ratecontrol.c 52.6 KB
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/***************************************************-*- coding: iso-8859-1 -*-
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 * ratecontrol.c: h264 encoder library (Rate Control)
 *****************************************************************************
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 * Copyright (C) 2005 x264 project
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 * $Id: ratecontrol.c,v 1.1 2004/06/03 19:27:08 fenrir Exp $
 *
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 * Authors: Loren Merritt <lorenm@u.washington.edu>
 *          Michael Niedermayer <michaelni@gmx.at>
 *          Mns Rullgrd <mru@mru.ath.cx>
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 *
 * 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.
 *****************************************************************************/

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

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#if defined(SYS_FREEBSD) || defined(SYS_BEOS) || defined(SYS_NETBSD)
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#define exp2f(x) powf( 2, (x) )
#endif
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#if defined(SYS_MACOSX)
#define exp2f(x) (float)pow( 2, (x) )
#define sqrtf sqrt
#endif
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#if defined(_MSC_VER)
#define isfinite _finite
#endif
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#if defined(_MSC_VER) || defined(SYS_SunOS)
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#define exp2f(x) pow( 2, (x) )
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#define sqrtf sqrt
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#endif
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#ifdef WIN32 // POSIX says that rename() removes the destination, but win32 doesn't.
#define rename(src,dst) (unlink(dst), rename(src,dst))
#endif
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typedef struct
{
    int pict_type;
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    int kept_as_ref;
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    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;
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    float blurred_complexity;
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    char direct_mode;
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} ratecontrol_entry_t;

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

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struct x264_ratecontrol_t
{
    /* constants */
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    int b_abr;
    int b_2pass;
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    int b_vbv;
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    double fps;
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    double bitrate;
    double rate_tolerance;
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    int nmb;                    /* number of macroblocks in a frame */
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    int qp_constant[5];
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    /* current frame */
    ratecontrol_entry_t *rce;
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    int qp;                     /* qp for current frame */
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    int qpm;                    /* qp for current macroblock */
    float qpa;                  /* average of macroblocks' qp */
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    int slice_type;
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    int qp_force;
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    /* 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;
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    double rate_factor_constant;
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    double ip_offset;
    double pb_offset;
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    /* 2pass stuff */
    FILE *p_stat_file_out;
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    char *psz_stat_file_tmpname;
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    int num_entries;            /* number of ratecontrol_entry_ts */
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    ratecontrol_entry_t *entry; /* FIXME: copy needed data and free this once init is done */
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    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;
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    double accum_p_qp;          /* for determining I-frame quant */
    double accum_p_norm;
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    double last_accum_p_norm;
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    double lmin[5];             /* min qscale by frame type */
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    double lmax[5];
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    double lstep;               /* max change (multiply) in qscale per frame */
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    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 */
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    /* MBRC stuff */
    double frame_size_planned;
    int first_row, last_row;    /* region of the frame to be encoded by this thread */
    predictor_t *row_pred;
    predictor_t row_preds[5];
    predictor_t pred_b_from_p;  /* predict B-frame size from P-frame satd */
    int bframes;                /* # consecutive B-frames before this P-frame */
    int bframe_bits;            /* total cost of those frames */

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    int i_zones;
    x264_zone_t *zones;
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};
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static int parse_zones( x264_t *h );
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static int init_pass2(x264_t *);
static float rate_estimate_qscale( x264_t *h, int pict_type );
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static void update_vbv( x264_t *h, int bits );
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static double predict_size( predictor_t *p, double q, double var );
static void update_predictor( predictor_t *p, double q, double var, double bits );
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int  x264_rc_analyse_slice( x264_t *h );
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/* Terminology:
 * qp = h.264's quantizer
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 * qscale = linearized quantizer = Lagrange multiplier
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 */
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);
}

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/* 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. */
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static inline double qscale2bits(ratecontrol_entry_t *rce, double qscale)
{
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    if(qscale<0.1)
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        qscale = 0.1;
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    return (rce->i_tex_bits + rce->p_tex_bits + .1) * pow( rce->qscale / qscale, 1.1 )
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           + rce->mv_bits * pow( X264_MAX(rce->qscale, 12) / X264_MAX(qscale, 12), 0.5 )
           + rce->misc_bits;
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}


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int x264_ratecontrol_new( x264_t *h )
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{
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    x264_ratecontrol_t *rc;
    int i;
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    x264_cpu_restore( h->param.cpu );

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    h->rc = rc = x264_malloc( h->param.i_threads * sizeof(x264_ratecontrol_t) );
    memset( rc, 0, h->param.i_threads * sizeof(x264_ratecontrol_t) );
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    rc->b_abr = ( h->param.rc.b_cbr || h->param.rc.i_rf_constant ) && !h->param.rc.b_stat_read;
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    rc->b_2pass = h->param.rc.b_cbr && h->param.rc.b_stat_read;
    
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    /* 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;

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

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    if( h->param.rc.i_rf_constant && h->param.rc.b_stat_read )
    {
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        x264_log(h, X264_LOG_ERROR, "constant rate-factor is incompatible with 2pass.\n");
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        return -1;
    }
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    if( h->param.rc.i_vbv_buffer_size && !h->param.rc.b_cbr && !h->param.rc.i_rf_constant )
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        x264_log(h, X264_LOG_ERROR, "VBV is incompatible with constant QP.\n");
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    if( h->param.rc.i_vbv_buffer_size && h->param.rc.b_cbr
        && h->param.rc.i_vbv_max_bitrate == 0 )
    {
        x264_log( h, X264_LOG_DEBUG, "VBV maxrate unspecified, assuming CBR\n" );
        h->param.rc.i_vbv_max_bitrate = h->param.rc.i_bitrate;
    }
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    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 )
    {
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        if( h->param.rc.i_vbv_buffer_size < 3 * h->param.rc.i_vbv_max_bitrate / rc->fps ) {
            h->param.rc.i_vbv_buffer_size = 3 * h->param.rc.i_vbv_max_bitrate / rc->fps;
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            x264_log( h, X264_LOG_ERROR, "VBV buffer size too small, using %d kbit\n",
                      h->param.rc.i_vbv_buffer_size );
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        }
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        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);
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        rc->b_vbv = 1;
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    }
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    else if( h->param.rc.i_vbv_max_bitrate )
        x264_log(h, X264_LOG_ERROR, "VBV maxrate specified, but no bufsize.\n");
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    if(rc->rate_tolerance < 0.01) {
        x264_log(h, X264_LOG_ERROR, "bitrate tolerance too small, using .01\n");
        rc->rate_tolerance = 0.01;
    }
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    h->mb.b_variable_qp = rc->b_vbv;

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    if( rc->b_abr )
    {
        /* FIXME shouldn't need to arbitrarily specify a QP,
         * but this is more robust than BPP measures */
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#define ABR_INIT_QP ( h->param.rc.i_rf_constant > 0 ? h->param.rc.i_rf_constant : 24 )
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        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;
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    }

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    if( h->param.rc.i_rf_constant )
    {
        /* arbitrary rescaling to make CRF somewhat similar to QP */
        double base_cplx = h->mb.i_mb_count * (h->param.i_bframe ? 120 : 80);
        rc->rate_factor_constant = pow( base_cplx, 1 - h->param.rc.f_qcompress )
                                 / qp2qscale( h->param.rc.i_rf_constant );
    }

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    rc->ip_offset = 6.0 * log(h->param.rc.f_ip_factor) / log(2.0);
    rc->pb_offset = 6.0 * log(h->param.rc.f_pb_factor) / log(2.0);
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    rc->qp_constant[SLICE_TYPE_P] = h->param.rc.i_qp_constant;
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    rc->qp_constant[SLICE_TYPE_I] = x264_clip3( h->param.rc.i_qp_constant - rc->ip_offset + 0.5, 0, 51 );
    rc->qp_constant[SLICE_TYPE_B] = x264_clip3( h->param.rc.i_qp_constant + rc->pb_offset + 0.5, 0, 51 );
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    rc->lstep = exp2f(h->param.rc.i_qp_step / 6.0);
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    rc->last_qscale = qp2qscale(26);
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    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 );
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        rc->pred[i].coeff= 2.0;
        rc->pred[i].count= 1.0;
        rc->pred[i].decay= 0.5;
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        rc->row_preds[i].coeff= .25;
        rc->row_preds[i].count= 1.0;
        rc->row_preds[i].decay= 0.5;
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    }
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    rc->pred_b_from_p = rc->pred[0];
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    if( parse_zones( h ) < 0 )
        return -1;
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    /* Load stat file and init 2pass algo */
    if( h->param.rc.b_stat_read )
    {
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        char *p, *stats_in, *stats_buf;
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        /* read 1st pass stats */
        assert( h->param.rc.psz_stat_in );
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        stats_buf = stats_in = x264_slurp_file( h->param.rc.psz_stat_in );
        if( !stats_buf )
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        {
            x264_log(h, X264_LOG_ERROR, "ratecontrol_init: can't open stats file\n");
            return -1;
        }

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        /* check whether 1st pass options were compatible with current options */
        if( !strncmp( stats_buf, "#options:", 9 ) )
        {
            int i;
            char *opts = stats_buf;
            stats_in = strchr( stats_buf, '\n' );
            if( !stats_in )
                return -1;
            *stats_in = '\0';
            stats_in++;

            if( ( p = strstr( opts, "bframes=" ) ) && sscanf( p, "bframes=%d", &i )
                && h->param.i_bframe != i )
            {
                x264_log( h, X264_LOG_ERROR, "different number of B-frames than 1st pass (%d vs %d)\n",
                          h->param.i_bframe, i );
                return -1;
            }

            /* since B-adapt doesn't (yet) take into account B-pyramid,
             * the converse is not a problem */
            if( strstr( opts, "b_pyramid=1" ) && !h->param.b_bframe_pyramid )
                x264_log( h, X264_LOG_WARNING, "1st pass used B-pyramid, 2nd doesn't\n" );

            if( ( p = strstr( opts, "keyint=" ) ) && sscanf( p, "keyint=%d", &i )
                && h->param.i_keyint_max != i )
                x264_log( h, X264_LOG_WARNING, "different keyint than 1st pass (%d vs %d)\n",
                          h->param.i_keyint_max, i );

            if( strstr( opts, "qp=0" ) && h->param.rc.b_cbr )
                x264_log( h, X264_LOG_WARNING, "1st pass was lossless, bitrate prediction will be inaccurate\n" );
        }

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        /* find number of pics */
        p = stats_in;
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        for(i=-1; p; i++)
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            p = strchr(p+1, ';');
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        if(i==0)
        {
            x264_log(h, X264_LOG_ERROR, "empty stats file\n");
            return -1;
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        }
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        rc->num_entries = i;

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        if( h->param.i_frame_total < rc->num_entries && h->param.i_frame_total > 0 )
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        {
            x264_log( h, X264_LOG_WARNING, "2nd pass has fewer frames than 1st pass (%d vs %d)\n",
                      h->param.i_frame_total, rc->num_entries );
        }
        if( h->param.i_frame_total > rc->num_entries + h->param.i_bframe )
        {
            x264_log( h, X264_LOG_ERROR, "2nd pass has more frames than 1st pass (%d vs %d)\n",
                      h->param.i_frame_total, rc->num_entries );
            return -1;
        }

        /* FIXME: ugly padding because VfW drops delayed B-frames */
        rc->num_entries += h->param.i_bframe;

        rc->entry = (ratecontrol_entry_t*) x264_malloc(rc->num_entries * sizeof(ratecontrol_entry_t));
        memset(rc->entry, 0, rc->num_entries * sizeof(ratecontrol_entry_t));
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        /* init all to skipped p frames */
        for(i=0; i<rc->num_entries; i++){
            ratecontrol_entry_t *rce = &rc->entry[i];
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            rce->pict_type = SLICE_TYPE_P;
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            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;
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            int frame_number;
            char pict_type;
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            int e;
            char *next;
            float qp;

            next= strchr(p, ';');
            if(next){
                (*next)=0; //sscanf is unbelievably slow on looong strings
                next++;
            }
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            e = sscanf(p, " in:%d ", &frame_number);
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            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;
            }
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            rce = &rc->entry[frame_number];
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            rce->direct_mode = 0;
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            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 d:%c",
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                   &pict_type, &qp, &rce->i_tex_bits, &rce->p_tex_bits,
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                   &rce->mv_bits, &rce->misc_bits, &rce->i_count, &rce->p_count,
                   &rce->s_count, &rce->direct_mode);
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            switch(pict_type){
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                case 'I': rce->kept_as_ref = 1;
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                case 'i': rce->pict_type = SLICE_TYPE_I; break;
                case 'P': rce->pict_type = SLICE_TYPE_P; break;
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                case 'B': rce->kept_as_ref = 1;
                case 'b': rce->pict_type = SLICE_TYPE_B; break;
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                default:  e = -1; break;
            }
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            if(e < 10){
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                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;
        }

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        x264_free(stats_buf);
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        if(h->param.rc.b_cbr)
        {
            if(init_pass2(h) < 0) return -1;
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        } /* else we're using constant quant, so no need to run the bitrate allocation */
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    }

    /* Open output file */
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    /* 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 */
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    if( h->param.rc.b_stat_write )
    {
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        char *p;

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        rc->psz_stat_file_tmpname = x264_malloc( strlen(h->param.rc.psz_stat_out) + 6 );
        strcpy( rc->psz_stat_file_tmpname, h->param.rc.psz_stat_out );
        strcat( rc->psz_stat_file_tmpname, ".temp" );
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        rc->p_stat_file_out = fopen( rc->psz_stat_file_tmpname, "wb" );
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        if( rc->p_stat_file_out == NULL )
        {
            x264_log(h, X264_LOG_ERROR, "ratecontrol_init: can't open stats file\n");
            return -1;
        }
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        p = x264_param2string( &h->param, 1 );
        fprintf( rc->p_stat_file_out, "#options: %s\n", p );
        x264_free( p );
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    }
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    return 0;
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}

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static int parse_zones( x264_t *h )
{
    x264_ratecontrol_t *rc = h->rc;
    int i;
    if( h->param.rc.psz_zones && !h->param.rc.i_zones )
    {
        char *p;
        h->param.rc.i_zones = 1;
        for( p = h->param.rc.psz_zones; *p; p++ )
            h->param.rc.i_zones += (*p == '/');
        h->param.rc.zones = x264_malloc( h->param.rc.i_zones * sizeof(x264_zone_t) );
        p = h->param.rc.psz_zones;
        for( i = 0; i < h->param.rc.i_zones; i++)
        {
            x264_zone_t *z = &h->param.rc.zones[i];
            if( 3 == sscanf(p, "%u,%u,q=%u", &z->i_start, &z->i_end, &z->i_qp) )
                z->b_force_qp = 1;
            else if( 3 == sscanf(p, "%u,%u,b=%f", &z->i_start, &z->i_end, &z->f_bitrate_factor) )
                z->b_force_qp = 0;
            else
            {
                char *slash = strchr(p, '/');
                if(slash) *slash = '\0';
                x264_log( h, X264_LOG_ERROR, "invalid zone: \"%s\"\n", p );
                return -1;
            }
            p = strchr(p, '/') + 1;
        }
    }

    if( h->param.rc.i_zones > 0 )
    {
        for( i = 0; i < h->param.rc.i_zones; i++ )
        {
            x264_zone_t z = h->param.rc.zones[i];
            if( z.i_start < 0 || z.i_start > z.i_end )
            {
                x264_log( h, X264_LOG_ERROR, "invalid zone: start=%d end=%d\n",
                          z.i_start, z.i_end );
                return -1;
            }
            else if( !z.b_force_qp && z.f_bitrate_factor <= 0 )
            {
                x264_log( h, X264_LOG_ERROR, "invalid zone: bitrate_factor=%f\n",
                          z.f_bitrate_factor );
                return -1;
            }
        }

        rc->i_zones = h->param.rc.i_zones;
        rc->zones = x264_malloc( rc->i_zones * sizeof(x264_zone_t) );
        memcpy( rc->zones, h->param.rc.zones, rc->i_zones * sizeof(x264_zone_t) );
    }

    return 0;
}

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void x264_ratecontrol_summary( x264_t *h )
{
    x264_ratecontrol_t *rc = h->rc;
    if( rc->b_abr && !h->param.rc.i_rf_constant && !h->param.rc.i_vbv_max_bitrate )
    {
        double base_cplx = h->mb.i_mb_count * (h->param.i_bframe ? 120 : 80);
        x264_log( h, X264_LOG_INFO, "final ratefactor: %.2f\n", 
                  qscale2qp( pow( base_cplx, 1 - h->param.rc.f_qcompress )
                             * rc->cplxr_sum / rc->wanted_bits_window ) );
    }
}

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void x264_ratecontrol_delete( x264_t *h )
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{
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    x264_ratecontrol_t *rc = h->rc;
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    if( rc->p_stat_file_out )
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    {
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        fclose( rc->p_stat_file_out );
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        if( h->i_frame >= rc->num_entries - h->param.i_bframe )
            if( rename( rc->psz_stat_file_tmpname, h->param.rc.psz_stat_out ) != 0 )
            {
                x264_log( h, X264_LOG_ERROR, "failed to rename \"%s\" to \"%s\"\n",
                          rc->psz_stat_file_tmpname, h->param.rc.psz_stat_out );
            }
        x264_free( rc->psz_stat_file_tmpname );
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    }
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    x264_free( rc->entry );
    x264_free( rc->zones );
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    x264_free( rc );
}

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/* Before encoding a frame, choose a QP for it */
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void x264_ratecontrol_start( x264_t *h, int i_slice_type, int i_force_qp )
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{
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    x264_ratecontrol_t *rc = h->rc;
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    ratecontrol_entry_t *rce = NULL;
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    x264_cpu_restore( h->param.cpu );

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    rc->qp_force = i_force_qp;
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    rc->slice_type = i_slice_type;
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    if( h->param.rc.b_stat_read )
    {
        int frame = h->fenc->i_frame;
        assert( frame >= 0 && frame < rc->num_entries );
        rce = h->rc->rce = &h->rc->entry[frame];

        if( i_slice_type == SLICE_TYPE_B
            && h->param.analyse.i_direct_mv_pred == X264_DIRECT_PRED_AUTO )
        {
            h->sh.b_direct_spatial_mv_pred = ( rce->direct_mode == 's' );
            h->mb.b_direct_auto_read = ( rce->direct_mode == 's' || rce->direct_mode == 't' );
        }
    }

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    if( h->fdec->i_row_bits )
    {
        memset( h->fdec->i_row_bits, 0, h->sps->i_mb_height * sizeof(int) );
    }

    if( i_slice_type != SLICE_TYPE_B )
    {
        rc->bframe_bits = 0;
        rc->bframes = 0;
        while( h->frames.current[rc->bframes] && IS_X264_TYPE_B(h->frames.current[rc->bframes]->i_type) )
            rc->bframes++;
    }

    rc->qpa = 0;

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    if( i_force_qp )
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    {
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        rc->qpm = rc->qp = i_force_qp - 1;
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    }
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    else if( rc->b_abr )
    {
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        rc->qpm = rc->qp =
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            x264_clip3( (int)(qscale2qp( rate_estimate_qscale( h, i_slice_type ) ) + .5), 0, 51 );
    }
    else if( rc->b_2pass )
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    {
        rce->new_qscale = rate_estimate_qscale( h, i_slice_type );
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        rc->qpm = rc->qp = rce->new_qp =
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            x264_clip3( (int)(qscale2qp(rce->new_qscale) + 0.5), 0, 51 );
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    }
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    else /* CQP */
    {
        int q;
        if( i_slice_type == SLICE_TYPE_B && h->fdec->b_kept_as_ref )
            q = ( rc->qp_constant[ SLICE_TYPE_B ] + rc->qp_constant[ SLICE_TYPE_P ] ) / 2;
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        else
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            q = rc->qp_constant[ i_slice_type ];
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        rc->qpm = rc->qp = q;
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    }
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}

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double predict_row_size( x264_t *h, int y, int qp )
{
    /* average between two predictors:
     * absolute SATD, and scaled bit cost of the colocated row in the previous frame */
    x264_ratecontrol_t *rc = h->rc;
    double pred_s = predict_size( rc->row_pred, qp2qscale(qp), h->fdec->i_row_satd[y] );
    double pred_t = 0;
    if( rc->slice_type != SLICE_TYPE_I 
        && h->fref0[0]->i_type == h->fdec->i_type
        && h->fref0[0]->i_row_satd[y] > 0 )
    {
        pred_t = h->fref0[0]->i_row_bits[y] * h->fdec->i_row_satd[y] / h->fref0[0]->i_row_satd[y]
                 * qp2qscale(h->fref0[0]->i_row_qp[y]) / qp2qscale(qp);
    }
    if( pred_t == 0 )
        pred_t = pred_s;

    return (pred_s + pred_t) / 2;
}

double predict_row_size_sum( x264_t *h, int y, int qp )
{
    int i;
    double bits = 0;
    for( i = h->rc->first_row; i <= y; i++ )
        bits += h->fdec->i_row_bits[i];
    for( i = y+1; i <= h->rc->last_row; i++ )
        bits += predict_row_size( h, i, qp );
    return bits;
}

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void x264_ratecontrol_mb( x264_t *h, int bits )
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{
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    x264_ratecontrol_t *rc = h->rc;
    const int y = h->mb.i_mb_y;

    x264_cpu_restore( h->param.cpu );

    h->fdec->i_row_bits[y] += bits;
    rc->qpa += rc->qpm;

    if( h->mb.i_mb_x != h->sps->i_mb_width - 1 || !rc->b_vbv )
        return;

    h->fdec->i_row_qp[y] = rc->qpm;

    if( rc->slice_type == SLICE_TYPE_B )
    {
        /* B-frames shouldn't use lower QP than their reference frames */
        if( y < rc->last_row )
        {
            rc->qpm = X264_MAX( rc->qp,
                      X264_MIN( h->fref0[0]->i_row_qp[y+1],
                                h->fref1[0]->i_row_qp[y+1] ));
        }
    }
    else
    {
        update_predictor( rc->row_pred, qp2qscale(rc->qpm), h->fdec->i_row_satd[y], h->fdec->i_row_bits[y] );

        /* tweak quality based on difference from predicted size */
        if( y < rc->last_row && h->stat.i_slice_count[rc->slice_type] > 0 )
        {
            int prev_row_qp = h->fdec->i_row_qp[y];
            int b0 = predict_row_size_sum( h, y, rc->qpm );
            int b1 = b0;
            int i_qp_max = X264_MIN( prev_row_qp + h->param.rc.i_qp_step, h->param.rc.i_qp_max );
            int i_qp_min = X264_MAX( prev_row_qp - h->param.rc.i_qp_step, h->param.rc.i_qp_min );
            float buffer_left_planned = rc->buffer_fill - rc->frame_size_planned;

            while( rc->qpm < i_qp_max
                   && (b1 > rc->frame_size_planned * 1.15
                    || (rc->buffer_fill - b1 < buffer_left_planned * 0.5)))
            {
                rc->qpm ++;
                b1 = predict_row_size_sum( h, y, rc->qpm );
            }

            while( rc->qpm > i_qp_min
                   && buffer_left_planned > rc->buffer_size * 0.4
                   && ((b1 < rc->frame_size_planned * 0.8 && rc->qpm <= prev_row_qp)
                     || b1 < (rc->buffer_fill - rc->buffer_size + rc->buffer_rate) * 1.1) )
            {
                rc->qpm --;
                b1 = predict_row_size_sum( h, y, rc->qpm );
            }
        }
    }
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}

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int x264_ratecontrol_qp( x264_t *h )
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{
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    return h->rc->qpm;
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}
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/* In 2pass, force the same frame types as in the 1st pass */
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int x264_ratecontrol_slice_type( x264_t *h, int frame_num )
{
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    x264_ratecontrol_t *rc = h->rc;
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    if( h->param.rc.b_stat_read )
    {
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        if( frame_num >= rc->num_entries )
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        {
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            /* We could try to initialize everything required for ABR and
             * adaptive B-frames, but that would be complicated.
             * So just calculate the average QP used so far. */

            h->param.rc.i_qp_constant = (h->stat.i_slice_count[SLICE_TYPE_P] == 0) ? 24
                                      : 1 + h->stat.i_slice_qp[SLICE_TYPE_P] / h->stat.i_slice_count[SLICE_TYPE_P];
            rc->qp_constant[SLICE_TYPE_P] = x264_clip3( h->param.rc.i_qp_constant, 0, 51 );
            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 );

            x264_log(h, X264_LOG_ERROR, "2nd pass has more frames than 1st pass (%d)\n", rc->num_entries);
            x264_log(h, X264_LOG_ERROR, "continuing anyway, at constant QP=%d\n", h->param.rc.i_qp_constant);
            if( h->param.b_bframe_adaptive )
                x264_log(h, X264_LOG_ERROR, "disabling adaptive B-frames\n");

            rc->b_abr = 0;
            rc->b_2pass = 0;
            h->param.rc.b_cbr = 0;
            h->param.rc.b_stat_read = 0;
            h->param.b_bframe_adaptive = 0;
            if( h->param.i_bframe > 1 )
                h->param.i_bframe = 1;
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            return X264_TYPE_P;
        }
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        switch( rc->entry[frame_num].pict_type )
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        {
            case SLICE_TYPE_I:
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                return rc->entry[frame_num].kept_as_ref ? X264_TYPE_IDR : X264_TYPE_I;
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            case SLICE_TYPE_B:
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                return rc->entry[frame_num].kept_as_ref ? X264_TYPE_BREF : X264_TYPE_B;
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            case SLICE_TYPE_P:
            default:
                return X264_TYPE_P;
        }
    }
    else
    {
        return X264_TYPE_AUTO;
    }
}

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/* After encoding one frame, save stats and update ratecontrol state */
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void x264_ratecontrol_end( x264_t *h, int bits )
{
    x264_ratecontrol_t *rc = h->rc;
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    const int *mbs = h->stat.frame.i_mb_count;
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    int i;
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    x264_cpu_restore( h->param.cpu );

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    h->stat.frame.i_mb_count_skip = mbs[P_SKIP] + mbs[B_SKIP];
    h->stat.frame.i_mb_count_i = mbs[I_16x16] + mbs[I_8x8] + mbs[I_4x4];
    h->stat.frame.i_mb_count_p = mbs[P_L0] + mbs[P_8x8];
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    for( i = B_DIRECT; i < B_8x8; i++ )
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        h->stat.frame.i_mb_count_p += mbs[i];
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    if( rc->b_vbv )
    {
        for( i = 1; i < h->param.i_threads; i++ )
            rc->qpa += rc[i].qpa;
        rc->qpa /= h->mb.i_mb_count;
    }
    else
        rc->qpa = rc->qp;
    h->fdec->f_qp_avg = rc->qpa;

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    if( h->param.rc.b_stat_write )
    {
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        char c_type = rc->slice_type==SLICE_TYPE_I ? (h->fenc->i_poc==0 ? 'I' : 'i')
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                    : rc->slice_type==SLICE_TYPE_P ? 'P'
                    : h->fenc->b_kept_as_ref ? 'B' : 'b';
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        int dir_frame = h->stat.frame.i_direct_score[1] - h->stat.frame.i_direct_score[0];
        int dir_avg = h->stat.i_direct_score[1] - h->stat.i_direct_score[0];
        char c_direct = h->mb.b_direct_auto_write ?
                        ( dir_frame>0 ? 's' : dir_frame<0 ? 't' : 
                          dir_avg>0 ? 's' : dir_avg<0 ? 't' : '-' )
                        : '-';
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        fprintf( rc->p_stat_file_out,
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                 "in:%d out:%d type:%c q:%.2f itex:%d ptex:%d mv:%d misc:%d imb:%d pmb:%d smb:%d d:%c;\n",
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                 h->fenc->i_frame, h->i_frame,
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                 c_type, rc->qpa,
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                 h->stat.frame.i_itex_bits, h->stat.frame.i_ptex_bits,
                 h->stat.frame.i_hdr_bits, h->stat.frame.i_misc_bits,
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                 h->stat.frame.i_mb_count_i,
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                 h->stat.frame.i_mb_count_p,
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                 h->stat.frame.i_mb_count_skip,
                 c_direct);
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    }

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    if( rc->b_abr )
    {
        if( rc->slice_type != SLICE_TYPE_B )
            rc->cplxr_sum += bits * qp2qscale(rc->qpa) / rc->last_rceq;
        else
        {
            /* Depends on the fact that B-frame's QP is an offset from the following P-frame's.
             * Not perfectly accurate with B-refs, but good enough. */
            rc->cplxr_sum += bits * qp2qscale(rc->qpa) / (rc->last_rceq * fabs(h->param.rc.f_pb_factor));
        }
        rc->cplxr_sum *= rc->cbr_decay;
        rc->wanted_bits_window += rc->bitrate / rc->fps;
        rc->wanted_bits_window *= rc->cbr_decay;

        rc->accum_p_qp   *= .95;
        rc->accum_p_norm *= .95;
        rc->accum_p_norm += 1;
        if( rc->slice_type == SLICE_TYPE_I )
            rc->accum_p_qp += rc->qpa * fabs(h->param.rc.f_ip_factor);
        else
            rc->accum_p_qp += rc->qpa;
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    }

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    if( rc->b_2pass )
    {
        rc->expected_bits_sum += qscale2bits( rc->rce, qp2qscale(rc->rce->new_qp) );
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    }

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    if( rc->b_vbv )
    {
        if( rc->slice_type == SLICE_TYPE_B )
        {
            rc->bframe_bits += bits;
            if( !h->frames.current[0] || !IS_X264_TYPE_B(h->frames.current[0]->i_type) )
                update_predictor( &rc->pred_b_from_p, qp2qscale(rc->qpa), h->fref1[0]->i_satd, rc->bframe_bits / rc->bframes );
        }
        else
        {
            /* Update row predictor based on data collected by other threads. */
            int y;
            for( y = rc->last_row+1; y < h->sps->i_mb_height; y++ )
                update_predictor( rc->row_pred, qp2qscale(h->fdec->i_row_qp[y]), h->fdec->i_row_satd[y], h->fdec->i_row_bits[y] );
            rc->row_preds[rc->slice_type] = *rc->row_pred;
        }
    }

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    update_vbv( h, bits );
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    if( rc->slice_type != SLICE_TYPE_B )
        rc->last_non_b_pict_type = rc->slice_type;
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}
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/****************************************************************************
 * 2 pass functions
 ***************************************************************************/
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double x264_eval( char *s, double *const_value, const char **const_name,
                  double (**func1)(void *, double), const char **func1_name,
                  double (**func2)(void *, double, double), char **func2_name,
                  void *opaque );

/**
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 * modify the bitrate curve from pass1 for one frame
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 */
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static double get_qscale(x264_t *h, ratecontrol_entry_t *rce, double rate_factor, int frame_num)
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{
    x264_ratecontrol_t *rcc= h->rc;
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    const int pict_type = rce->pict_type;
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    double q;
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    int i;
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    double const_values[]={
        rce->i_tex_bits * rce->qscale,
        rce->p_tex_bits * rce->qscale,
        (rce->i_tex_bits + rce->p_tex_bits) * rce->qscale,
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        rce->mv_bits * rce->qscale,
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        (double)rce->i_count / rcc->nmb,
        (double)rce->p_count / rcc->nmb,
        (double)rce->s_count / rcc->nmb,
        rce->pict_type == SLICE_TYPE_I,
        rce->pict_type == SLICE_TYPE_P,
        rce->pict_type == SLICE_TYPE_B,
        h->param.rc.f_qcompress,
        rcc->i_cplx_sum[SLICE_TYPE_I] / rcc->frame_count[SLICE_TYPE_I],
        rcc->i_cplx_sum[SLICE_TYPE_P] / rcc->frame_count[SLICE_TYPE_P],
        rcc->p_cplx_sum[SLICE_TYPE_P] / rcc->frame_count[SLICE_TYPE_P],
        rcc->p_cplx_sum[SLICE_TYPE_B] / rcc->frame_count[SLICE_TYPE_B],
        (rcc->i_cplx_sum[pict_type] + rcc->p_cplx_sum[pict_type]) / rcc->frame_count[pict_type],
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        rce->blurred_complexity,
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        0
    };
    static const char *const_names[]={
        "iTex",
        "pTex",
        "tex",
        "mv",
        "iCount",
        "pCount",
        "sCount",
        "isI",
        "isP",
        "isB",
        "qComp",
        "avgIITex",
        "avgPITex",
        "avgPPTex",
        "avgBPTex",
        "avgTex",
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        "blurCplx",
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        NULL
    };
    static double (*func1[])(void *, double)={
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//      (void *)bits2qscale,
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        (void *)qscale2bits,
        NULL
    };
    static const char *func1_names[]={
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//      "bits2qp",
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        "qp2bits",
        NULL
    };

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    q = x264_eval((char*)h->param.rc.psz_rc_eq, const_values, const_names, func1, func1_names, NULL, NULL, rce);
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    // avoid NaN's in the rc_eq
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    if(!isfinite(q) || rce->i_tex_bits + rce->p_tex_bits + rce->mv_bits == 0)
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        q = rcc->last_qscale;
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    else {
        rcc->last_rceq = q;
        q /= rate_factor;
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        rcc->last_qscale = q;
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    }

    for( i = rcc->i_zones-1; i >= 0; i-- )
    {
        x264_zone_t *z = &rcc->zones[i];
        if( frame_num >= z->i_start && frame_num <= z->i_end )
        {
            if( z->b_force_qp )
                q = qp2qscale(z->i_qp);
            else
                q /= z->f_bitrate_factor;
            break;
        }
    }
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    return q;
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}

static double get_diff_limited_q(x264_t *h, ratecontrol_entry_t *rce, double q)
{
    x264_ratecontrol_t *rcc = h->rc;
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    const int pict_type = rce->pict_type;
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    // force I/B quants as a function of P quants
    const double last_p_q    = rcc->last_qscale_for[SLICE_TYPE_P];
    const double last_non_b_q= rcc->last_qscale_for[rcc->last_non_b_pict_type];
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    if( pict_type == SLICE_TYPE_I )
    {
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        double iq = q;
        double pq = qp2qscale( rcc->accum_p_qp / rcc->accum_p_norm );
        double ip_factor = fabs( h->param.rc.f_ip_factor );
        /* don't apply ip_factor if the following frame is also I */
        if( rcc->accum_p_norm <= 0 )
            q = iq;
        else if( h->param.rc.f_ip_factor < 0 )
            q = iq / ip_factor;
        else if( rcc->accum_p_norm >= 1 )
            q = pq / ip_factor;
        else
            q = rcc->accum_p_norm * pq / ip_factor + (1 - rcc->accum_p_norm) * iq;
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    }
    else if( pict_type == SLICE_TYPE_B )
    {
        if( h->param.rc.f_pb_factor > 0 )
            q = last_non_b_q;
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        if( !rce->kept_as_ref )
            q *= fabs( h->param.rc.f_pb_factor );
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    }
    else if( pict_type == SLICE_TYPE_P
             && rcc->last_non_b_pict_type == SLICE_TYPE_P
             && rce->i_tex_bits + rce->p_tex_bits == 0 )
    {
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        q = last_p_q;
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    }