ratecontrol.c

H.264 source codes

/***************************************************-*- coding: iso-8859-1 -*-
 * ratecontrol.c: h264 encoder library (Rate Control)
 *****************************************************************************
 * Copyright (C) 2005 x264 project
 * $Id: ratecontrol.c,v 1.1 2004/06/03 19:27:08 fenrir Exp $
 *
 * Authors: Loren Merritt <[e-mail]>
 *          Michael Niedermayer <[e-mail]>
 *          M錸s Rullg錼d <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/

#define _ISOC99_SOURCE
#undef NDEBUG // always check asserts, the speed effect is far too small to disable them
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include <assert.h>

#include "common/common.h"
#include "common/cpu.h"
#include "common/macroblock.h"
#include "ratecontrol.h"

#if defined(SYS_FREEBSD) || defined(SYS_BEOS)
#define exp2f(x) powf( 2, (x) )
#endif
#ifdef _MSC_VER
#define exp2f(x) pow( 2, (x) )
#define sqrtf sqrt
#endif
#ifdef WIN32 // POSIX says that rename() removes the destination, but win32 doesn't.
#define rename(src,dst) (unlink(dst), rename(src,dst))
#endif

typedef struct
{
    int pict_type;
    int kept_as_ref;
    float qscale;
    int mv_bits;
    int i_tex_bits;
    int p_tex_bits;
    int misc_bits;
    uint64_t expected_bits;
    float new_qscale;
    int new_qp;
    int i_count;
    int p_count;
    int s_count;
    float blurred_complexity;
} ratecontrol_entry_t;

typedef struct
{
    double coeff;
    double count;
    double decay;
} predictor_t;

struct x264_ratecontrol_t
{
    /* constants */
    int b_abr;
    int b_2pass;
    double fps;
    double bitrate;
    double rate_tolerance;
    int nmb;                    /* number of macroblocks in a frame */
    int qp_constant[5];

    /* current frame */
    ratecontrol_entry_t *rce;
    int qp;                     /* qp for current frame */
    float qpa;                  /* average of macroblocks' qp (same as qp if no adaptive quant) */
    int slice_type;
    int qp_force;

    /* VBV stuff */
    double buffer_size;
    double buffer_fill;
    double buffer_rate;         /* # of bits added to buffer_fill after each frame */
    predictor_t pred[5];        /* predict frame size from satd */

    /* ABR stuff */
    int    last_satd;
    double last_rceq;
    double cplxr_sum;           /* sum of bits*qscale/rceq */
    double expected_bits_sum;   /* sum of qscale2bits after rceq, ratefactor, and overflow */
    double wanted_bits_window;  /* target bitrate * window */
    double cbr_decay;
    double short_term_cplxsum;
    double short_term_cplxcount;

    /* 2pass stuff */
    FILE *p_stat_file_out;
    char *psz_stat_file_tmpname;

    int num_entries;            /* number of ratecontrol_entry_ts */
    ratecontrol_entry_t *entry; /* FIXME: copy needed data and free this once init is done */
    double last_qscale;
    double last_qscale_for[5];  /* last qscale for a specific pict type, used for max_diff & ipb factor stuff  */
    int last_non_b_pict_type;
    double accum_p_qp;          /* for determining I-frame quant */
    double accum_p_norm;
    double last_accum_p_norm;
    double lmin[5];             /* min qscale by frame type */
    double lmax[5];
    double lstep;               /* max change (multiply) in qscale per frame */
    double i_cplx_sum[5];       /* estimated total texture bits in intra MBs at qscale=1 */
    double p_cplx_sum[5];
    double mv_bits_sum[5];
    int frame_count[5];         /* number of frames of each type */
};


static int init_pass2(x264_t *);
static float rate_estimate_qscale( x264_t *h, int pict_type );
static void update_vbv( x264_t *h, int bits );
int  x264_rc_analyse_slice( x264_t *h );

/* Terminology:
 * qp = h.264's quantizer
 * qscale = linearized quantizer = Lagrange multiplier
 */
static inline double qp2qscale(double qp)
{
    return 0.85 * pow(2.0, ( qp - 12.0 ) / 6.0);
}
static inline double qscale2qp(double qscale)
{
    return 12.0 + 6.0 * log(qscale/0.85) / log(2.0);
}

/* Texture bitrate is not quite inversely proportional to qscale,
 * probably due the the changing number of SKIP blocks.
 * MV bits level off at about qp<=12, because the lambda used
 * for motion estimation is constant there. */
static inline double qscale2bits(ratecontrol_entry_t *rce, double qscale)
{
    if(qscale<0.1)
        qscale = 0.1;
    return (rce->i_tex_bits + rce->p_tex_bits + .1) * pow( rce->qscale / qscale, 1.1 )
           + rce->mv_bits * pow( X264_MAX(rce->qscale, 12) / X264_MAX(qscale, 12), 0.5 );
}

/* There is no analytical inverse to the above formula. */
#if 0
static inline double bits2qscale(ratecontrol_entry_t *rce, double bits)
{
    if(bits<1.0)
        bits = 1.0;
    return (rce->i_tex_bits + rce->p_tex_bits + rce->mv_bits + .1) * rce->qscale / bits;
}
#endif


int x264_ratecontrol_new( x264_t *h )
{
    x264_ratecontrol_t *rc;
    int i;

    x264_cpu_restore( h->param.cpu );

    h->rc = rc = x264_malloc( sizeof( x264_ratecontrol_t ) );
    memset(rc, 0, sizeof(*rc));

    rc->b_abr = h->param.rc.b_cbr && !h->param.rc.b_stat_read;
    rc->b_2pass = h->param.rc.b_cbr && h->param.rc.b_stat_read;
    h->mb.b_variable_qp = 0;
    
    /* FIXME: use integers */
    if(h->param.i_fps_num > 0 && h->param.i_fps_den > 0)
        rc->fps = (float) h->param.i_fps_num / h->param.i_fps_den;
    else
        rc->fps = 25.0;

    rc->bitrate = h->param.rc.i_bitrate * 1000;
    rc->rate_tolerance = h->param.rc.f_rate_tolerance;
    rc->nmb = h->mb.i_mb_count;
    rc->last_non_b_pict_type = -1;
    rc->cbr_decay = 1.0;

    if( h->param.rc.i_vbv_max_bitrate < h->param.rc.i_bitrate &&
        h->param.rc.i_vbv_max_bitrate > 0)
        x264_log(h, X264_LOG_ERROR, "max bitrate less than average bitrate, ignored.\n");
    else if( h->param.rc.i_vbv_max_bitrate > 0 &&
             h->param.rc.i_vbv_buffer_size > 0 )
    {
        if( h->param.rc.i_vbv_buffer_size < 10 * h->param.rc.i_vbv_max_bitrate / rc->fps ) {
            h->param.rc.i_vbv_buffer_size = 10 * h->param.rc.i_vbv_max_bitrate / rc->fps;
            x264_log( h, X264_LOG_ERROR, "VBV buffer size too small, using %d kbit\n",
                      h->param.rc.i_vbv_buffer_size );
        }
        rc->buffer_rate = h->param.rc.i_vbv_max_bitrate * 1000 / rc->fps;
        rc->buffer_size = h->param.rc.i_vbv_buffer_size * 1000;
        rc->buffer_fill = rc->buffer_size * h->param.rc.f_vbv_buffer_init;
        rc->cbr_decay = 1.0 - rc->buffer_rate / rc->buffer_size
                      * 0.5 * X264_MAX(0, 1.5 - rc->buffer_rate * rc->fps / rc->bitrate);
    }
    else if( h->param.rc.i_vbv_max_bitrate || h->param.rc.i_vbv_buffer_size )
        x264_log(h, X264_LOG_ERROR, "VBV maxrate or buffer size specified, but not both.\n");

    if( rc->b_abr )
    {
        /* FIXME shouldn't need to arbitrarily specify a QP,
         * but this is more robust than BPP measures */
#define ABR_INIT_QP 24
        rc->accum_p_norm = .01;
        rc->accum_p_qp = ABR_INIT_QP * rc->accum_p_norm;
        rc->cplxr_sum = .01;
        rc->wanted_bits_window = .01;
    }

    rc->qp_constant[SLICE_TYPE_P] = h->param.rc.i_qp_constant;
    rc->qp_constant[SLICE_TYPE_I] = x264_clip3( (int)( qscale2qp( qp2qscale( h->param.rc.i_qp_constant ) / fabs( h->param.rc.f_ip_factor )) + 0.5 ), 0, 51 );
    rc->qp_constant[SLICE_TYPE_B] = x264_clip3( (int)( qscale2qp( qp2qscale( h->param.rc.i_qp_constant ) * fabs( h->param.rc.f_pb_factor )) + 0.5 ), 0, 51 );

    rc->lstep = exp2f(h->param.rc.i_qp_step / 6.0);
    rc->last_qscale = qp2qscale(26);
    for( i = 0; i < 5; i++ )
    {
        rc->last_qscale_for[i] = qp2qscale(26);
        rc->lmin[i] = qp2qscale( h->param.rc.i_qp_min );
        rc->lmax[i] = qp2qscale( h->param.rc.i_qp_max );
        rc->pred[i].coeff= 2.0;
        rc->pred[i].count= 1.0;
        rc->pred[i].decay= 0.5;
    }
#if 0 // FIXME: do we want to assign lmin/lmax based on ip_factor, or leave them all the same?
    rc->lmin[SLICE_TYPE_I] /= fabs(h->param.f_ip_factor);
    rc->lmax[SLICE_TYPE_I] /= fabs(h->param.f_ip_factor);
    rc->lmin[SLICE_TYPE_B] *= fabs(h->param.f_pb_factor);
    rc->lmax[SLICE_TYPE_B] *= fabs(h->param.f_pb_factor);
#endif

    /* Load stat file and init 2pass algo */
    if( h->param.rc.b_stat_read )
    {
        int stats_size;
        char *p, *stats_in;
        FILE *stats_file;

        /* read 1st pass stats */
        assert( h->param.rc.psz_stat_in );
        stats_file = fopen( h->param.rc.psz_stat_in, "rb");
        if(!stats_file)
        {
            x264_log(h, X264_LOG_ERROR, "ratecontrol_init: can't open stats file\n");
            return -1;
        }
        // FIXME: error checking
        fseek(stats_file, 0, SEEK_END);
        stats_size = ftell(stats_file);
        fseek(stats_file, 0, SEEK_SET);
        stats_in = x264_malloc(stats_size+10);
        fread(stats_in, 1, stats_size, stats_file);
        fclose(stats_file);

        /* find number of pics */
        p = stats_in;
        for(i=-1; p; i++)
            p = strchr(p+1, ';');
        if(i==0)
        {
            x264_log(h, X264_LOG_ERROR, "empty stats file\n");
            return -1;
        }
        i += h->param.i_bframe;
        rc->entry = (ratecontrol_entry_t*) x264_malloc(i*sizeof(ratecontrol_entry_t));
        memset(rc->entry, 0, i*sizeof(ratecontrol_entry_t));
        /* FIXME: num_entries is sometimes treated as number of frames in the video */
        rc->num_entries= i;

        /* init all to skipped p frames */
        for(i=0; i<rc->num_entries; i++){
            ratecontrol_entry_t *rce = &rc->entry[i];
            rce->pict_type = SLICE_TYPE_P;
            rce->qscale = rce->new_qscale = qp2qscale(20);
            rce->misc_bits = rc->nmb + 10;
            rce->new_qp = 0;
        }

        /* read stats */
        p = stats_in;
        for(i=0; i < rc->num_entries - h->param.i_bframe; i++){
            ratecontrol_entry_t *rce;
            int frame_number;
            char pict_type;
            int e;
            char *next;
            float qp;

            next= strchr(p, ';');
            if(next){
                (*next)=0; //sscanf is unbelievably slow on looong strings
                next++;
            }
            e = sscanf(p, " in:%d ", &frame_number);

            if(frame_number < 0 || frame_number >= rc->num_entries)
            {
                x264_log(h, X264_LOG_ERROR, "bad frame number (%d) at stats line %d\n", frame_number, i);
                return -1;
            }
            rce = &rc->entry[frame_number];

            e += sscanf(p, " in:%*d out:%*d type:%c q:%f itex:%d ptex:%d mv:%d misc:%d imb:%d pmb:%d smb:%d",
                   &pict_type, &qp, &rce->i_tex_bits, &rce->p_tex_bits,
                   &rce->mv_bits, &rce->misc_bits, &rce->i_count, &rce->p_count, &rce->s_count);

            switch(pict_type){
                case 'I': rce->kept_as_ref = 1;
                case 'i': rce->pict_type = SLICE_TYPE_I; break;
                case 'P': rce->pict_type = SLICE_TYPE_P; break;
                case 'B': rce->kept_as_ref = 1;
                case 'b': rce->pict_type = SLICE_TYPE_B; break;
                default:  e = -1; break;
            }
            if(e != 10){
                x264_log(h, X264_LOG_ERROR, "statistics are damaged at line %d, parser out=%d\n", i, e);
                return -1;
            }
            rce->qscale = qp2qscale(qp);
            p = next;
        }

        x264_free(stats_in);

        if(h->param.rc.b_cbr)
        {
            if(init_pass2(h) < 0) return -1;
        } /* else we're using constant quant, so no need to run the bitrate allocation */
    }

    /* Open output file */
    /* If input and output files are the same, output to a temp file
     * and move it to the real name only when it's complete */
    if( h->param.rc.b_stat_write )