvid_plg_destroy_t * destroy);
233    
234    /*****************************************************************************
235     * Plugin definition
236     ****************************************************************************/
237    
238    int
239    xvid_plugin_2pass2(void * handle, int opt, void * param1, void * param2)
240    {
241            switch(opt) {
242            case XVID_PLG_INFO :
243            case XVID_PLG_FRAME :
244                    return 0;
245    
246            case XVID_PLG_CREATE :
247                    return rc_2pass2_create((xvid_plg_create_t*)param1, param2);
248    
249            case XVID_PLG_DESTROY :
250                    return rc_2pass2_destroy((rc_2pass2_t*)handle, (xvid_plg_destroy_t*)param1);
251    
252            case XVID_PLG_BEFORE :
253                    return rc_2pass2_before((rc_2pass2_t*)handle, (xvid_plg_data_t*)param1);
254    
255            case XVID_PLG_AFTER :
256                    return rc_2pass2_after((rc_2pass2_t*)handle, (xvid_plg_data_t*)param1);
257            }
258    
259            return XVID_ERR_FAIL;
260    }
261    
262    /*****************************************************************************
263     * Sub plugin functions definitions
264     ****************************************************************************/
265    
266    /* First a few local helping function prototypes */
267    static  int statsfile_count_frames(rc_2pass2_t * rc, char * filename);
268    static  int statsfile_load(rc_2pass2_t *rc, char * filename);
269    static void zone_process(rc_2pass2_t *rc, const xvid_plg_create_t * create);
270    static void first_pass_stats_prepare_data(rc_2pass2_t * rc);
271    static void first_pass_scale_curve_internal(rc_2pass2_t *rc);
272    static void scaled_curve_apply_advanced_parameters(rc_2pass2_t * rc);
273    #if 0
274    static void stats_print(rc_2pass2_t * rc);
275    #endif
276    
277    /*----------------------------------------------------------------------------
278     *--------------------------------------------------------------------------*/
279    
280    static int
281    rc_2pass2_create(xvid_plg_create_t * create, rc_2pass2_t **handle)
282    {
283            xvid_plugin_2pass2_t * param = (xvid_plugin_2pass2_t *)create->param;
284            rc_2pass2_t * rc;
285            int i;
286    
287            rc = malloc(sizeof(rc_2pass2_t));
288            if (rc == NULL)
289                    return XVID_ERR_MEMORY;
290    
291            rc->param = *param;
292    
293            /* Initialize all defaults */
294    #define _INIT(a, b) if((a) <= 0) (a) = (b)
295            /* Let's set our defaults if needed */
296            _INIT(rc->param.keyframe_boost, DEFAULT_KEYFRAME_BOOST);
297            _INIT(rc->param.overflow_control_strength, DEFAULT_OVERFLOW_CONTROL_STRENGTH);
298            _INIT(rc->param.curve_compression_high, DEFAULT_CURVE_COMPRESSION_HIGH);
299            _INIT(rc->param.curve_compression_low, DEFAULT_CURVE_COMPRESSION_LOW);
300            _INIT(rc->param.max_overflow_improvement, DEFAULT_MAX_OVERFLOW_IMPROVEMENT);
301            _INIT(rc->param.max_overflow_degradation,  DEFAULT_MAX_OVERFLOW_DEGRADATION);
302    
303            /* Keyframe settings */
304            _INIT(rc->param.kfreduction, DEFAULT_KFREDUCTION);
305            _INIT(rc->param.kfthreshold, DEFAULT_KFTHRESHOLD);
306    #undef _INIT
307    
308            /* Initialize some stuff to zero */
309            for(i=0; i<3; i++) {
310                    int j;
311                    for (j=0; j<32; j++) {
312                            rc->quant_error[i][j] = 0;
313                            rc->quant_count[i][j] = 0;
314                    }
315            }
316    
317            for (i=0; i<3; i++) rc->last_quant[i] = 0;
318    
319            rc->fq_error = 0;
320            rc->min_quant = 1;
321    
322            /* Count frames (and intra frames) in the stats file, store the result into
323             * the rc structure */
324            if (statsfile_count_frames(rc, param->filename) == -1) {
325                    DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- ERROR: fopen %s failed\n", param->filename);
326                    free(rc);
327                    return(XVID_ERR_FAIL);
328            }
329    
330            /* Allocate the stats' memory */
331            if ((rc->stats = malloc(rc->num_frames * sizeof(twopass_stat_t))) == NULL) {
332                    free(rc);
333                    return(XVID_ERR_MEMORY);
334            }
335    
336            /* Allocate keyframes location's memory
337             * PS: see comment in pre_process0 for the +1 location requirement */
338            rc->keyframe_locations = malloc((rc->num_keyframes + 1) * sizeof(int));
339            if (rc->keyframe_locations == NULL) {
340                    free(rc->stats);
341                    free(rc);
342                    return(XVID_ERR_MEMORY);
343            }
344    
345            /* Load the first pass stats */
346            if (statsfile_load(rc, param->filename) == -1) {
347                    DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- ERROR: fopen %s failed\n", param->filename);
348                    free(rc->keyframe_locations);
349                    free(rc->stats);
350                    free(rc);
351                    return XVID_ERR_FAIL;
352            }
353    
354            /* Compute the target filesize */
355            if (rc->param.bitrate<0) {
356                    /* if negative, bitrate equals the target (in kbytes) */
357                    rc->target = ((uint64_t)(-rc->param.bitrate)) * 1024;
358            } else if (rc->num_frames  < create->fbase/create->fincr) {
359                    /* Source sequence is less than 1s long, we do as if it was 1s long */
360                    rc->target = rc->param.bitrate / 8;
361            } else {
362                    /* Target filesize = bitrate/8 * numframes / framerate */
363                    rc->target =
364                            ((uint64_t)rc->param.bitrate * (uint64_t)rc->num_frames * \
365                             (uint64_t)create->fincr) / \
366                            ((uint64_t)create->fbase * 8);
367            }
368    
369            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Frame rate: %d/%d (%ffps)\n",
370                            create->fbase, create->fincr,
371                            (double)create->fbase/(double)create->fincr);
372            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Number of frames: %d\n", rc->num_frames);
373            if(rc->param.bitrate>=0)
374                    DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Target bitrate: %ld\n", rc->param.bitrate);
375            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Target filesize: %lld\n", rc->target);
376    
377            /* Compensate the average frame overhead caused by the container */
378            rc->target -= rc->num_frames*rc->param.container_frame_overhead;
379            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Container Frame overhead: %d\n", rc->param.container_frame_overhead);
380            if(rc->param.container_frame_overhead)
381                    DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- New target filesize after container compensation: %lld\n", rc->target);
382    
383            /* When bitrate is not given it means it has been scaled by an external
384             * application */
385            if (rc->param.bitrate) {
386                    /* Apply zone settings
387                     * - set rc->tot_quant which represents the total num of bytes spent in
388                     *   fixed quant zones
389                     * - set rc->tot_weighted which represents the total amount of bytes
390                     *   spent in normal or weighted zones in first pass (normal zones can
391                     *   be considered weight=1)
392                     * - set rc->tot_quant_invariant which represents the total num of bytes
393                     *   spent in fixed quant zones for headers */
394                    zone_process(rc, create);
395            } else {
396                    /* External scaling -- zones are ignored */
397                    for (i=0;i<rc->num_frames;i++) {
398                            rc->stats[i].zone_mode = XVID_ZONE_WEIGHT;
399                            rc->stats[i].weight = 1.0;
400                    }
401                    rc->tot_quant = 0;
402            }
403    
404            /* Gathers some information about first pass stats:
405             *  - finds the minimum frame length for each frame type during 1st pass.
406             *     rc->min_size[]
407             *  - determines the maximum frame length observed (no frame type distinction).
408             *     rc->max_size
409             *  - count how many times each frame type has been used.
410             *     rc->count[]
411             *  - total bytes used per frame type
412             *     rc->tot_length[]
413             *  - total bytes considered invariant between the 2 passes
414             *  - store keyframe location
415             *     rc->keyframe_locations[]
416             */
417            first_pass_stats_prepare_data(rc);
418    
419            /* If we have a user bitrate, it means it's an internal curve scaling */
420            if (rc->param.bitrate) {
421                    /* Perform internal curve scaling */
422                    first_pass_scale_curve_internal(rc);
423            }
424    
425            /* Apply advanced curve options, and compute some parameters in order to
426             * shape the curve in the BEFORE/AFTER pair of functions */
427            scaled_curve_apply_advanced_parameters(rc);
428    
429            *handle = rc;
430            return(0);
431    }
432    
433    /*----------------------------------------------------------------------------
434     *--------------------------------------------------------------------------*/
435    
436    static int
437    rc_2pass2_destroy(rc_2pass2_t * rc, xvid_plg_destroy_t * destroy)
438    {
439            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- target_total:%lld desired_total:%.2f (%.2f%%) actual_total:%.2f (%.2f%%)\n",
440                            rc->target,
441                            rc->desired_total,
442                            100*rc->desired_total/(double)rc->target,
443                            rc->real_total,
444                            100*rc->real_total/(double)rc->target);
445    
446            free(rc->keyframe_locations);
447            free(rc->stats);
448            free(rc);
449            return(0);
450    }
451    
452    /*----------------------------------------------------------------------------
453     *--------------------------------------------------------------------------*/
454    
455    static int
456    rc_2pass2_before(rc_2pass2_t * rc, xvid_plg_data_t * data)
457    {
458            twopass_stat_t * s = &rc->stats[data->frame_num];
459            double dbytes;
460            double scaled_quant;
461            double overflow;
462            int capped_to_max_framesize = 0;
463    
464            /* This function is quite long but easy to understand. In order to simplify
465             * the code path (a bit), we treat 3 cases that can return immediatly. */
466    
467            /* First case: Another plugin has already set a quantizer */
468            if (data->quant > 0)
469                    return(0);
470    
471            /* Second case: insufficent stats data
472             * We can't guess much what we should do, let core decide all alone */
473            if (data->frame_num >= rc->num_frames) {
474                    DPRINTF(XVID_DEBUG_RC,"[xvid rc] -- stats file too short (now processing frame %d)",
475                            data->frame_num);
476                    return(0);
477            }
478    
479            /* Third case: We are in a Quant zone
480             * Quant zones must just ensure we use the same settings as first pass
481             * So set the quantizer and the type */
482            if (s->zone_mode == XVID_ZONE_QUANT) {
483                    /* Quant stuff */
484                    rc->fq_error += s->weight;
485                    data->quant = (int)rc->fq_error;
486                    rc->fq_error -= data->quant;
487    
488                    /* The type stuff */
489                    data->type = s->type;
490    
491                    /* The only required data for AFTER step is this one for the overflow
492                     * control */
493                    s->desired_length = s->length;
494    
495                    return(0);
496            }
497    
498    
499            /*************************************************************************/
500            /*************************************************************************/
501            /*************************************************************************/
502    
503            /*-------------------------------------------------------------------------
504             * Frame bit allocation first part
505             *
506             * First steps apply user settings, just like it is done in the theoritical
507             * scaled_curve_apply_advanced_parameters
508             *-----------------------------------------------------------------------*/
509    
510            /* Set desired to what we are wanting to obtain for this frame */
511            dbytes = (double)s->scaled_length;
512    
513            /* IFrame user settings*/
514            if (s->type == XVID_TYPE_IVOP) {
515                    /* Keyframe boosting -- All keyframes benefit from it */
516                    dbytes += dbytes*rc->param.keyframe_boost / 100;
517    
518    #if 0 /* ToDo: decide how to apply kfthresholding */
519    #endif
520            } else {
521    
522                    /* P/S/B frames must reserve some bits for iframe boosting */
523                    dbytes *= rc->pb_iboost_tax_ratio;
524    
525                    /* Apply assymetric curve compression */
526                    if (rc->param.curve_compression_high || rc->param.curve_compression_low) {
527                            double assymetric_delta;
528    
529                            /* Compute the assymetric delta, this is computed before applying
530                             * the tax, as done in the pre_process function */
531                            if (dbytes > rc->avg_length[s->type-1])
532                                    assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_high / 100.0;
533                            else
534                                    assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_low  / 100.0;
535    
536                            /* Now we must apply the assymetric tax, else our curve compression
537                             * would not give a theoritical target size equal to what it is
538                             * expected */
539                            dbytes *= rc->assymetric_tax_ratio;
540    
541                            /* Now we can add the assymetric delta */
542                            dbytes += assymetric_delta;
543                    }
544            }
545    
546            /* That is what we would like to have -- Don't put that chunk after
547             * overflow control, otherwise, overflow is counted twice and you obtain
548             * half sized bitrate sequences */
549            s->desired_length  = (int)dbytes;
550            rc->desired_total += dbytes;
551    
552            /*------------------------------------------------------------------------
553             * Frame bit allocation: overflow control part.
554             *
555             * Unlike the theoritical scaled_curve_apply_advanced_parameters, here
556             * it's real encoding and we need to make sure we don't go so far from
557             * what is our ideal scaled curve.
558             *-----------------------------------------------------------------------*/
559    
560            /* Compute the overflow we should compensate */
561            if (s->type != XVID_TYPE_IVOP || rc->overflow > 0) {
562                    double frametype_factor;
563                    double framesize_factor;
564    
565                    /* Take only the desired part of overflow */
566                    overflow = rc->overflow;
567    
568                    /* Factor that will take care to decrease the overflow applied
569                     * according to the importance of this frame type in term of
570                     * overall size */
571                    frametype_factor  = rc->count[XVID_TYPE_IVOP-1]*rc->avg_length[XVID_TYPE_IVOP-1];
572                    frametype_factor += rc->count[XVID_TYPE_PVOP-1]*rc->avg_length[XVID_TYPE_PVOP-1];
573                    frametype_factor += rc->count[XVID_TYPE_BVOP-1]*rc->avg_length[XVID_TYPE_BVOP-1];
574                    frametype_factor /= rc->count[s->type-1]*rc->avg_length[s->type-1];
575                    frametype_factor  = 1/frametype_factor;
576    
577                    /* Factor that will take care not to compensate too much for this frame
578                     * size */
579                    framesize_factor  = dbytes;
580                    framesize_factor /= rc->avg_length[s->type-1];
581    
582                    /* Treat only the overflow part concerned by this frame type and size */
583                    overflow *= frametype_factor;
584    #if 0
585                    /* Leave this one alone, as it impacts badly on quality */
586                    overflow *= framesize_factor;
587    #endif
588    
589                    /* Apply the overflow strength imposed by the user */
590                    overflow *= (rc->param.overflow_control_strength/100.0f);
591            } else {
592                    /* no negative overflow applied in IFrames because:
593                     *  - their role is important as they're references for P/BFrames.
594                     *  - there aren't much in typical sequences, so if an IFrame overflows too
595                     *    much, this overflow may impact the next IFrame too much and generate
596                     *    a sequence of poor quality frames */
597                    overflow = 0;
598            }
599    
600            /* Make sure we are not trying to compensate more overflow than we even have */
601            if (fabs(overflow) > fabs(rc->overflow))
602                    overflow = rc->overflow;
603    
604            /* Make sure the overflow doesn't make the frame size to get out of the range
605             * [-max_degradation..+max_improvment] */
606            if (overflow > dbytes*rc->param.max_overflow_improvement / 100) {
607                    if(overflow <= dbytes)
608                            dbytes += dbytes * rc->param.max_overflow_improvement / 100;
609                    else
610                            dbytes += overflow * rc->param.max_overflow_improvement / 100;
611            } else if (overflow < - dbytes * rc->param.max_overflow_degradation / 100) {
612                    dbytes -= dbytes * rc->param.max_overflow_degradation / 100;
613            } else {
614                    dbytes += overflow;
615            }
616    
617            /*-------------------------------------------------------------------------
618             * Frame bit allocation last part:
619             *
620             * Cap frame length so we don't reach neither bigger frame sizes than first
621             * pass nor smaller than the allowed minimum.
622             *-----------------------------------------------------------------------*/
623    
624    #ifdef PASS_SMALLER
625            if (dbytes > s->length) {
626                    dbytes = s->length;
627            }
628    #endif
629    
630            /* Prevent stupid desired sizes under logical values */
631            if (dbytes < rc->min_length[s->type-1]) {
632                    dbytes = rc->min_length[s->type-1];
633            }
634    
635            /*------------------------------------------------------------------------
636             * Desired frame length <-> quantizer mapping
637             *-----------------------------------------------------------------------*/
638    
639    #ifdef BQUANT_PRESCALE
640            /* For bframes we prescale the quantizer to avoid too high quant scaling */
641            if(s->type == XVID_TYPE_BVOP) {
642    
643                    twopass_stat_t *b_ref = s;
644    
645                    /* Find the reference frame */
646                    while(b_ref != &rc->stats[0] && b_ref->type == XVID_TYPE_BVOP)
647                            b_ref--;
648    
649                    /* Compute the original quant */
650                    s->quant  = 2*(100*s->quant - data->bquant_offset);
651                    s->quant += data->bquant_ratio - 1; /* to avoid rounding issues */
652                    s->quant  = s->quant/data->bquant_ratio - b_ref->quant;
653            }
654    #endif
655    
656            /* Don't laugh at this very 'simple' quant<->size relationship, it
657             * proves to be acurate enough for our algorithm */
658            scaled_quant = (double)s->quant*(double)s->length/(double)dbytes;
659    
660    #ifdef COMPENSATE_FORMULA
661            /* We know xvidcore will apply the bframe formula again, so we compensate
662             * it right now to make sure we would not apply it twice */
663            if(s->type == XVID_TYPE_BVOP) {
664    
665                    twopass_stat_t *b_ref = s;
666    
667                    /* Find the reference frame */
668                    while(b_ref != &rc->stats[0] && b_ref->type == XVID_TYPE_BVOP)
669                            b_ref--;
670    
671                    /* Compute the quant it would be if the core did not apply the bframe
672                     * formula */
673                    scaled_quant  = 100*scaled_quant - data->bquant_offset;
674                    scaled_quant += data->bquant_ratio - 1; /* to avoid rouding issues */
675                    scaled_quant /= data->bquant_ratio;
676            }
677    #endif
678    
679            /* Quantizer has been scaled using floating point operations/results, we
680             * must cast it to integer */
681            data->quant = (int)scaled_quant;
682    
683            /* Let's clip the computed quantizer, if needed */
684            if (data->quant < 1) {
685                    data->quant = 1;
686            } else if (data->quant > 31) {
687                    data->quant = 31;
688            } else {
689    
690                    /* The frame quantizer has not been clipped, this appears to be a good
691                     * computed quantizer, do not loose quantizer decimal part that we
692                     * accumulate for later reuse when its sum represents a complete
693                     * unit. */
694                    rc->quant_error[s->type-1][data->quant] += scaled_quant - (double)data->quant;
695    
696                    if (rc->quant_error[s->type-1][data->quant] >= 1.0) {
697                            rc->quant_error[s->type-1][data->quant] -= 1.0;
698                            data->quant++;
699                    } else if (rc->quant_error[s->type-1][data->quant] <= -1.0) {
700                            rc->quant_error[s->type-1][data->quant] += 1.0;
701                            data->quant--;
702                    }
703            }
704    
705            /* Now we have a computed quant that is in the right quante range, with a
706             * possible +1 correction due to cumulated error. We can now safely clip
707             * the quantizer again with user's quant ranges. "Safely" means the Rate
708             * Control could learn more about this quantizer, this knowledge is useful
709             * for future frames even if it this quantizer won't be really used atm,
710             * that's why we don't perform this clipping earlier. */
711            if (data->quant < data->min_quant[s->type-1]) {
712                    data->quant = data->min_quant[s->type-1];
713            } else if (data->quant > data->max_quant[s->type-1]) {
714                    data->quant = data->max_quant[s->type-1];
715            }
716    
717            if (data->quant < rc->min_quant) data->quant = rc->min_quant;
718    
719            /* To avoid big quality jumps from frame to frame, we apply a "security"
720             * rule that makes |last_quant - new_quant| <= 2. This rule only applies
721             * to predicted frames (P and B) */
722            if (s->type != XVID_TYPE_IVOP && rc->last_quant[s->type-1] && capped_to_max_framesize == 0) {
723    
724                    if (data->quant > rc->last_quant[s->type-1] + 2) {
725                            data->quant = rc->last_quant[s->type-1] + 2;
726                            DPRINTF(XVID_DEBUG_RC,
727                                            "[xvid rc] -- frame %d p/b-frame quantizer prevented from rising too steeply\n",
728                                            data->frame_num);
729                    }
730                    if (data->quant < rc->last_quant[s->type-1] - 2) {
731                            data->quant = rc->last_quant[s->type-1] - 2;
732                            DPRINTF(XVID_DEBUG_RC,
733                                            "[xvid rc] -- frame:%d p/b-frame quantizer prevented from falling too steeply\n",
734                                            data->frame_num);
735                    }
736            }
737    
738            /* We don't want to pollute the RC histerisis when our computed quant has
739             * been computed from a capped frame size */
740            if (capped_to_max_framesize == 0)
741                    rc->last_quant[s->type-1] = data->quant;
742    
743            /* Don't forget to force 1st pass frame type ;-) */
744            data->type = s->type;
745    
746            return 0;
747    }
748    
749    /*----------------------------------------------------------------------------
750     *--------------------------------------------------------------------------*/
751    
752    static int
753    rc_2pass2_after(rc_2pass2_t * rc, xvid_plg_data_t * data)
754    {
755            const char frame_type[4] = { 'i', 'p', 'b', 's'};
756            twopass_stat_t * s = &rc->stats[data->frame_num];
757    
758            /* Insufficent stats data */
759            if (data->frame_num >= rc->num_frames)
760                    return 0;
761    
762            /* Update the quantizer counter */
763            rc->quant_count[s->type-1][data->quant]++;
764    
765            /* Update the frame type overflow */
766            if (data->type == XVID_TYPE_IVOP) {
767                    int kfdiff = 0;
768    
769                    if(rc->KF_idx != rc->num_frames -1) {
770                            kfdiff  = rc->keyframe_locations[rc->KF_idx+1];
771                            kfdiff -= rc->keyframe_locations[rc->KF_idx];
772                    }
773    
774                    /* Flush Keyframe overflow accumulator */
775                    rc->overflow += rc->KFoverflow;
776    
777                    /* Store the frame overflow to the keyframe accumulator */
778                    rc->KFoverflow = s->desired_length - data->length;
779    
780                    if (kfdiff > 1) {
781                            /* Non-consecutive keyframes case:
782                             * We can then divide this total keyframe overflow into equal parts
783                             * that we will distribute into regular overflow at each frame
784                             * between the sequence bounded by two IFrames */
785                            rc->KFoverflow_partial = rc->KFoverflow / (kfdiff - 1);
786                    } else {
787                            /* Consecutive keyframes case:
788                             * Flush immediatly the keyframe overflow and reset keyframe
789                             * overflow */
790                            rc->overflow += rc->KFoverflow;
791                            rc->KFoverflow = 0;
792                            rc->KFoverflow_partial = 0;
793                    }
794                    rc->KF_idx++;
795            } else {
796                    /* Accumulate the frame overflow */
797                    rc->overflow += s->desired_length - data->length;
798    
799                    /* Distribute part of the keyframe overflow */
800                    rc->overflow += rc->KFoverflow_partial;
801    
802                    /* Don't forget to substract that same amount from the total keyframe
803                     * overflow */
804                    rc->KFoverflow -= rc->KFoverflow_partial;
805            }
806    
807            rc->overflow += (s->error = s->desired_length - data->length);
808            rc->real_total += data->length;
809    
810            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",
811                            data->frame_num,
812                            frame_type[data->type-1],
813                            data->quant,
814                            s->length,
815                            s->scaled_length,
816                            s->desired_length,
817                            s->desired_length - s->error,
818                            -s->error,
819                            rc->overflow);
820    
821            return(0);
822    }
823    
824    /*****************************************************************************
825     * Helper functions definition
826     ****************************************************************************/
827    
828    /* Default buffer size for reading lines */
829    #define BUF_SZ   1024
830    
831    /* Helper functions for reading/parsing the stats file */
832    static char *skipspaces(char *string);
833    static int iscomment(char *string);
834    static char *readline(FILE *f);
835    
836    /* This function counts the number of frame entries in the stats file
837     * It also counts the number of I Frames */
838    static int
839    statsfile_count_frames(rc_2pass2_t * rc, char * filename)
840    {
841            FILE * f;
842            char *line;
843            int lines;
844    
845            rc->num_frames = 0;
846            rc->num_keyframes = 0;
847    
848            if ((f = fopen(filename, "rb")) == NULL)
849                    return(-1);
850    
851            lines = 0;
852            while ((line = readline(f)) != NULL) {
853    
854                    char *ptr;
855                    char type;
856                    int fields;
857    
858                    lines++;
859    
860                    /* We skip spaces */
861                    ptr = skipspaces(line);
862    
863                    /* Skip coment lines or empty lines */
864                    if(iscomment(ptr) || *ptr == '\0') {
865                            free(line);
866                            continue;
867                    }
868    
869                    /* Read the stat line from buffer */
870                    fields = sscanf(ptr, "%c", &type);
871    
872                    /* Valid stats files have at least 7 fields */
873                    if (fields == 1) {
874                            switch(type) {
875                            case 'i':
876                            case 'I':
877                                    rc->num_keyframes++;
878                            case 'p':
879                            case 'P':
880                            case 'b':
881                            case 'B':
882                            case 's':
883                            case 'S':
884                                    rc->num_frames++;
885                                    break;
886                            default:
887                                    DPRINTF(XVID_DEBUG_RC,
888                                                    "[xvid rc] -- WARNING: L%d unknown frame type used (%c).\n",
889                                                    lines, type);
890                            }
891                    } else {
892                                    DPRINTF(XVID_DEBUG_RC,
893                                                    "[xvid rc] -- WARNING: L%d misses some stat fields (%d).\n",
894                                                    lines, 7-fields);
895                    }
896    
897                    /* Free the line buffer */
898                    free(line);
899            }
900    
901            /* We are done with the file */
902            fclose(f);
903    
904            return(0);
905    }
906    
907    /* open stats file(s) and read into rc->stats array */
908    static int
909    statsfile_load(rc_2pass2_t *rc, char * filename)
910    {
911            FILE * f;
912            int processed_entries;
913    
914            /* Opens the file */
915            if ((f = fopen(filename, "rb"))==NULL)
916                    return(-1);
917    
918            processed_entries = 0;
919            while(processed_entries < rc->num_frames) {
920                    char type;
921                    int fields;
922                    twopass_stat_t * s = &rc->stats[processed_entries];
923                    char *line, *ptr;
924    
925                    /* Read the line from the file */
926                    if((line = readline(f)) == NULL)
927                            break;
928    
929                    /* We skip spaces */
930                    ptr = skipspaces(line);
931    
932                    /* Skip comment lines or empty lines */
933                    if(iscomment(ptr) || *ptr == '\0') {
934                            free(line);
935                            continue;
936                    }
937    
938                    /* Reset this field that is optional */
939                    s->scaled_length = 0;
940    
941                    /* Convert the fields */
942                    fields = sscanf(ptr,
943                                                    "%c %d %d %d %d %d %d %d\n",
944                                                    &type,
945                                                    &s->quant,
946                                                    &s->blks[0], &s->blks[1], &s->blks[2],
947                                                    &s->length, &s->invariant /* not really yet */,
948                                                    &s->scaled_length);
949    
950                    /* Free line buffer, we don't need it anymore */
951                    free(line);
952    
953                    /* Fail silently, this has probably been warned in
954                     * statsfile_count_frames */
955                    if(fields != 7 && fields != 8)
956                            continue;
957    
958                    /* Convert frame type and compute the invariant length part */
959                    switch(type) {
960                    case 'i':
961                    case 'I':
962                            s->type = XVID_TYPE_IVOP;
963                            s->invariant /= INVARIANT_HEADER_PART_IVOP;
964                            break;
965                    case 'p':
966                    case 'P':
967                    case 's':
968                    case 'S':
969                            s->type = XVID_TYPE_PVOP;
970                            s->invariant /= INVARIANT_HEADER_PART_PVOP;
971                            break;
972                    case 'b':
973                    case 'B':
974                            s->type = XVID_TYPE_BVOP;
975                            s->invariant /= INVARIANT_HEADER_PART_BVOP;
976                            break;
977                    default:
978                            /* Same as before, fail silently */
979                            continue;
980                    }
981    
982                    /* Ok it seems it's been processed correctly */
983                    processed_entries++;
984            }
985    
986            /* Close the file */
987            fclose(f);
988    
989            return(0);
990    }
991    
992    /* pre-process the statistics data
993     * - for each type, count, tot_length, min_length, max_length
994     * - set keyframes_locations, tot_prescaled */
995    static void
996    first_pass_stats_prepare_data(rc_2pass2_t * rc)
997    {
998            int i,j;
999    
1000            /* *rc fields initialization
1001             * NB: INT_MAX and INT_MIN are used in order to be immediately replaced
1002             *     with real values of the 1pass */
1003            for (i=0; i<3; i++) {
1004                    rc->count[i]=0;
1005                    rc->tot_length[i] = 0;
1006                    rc->tot_invariant[i] = 0;
1007                    rc->min_length[i] = INT_MAX;
1008            }
1009    
1010            rc->max_length = INT_MIN;
1011            rc->tot_weighted = 0;
1012    
1013            /* Loop through all frames and find/compute all the stuff this function
1014             * is supposed to do */
1015            for (i=j=0; i<rc->num_frames; i++) {
1016                    twopass_stat_t * s = &rc->stats[i];
1017    
1018                    rc->count[s->type-1]++;
1019                    rc->tot_length[s->type-1] += s->length;
1020                    rc->tot_invariant[s->type-1] += s->invariant;
1021                    if (s->zone_mode != XVID_ZONE_QUANT)
1022                            rc->tot_weighted += (int)(s->weight*(s->length - s->invariant));
1023    
1024                    if (s->length < rc->min_length[s->type-1]) {
1025                            rc->min_length[s->type-1] = s->length;
1026                    }
1027    
1028                    if (s->length > rc->max_length) {
1029                            rc->max_length = s->length;
1030                    }
1031    
1032                    if (s->type == XVID_TYPE_IVOP) {
1033                            rc->keyframe_locations[j] = i;
1034                            j++;
1035                    }
1036            }
1037    
1038            /* NB:
1039             * The "per sequence" overflow system considers a natural sequence to be
1040             * formed by all frames between two iframes, so if we want to make sure
1041             * the system does not go nuts during last sequence, we force the last
1042             * frame to appear in the keyframe locations array. */
1043            rc->keyframe_locations[j] = i;
1044    
1045            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Min 1st pass IFrame length: %d\n", rc->min_length[0]);
1046            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Min 1st pass PFrame length: %d\n", rc->min_length[1]);
1047            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Min 1st pass BFrame length: %d\n", rc->min_length[2]);
1048    }
1049    
1050    /* calculate zone weight "center" */
1051    static void
1052    zone_process(rc_2pass2_t *rc, const xvid_plg_create_t * create)
1053    {
1054            int i,j;
1055            int n = 0;
1056    
1057            rc->tot_quant = 0;
1058            rc->tot_quant_invariant = 0;
1059    
1060            if (create->num_zones == 0) {
1061                    for (j = 0; j < rc->num_frames; j++) {
1062                            rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
1063                            rc->stats[j].weight = 1.0;
1064                    }
1065                    n += rc->num_frames;
1066            }
1067    
1068    
1069            for(i=0; i < create->num_zones; i++) {
1070    
1071                    int next = (i+1<create->num_zones) ? create->zones[i+1].frame : rc->num_frames;
1072    
1073                    /* Zero weight make no sense */
1074                    if (create->zones[i].increment == 0) create->zones[i].increment = 1;
1075                    /* And obviously an undetermined infinite makes even less sense */
1076                    if (create->zones[i].base == 0) create->zones[i].base = 1;
1077    
1078                    if (i==0 && create->zones[i].frame > 0) {
1079                            for (j = 0; j < create->zones[i].frame && j < rc->num_frames; j++) {
1080                                    rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
1081                                    rc->stats[j].weight = 1.0;
1082                            }
1083                            n += create->zones[i].frame;
1084                    }
1085    
1086                    if (create->zones[i].mode == XVID_ZONE_WEIGHT) {
1087                            for (j = create->zones[i].frame; j < next && j < rc->num_frames; j++ ) {
1088                                    rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
1089                                    rc->stats[j].weight = (double)create->zones[i].increment / (double)create->zones[i].base;
1090                            }
1091                            next -= create->zones[i].frame;
1092                            n += next;
1093                    } else{  /* XVID_ZONE_QUANT */
1094                            for (j = create->zones[i].frame; j < next && j < rc->num_frames; j++ ) {
1095                                    rc->stats[j].zone_mode = XVID_ZONE_QUANT;
1096                                    rc->stats[j].weight = (double)create->zones[i].increment / (double)create->zones[i].base;
1097                                    rc->tot_quant += rc->stats[j].length;
1098                                    rc->tot_quant_invariant += rc->stats[j].invariant;
1099                            }
1100                    }
1101            }
1102    }
1103    
1104    
1105    /* scale the curve */
1106    static void
1107    first_pass_scale_curve_internal(rc_2pass2_t *rc)
1108    {
1109            int64_t target;
1110            int64_t total_invariant;
1111            double scaler;
1112            int i, num_MBs;
1113    
1114            /* We only scale texture data ! */
1115            total_invariant  = rc->tot_invariant[XVID_TYPE_IVOP-1];
1116            total_invariant += rc->tot_invariant[XVID_TYPE_PVOP-1];
1117            total_invariant += rc->tot_invariant[XVID_TYPE_BVOP-1];
1118            /* don't forget to substract header bytes used in quant zones, otherwise we
1119             * counting them twice */
1120            total_invariant -= rc->tot_quant_invariant;
1121    
1122            /* We remove the bytes used by the fixed quantizer zones during first pass
1123             * with the same quants, so we know very precisely how much that
1124             * represents */
1125            target  = rc->target;
1126            target -= rc->tot_quant;
1127    
1128            /* Let's compute a linear scaler in order to perform curve scaling */
1129            scaler = (double)(target - total_invariant) / (double)(rc->tot_weighted);
1130    
1131    #ifdef SMART_OVERFLOW_SETTING
1132            if (scaler > 0.9) {
1133                    rc->param.max_overflow_degradation *= 5;
1134                    rc->param.max_overflow_improvement *= 5;
1135                    rc->param.overflow_control_strength *= 3;
1136            } else if (scaler > 0.6) {
1137                    rc->param.max_overflow_degradation *= 2;
1138                    rc->param.max_overflow_improvement *= 2;
1139                    rc->param.overflow_control_strength *= 2;
1140            } else {
1141                    rc->min_quant = 2;
1142            }
1143    #endif
1144    
1145            /* Compute min frame lengths (for each frame type) according to the number
1146             * of MBs. We sum all block type counters of frame 0, this gives us the
1147             * number of MBs.
1148             *
1149             * We compare these hardcoded values with observed values in first pass
1150             * (determined in pre_process0).Then we keep the real minimum. */
1151    
1152            /* Number of MBs */
1153            num_MBs  = rc->stats[0].blks[0];
1154            num_MBs += rc->stats[0].blks[1];
1155            num_MBs += rc->stats[0].blks[2];
1156    
1157            /* Minimum for I frames */
1158            if(rc->min_length[XVID_TYPE_IVOP-1] > ((num_MBs*22) + 240) / 8)
1159                    rc->min_length[XVID_TYPE_IVOP-1] = ((num_MBs*22) + 240) / 8;
1160    
1161            /* Minimum for P/S frames */
1162            if(rc->min_length[XVID_TYPE_PVOP-1] > ((num_MBs) + 88)  / 8)
1163                    rc->min_length[XVID_TYPE_PVOP-1] = ((num_MBs) + 88)  / 8;
1164    
1165            /* Minimum for B frames */
1166            if(rc->min_length[XVID_TYPE_BVOP-1] > 8)
1167                    rc->min_length[XVID_TYPE_BVOP-1] = 8;
1168    
1169            /* Perform an initial scale pass.
1170             *
1171             * If a frame size is scaled underneath our hardcoded minimums, then we
1172             * force the frame size to the minimum, and deduct the original & scaled
1173             * frame length from the original and target total lengths */
1174            for (i=0; i<rc->num_frames; i++) {
1175                    twopass_stat_t * s = &rc->stats[i];
1176                    int len;
1177    
1178                    /* No need to scale frame length for which a specific quantizer is
1179                     * specified thanks to zones */
1180                    if (s->zone_mode == XVID_ZONE_QUANT) {
1181                            s->scaled_length = s->length;
1182                            continue;
1183                    }
1184    
1185                    /* Compute the scaled length -- only non invariant data length is scaled */
1186                    len = s->invariant + (int)((double)(s->length-s->invariant) * scaler * s->weight);
1187    
1188                    /* Compare with the computed minimum */
1189                    if (len < rc->min_length[s->type-1]) {
1190                            /* This is a 'forced size' frame, set its frame size to the
1191                             * computed minimum */
1192                            s->scaled_length = rc->min_length[s->type-1];
1193    
1194                            /* Remove both scaled and original size from their respective
1195                             * total counters, as we prepare a second pass for 'regular'
1196                             * frames */
1197                            target -= s->scaled_length;
1198                    } else {
1199                            /* Do nothing for now, we'll scale this later */
1200                            s->scaled_length = 0;
1201                    }
1202            }
1203    
1204            /* The first pass on data substracted all 'forced size' frames from the
1205             * total counters. Now, it's possible to scale the 'regular' frames. */
1206    
1207            /* Scaling factor for 'regular' frames */
1208            scaler = (double)(target - total_invariant) / (double)(rc->tot_weighted);
1209    
1210            /* Do another pass with the new scaler */
1211            for (i=0; i<rc->num_frames; i++) {
1212                    twopass_stat_t * s = &rc->stats[i];
1213    
1214                    /* Ignore frame with forced frame sizes */
1215                    if (s->scaled_length == 0)
1216                            s->scaled_length = s->invariant + (int)((double)(s->length-s->invariant) * scaler * s->weight);
1217            }
1218    
1219            /* Job done */
1220            return;
1221    }
1222    
1223    /* Apply all user settings to the scaled curve
1224     * This implies:
1225     *   keyframe boosting
1226     *   high/low compression */
1227    static void
1228    scaled_curve_apply_advanced_parameters(rc_2pass2_t * rc)
1229    {
1230            int i;
1231            int64_t ivop_boost_total;
1232    
1233            /* Reset the rate controller (per frame type) total byte counters */
1234            for (i=0; i<3; i++) rc->tot_scaled_length[i] = 0;
1235    
1236            /* Compute total bytes for each frame type */
1237            for (i=0; i<rc->num_frames;i++) {
1238                    twopass_stat_t *s = &rc->stats[i];
1239                    rc->tot_scaled_length[s->type-1] += s->scaled_length;
1240            }
1241    
1242            /* First we compute the total amount of bits needed, as being described by
1243             * the scaled distribution. During this pass over the complete stats data,
1244             * we see how much bits two user settings will get/give from/to p&b frames:
1245             *  - keyframe boosting
1246             *  - keyframe distance penalty */
1247            rc->KF_idx = 0;
1248            ivop_boost_total = 0;
1249            for (i=0; i<rc->num_frames; i++) {
1250                    twopass_stat_t * s = &rc->stats[i];
1251    
1252                    /* Some more work is needed for I frames */
1253                    if (s->type == XVID_TYPE_IVOP) {
1254                            int ivop_boost;
1255    
1256                            /* Accumulate bytes needed for keyframe boosting */
1257                            ivop_boost = s->scaled_length*rc->param.keyframe_boost/100;
1258    
1259    #if 0 /* ToDo: decide how to apply kfthresholding */
1260    #endif
1261                            /* If the frame size drops under the minimum length, then cap ivop_boost */
1262                            if (ivop_boost + s->scaled_length < rc->min_length[XVID_TYPE_IVOP-1])
1263                                    ivop_boost = rc->min_length[XVID_TYPE_IVOP-1] - s->scaled_length;
1264    
1265                            /* Accumulate the ivop boost */
1266                            ivop_boost_total += ivop_boost;
1267    
1268                            /* Don't forget to update the keyframe index */
1269                            rc->KF_idx++;
1270                    }
1271            }
1272    
1273            /* Initialize the IBoost tax ratio for P/S/B frames
1274             *
1275             * This ratio has to be applied to p/b/s frames in order to reserve
1276             * additional bits for keyframes (keyframe boosting) or if too much
1277             * keyframe distance is applied, bits retrieved from the keyframes.
1278             *
1279             * ie pb_length *= rc->pb_iboost_tax_ratio;
1280             *
1281             *    gives the ideal length of a p/b frame */
1282    
1283            /* Compute the total length of p/b/s frames (temporary storage into
1284             * movie_curve) */
1285            rc->pb_iboost_tax_ratio  = (double)rc->tot_scaled_length[XVID_TYPE_PVOP-1];
1286            rc->pb_iboost_tax_ratio += (double)rc->tot_scaled_length[XVID_TYPE_BVOP-1];
1287    
1288            /* Compute the ratio described above
1289             *     taxed_total = sum(0, n, tax*scaled_length)
1290             * <=> taxed_total = tax.sum(0, n, scaled_length)
1291             * <=> tax = taxed_total / original_total */
1292            rc->pb_iboost_tax_ratio =
1293                    (rc->pb_iboost_tax_ratio - ivop_boost_total) /
1294                    rc->pb_iboost_tax_ratio;
1295    
1296            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- IFrame boost tax ratio:%.2f\n",
1297                            rc->pb_iboost_tax_ratio);
1298    
1299            /* Compute the average size of frames per frame type */
1300            for(i=0; i<3; i++) {
1301                    /* Special case for missing type or weird case */
1302                    if (rc->count[i] == 0 || rc->pb_iboost_tax_ratio == 0) {
1303                            rc->avg_length[i] = 1;
1304                    } else {
1305                            rc->avg_length[i] = rc->tot_scaled_length[i];
1306    
1307                            if (i == (XVID_TYPE_IVOP-1)) {
1308                                    /* I Frames total has to be added the boost total */
1309                                    rc->avg_length[i] += ivop_boost_total;
1310                            } else {
1311                                    /* P/B frames has to taxed */
1312                                    rc->avg_length[i] *= rc->pb_iboost_tax_ratio;
1313                            }
1314    
1315                            /* Finally compute the average frame size */
1316                            rc->avg_length[i] /= (double)rc->count[i];
1317                    }
1318            }
1319    
1320            /* Assymetric curve compression */
1321            if (rc->param.curve_compression_high || rc->param.curve_compression_low) {
1322                    double symetric_total;
1323                    double assymetric_delta_total;
1324    
1325                    /* Like I frame boosting, assymetric curve compression modifies the total
1326                     * amount of needed bits, we must compute the ratio so we can prescale
1327                     lengths */
1328                    symetric_total = 0;
1329                    assymetric_delta_total = 0;
1330                    for (i=0; i<rc->num_frames; i++) {
1331                            double assymetric_delta;
1332                            double dbytes;
1333                            twopass_stat_t * s = &rc->stats[i];
1334    
1335                            /* I Frames are not concerned by assymetric scaling */
1336                            if (s->type == XVID_TYPE_IVOP)
1337                                    continue;
1338    
1339                            /* During the real run, we would have to apply the iboost tax */
1340                            dbytes = s->scaled_length * rc->pb_iboost_tax_ratio;
1341    
1342                            /* Update the symmetric curve compression total */
1343                            symetric_total += dbytes;
1344    
1345                            /* Apply assymetric curve compression */
1346                            if (dbytes > rc->avg_length[s->type-1])
1347                                    assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * (double)rc->param.curve_compression_high / 100.0f;
1348                            else
1349                                    assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * (double)rc->param.curve_compression_low  / 100.0f;
1350    
1351                            /* Cap to the minimum frame size if needed */
1352                            if (dbytes + assymetric_delta < rc->min_length[s->type-1])
1353                                    assymetric_delta = rc->min_length[s->type-1] - dbytes;
1354    
1355                            /* Accumulate after assymetric curve compression */
1356                            assymetric_delta_total += assymetric_delta;
1357                    }
1358    
1359                    /* Compute the tax that all p/b frames have to pay in order to respect the
1360                     * bit distribution changes that the assymetric compression curve imposes
1361                     * We want assymetric_total = sum(0, n-1, tax.scaled_length)
1362                     *      ie assymetric_total = ratio.sum(0, n-1, scaled_length)
1363                     *         ratio = assymetric_total / symmetric_total */
1364                    rc->assymetric_tax_ratio = ((double)symetric_total - (double)assymetric_delta_total) / (double)symetric_total;
1365            } else {
1366                    rc->assymetric_tax_ratio = 1.0f;
1367            }
1368    
1369            DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Assymetric tax ratio:%.2f\n", rc->assymetric_tax_ratio);
1370    
1371            /* Last bits that need to be reset */
1372            rc->overflow = 0;
1373            rc->KFoverflow = 0;
1374            rc->KFoverflow_partial = 0;
1375            rc->KF_idx = 0;
1376            rc->desired_total = 0;
1377            rc->real_total = 0;
1378    
1379            /* Job done */
1380            return;
1381    }
1382    
1383    /*****************************************************************************
1384     * Still more low level stuff (nothing to do with stats treatment)
1385     ****************************************************************************/
1386    
1387    /* This function returns an allocated string containing a complete line read
1388     * from the file starting at the current position */
1389    static char *
1390    readline(FILE *f)
1391    {
1392            char *buffer = NULL;
1393            int buffer_size = 0;
1394            int pos = 0;
1395    
1396            do {
1397                    int c;
1398    
1399                    /* Read a character from the stream */
1400                    c = fgetc(f);
1401    
1402                    /* Is that EOF or new line ? */
1403                    if(c == EOF || c == '\n')
1404                            break;
1405    
1406                    /* Do we have to update buffer ? */
1407                    if(pos >= buffer_size - 1) {
1408                            buffer_size += BUF_SZ;
1409                            buffer = (char*)realloc(buffer, buffer_size);
1410                            if (buffer == NULL)
1411                                    return(NULL);
1412                    }
1413    
1414                    buffer[pos] = c;
1415                    pos++;
1416            } while(1);
1417    
1418            /* Read \n or EOF */
1419            if (buffer == NULL) {
1420                    /* EOF, so we reached the end of the file, return NULL */
1421                    if(feof(f))
1422                            return(NULL);
1423    
1424                    /* Just an empty line with just a newline, allocate a 1 byte buffer to
1425                     * store a zero length string */
1426                    buffer = (char*)malloc(1);
1427                    if(buffer == NULL)
1428                            return(NULL);
1429            }
1430    
1431            /* Zero terminated string */
1432            buffer[pos] = '\0';
1433    
1434            return(buffer);
1435    }
1436    
1437    /* This function returns a pointer to the first non space char in the given
1438     * string */
1439    static char *
1440    skipspaces(char *string)
1441    {
1442            const char spaces[] =
1443                    {
1444                            ' ','\t','\0'
1445                    };
1446            const char *spacechar = spaces;
1447    
1448            if (string == NULL) return(NULL);
1449    
1450            while (*string != '\0') {
1451                    /* Test against space chars */
1452                    while (*spacechar != '\0') {
1453                            if (*string == *spacechar) {
1454                                    string++;
1455                                    spacechar = spaces;
1456                                    break;
1457                            }
1458                            spacechar++;
1459                    }
1460    
1461                    /* No space char */
1462                    if (*spacechar == '\0') return(string);
1463            }
1464    
1465            return(string);
1466    }
1467    
1468    /* This function returns a boolean that tells if the string is only a
1469     * comment */
1470    static int
1471    iscomment(char *string)
1472    {
1473            const char comments[] =
1474                    {
1475                            '#',';', '%', '\0'
1476                    };
1477            const char *cmtchar = comments;
1478            int iscomment = 0;
1479    
1480            if (string == NULL) return(1);
1481    
1482            string = skipspaces(string);
1483    
1484            while(*cmtchar != '\0') {
1485                    if(*string == *cmtchar) {
1486                            iscomment = 1;
1487                            break;
1488                    }
1489                    cmtchar++;
1490            }
1491    
1492            return(iscomment);
1493    }
1494    
1495    #if 0
1496    static void
1497    stats_print(rc_2pass2_t * rc)
1498    {
1499            int i;
1500            const char frame_type[4] = { 'i', 'p', 'b', 's'};
1501    
1502            for (i=0; i<rc->num_frames; i++) {
1503                    twopass_stat_t *s = &rc->stats[i];
1504                    DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- frame:%d type:%c quant:%d stats:%d scaled:%d desired:%d actual:%d overflow(%c):%.2f\n",
1505                                    i, frame_type[s->type-1], -1, s->length, s->scaled_length,
1506                                    s->desired_length, -1, frame_type[s->type-1], -1.0f);
1507            }
1508    }
1509    #endif

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