ratecontrol.c 8.59 KB
Newer Older
Laurent Aimar's avatar
Laurent Aimar committed
1 2 3 4 5 6
/*****************************************************************************
 * ratecontrol.c: h264 encoder library (Rate Control)
 *****************************************************************************
 * Copyright (C) 2003 Laurent Aimar
 * $Id: ratecontrol.c,v 1.1 2004/06/03 19:27:08 fenrir Exp $
 *
7
 * Authors: Mns Rullgrd <mru@mru.ath.cx>
Laurent Aimar's avatar
Laurent Aimar committed
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
 *
 * 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.
 *****************************************************************************/

24 25
#define _ISOC99_SOURCE

Laurent Aimar's avatar
Laurent Aimar committed
26 27 28
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
29 30
#include <math.h>
#include <limits.h>
Laurent Aimar's avatar
Laurent Aimar committed
31 32

#include "../core/common.h"
33
#include "../core/cpu.h"
Laurent Aimar's avatar
Laurent Aimar committed
34 35
#include "ratecontrol.h"

36 37
#define DEBUG_RC 0

38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68
struct x264_ratecontrol_t
{
    /* constants */
    float fps;
    int gop_size;
    int bitrate;
    int nmb;                    /* number of MBs */
    int buffer_size;
    int rcbufrate;
    int init_qp;

    int gop_qp;
    int buffer_fullness;
    int frames;                 /* frames in current gop */
    int pframes;
    int slice_type;
    int mb;                     /* MBs processed in current frame */
    int bits_gop;               /* allocated bits current gop */
    int bits_last_gop;          /* bits consumed in gop */
    int qp;                     /* qp for current frame */
    int qpm;                    /* qp for next MB */
    int qpa;                    /* average qp for last frame */
    int qps;
    int qp_avg_p;               /* average QP for P frames */
    int qp_last_p;
    int fbits;                  /* bits allocated for current frame */
    int ufbits;                 /* bits used for current frame */
    int nzcoeffs;               /* # of 0-quantized coefficients */
    int ncoeffs;                /* total # of coefficients */
    int overhead;
};
Laurent Aimar's avatar
Laurent Aimar committed
69

70
int x264_ratecontrol_new( x264_t *h )
Laurent Aimar's avatar
Laurent Aimar committed
71 72
{
    x264_ratecontrol_t *rc = x264_malloc( sizeof( x264_ratecontrol_t ) );
73 74 75 76 77 78 79 80 81 82 83 84
    float bpp;

    memset(rc, 0, sizeof(*rc));

    rc->fps = h->param.f_fps > 0.1 ? h->param.f_fps : 25.0f;
    rc->gop_size = h->param.i_iframe;
    rc->bitrate = h->param.i_bitrate * 1000;
    rc->nmb = ((h->param.i_width + 15) / 16) * ((h->param.i_height + 15) / 16);

    rc->qp = h->param.i_qp_constant;
    rc->qpa = rc->qp;
    rc->qpm = rc->qp;
Laurent Aimar's avatar
Laurent Aimar committed
85

86 87 88 89 90
    rc->buffer_size = h->param.i_rc_buffer_size;
    if(rc->buffer_size <= 0)
        rc->buffer_size = rc->bitrate / 2;
    rc->buffer_fullness = h->param.i_rc_init_buffer;
    rc->rcbufrate = rc->bitrate / rc->fps;
Laurent Aimar's avatar
Laurent Aimar committed
91

92 93 94 95 96 97 98 99 100 101
    bpp = rc->bitrate / (rc->fps * h->param.i_width * h->param.i_height);
    if(bpp <= 0.6)
        rc->init_qp = 31;
    else if(bpp <= 1.4)
        rc->init_qp = 25;
    else if(bpp <= 2.4)
        rc->init_qp = 20;
    else
        rc->init_qp = 10;
    rc->gop_qp = rc->init_qp;
Laurent Aimar's avatar
Laurent Aimar committed
102

103
    rc->bits_last_gop = 0;
Laurent Aimar's avatar
Laurent Aimar committed
104

105 106 107 108
#if DEBUG_RC
    fprintf(stderr, "%f fps, %i bps, bufsize %i\n",
         rc->fps, rc->bitrate, rc->buffer_size);
#endif
109 110 111 112

    h->rc = rc;

    return 0;
Laurent Aimar's avatar
Laurent Aimar committed
113 114
}

115
void x264_ratecontrol_delete( x264_t *h )
Laurent Aimar's avatar
Laurent Aimar committed
116
{
117
    x264_ratecontrol_t *rc = h->rc;
Laurent Aimar's avatar
Laurent Aimar committed
118 119 120
    x264_free( rc );
}

121
void x264_ratecontrol_start( x264_t *h, int i_slice_type )
Laurent Aimar's avatar
Laurent Aimar committed
122
{
123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201
    x264_ratecontrol_t *rc = h->rc;
    int gframes, iframes, pframes, bframes;
    int minbits, maxbits;
    int gbits, fbits;
    int zn = 0;
    float kp;
    int gbuf;

    if(!h->param.b_cbr)
        return;

    x264_cpu_restore( h->param.cpu );

    rc->slice_type = i_slice_type;

    switch(i_slice_type){
    case SLICE_TYPE_I:
        gbuf = rc->buffer_fullness + (rc->gop_size-1) * rc->rcbufrate;
        rc->bits_gop = gbuf - rc->buffer_size / 2;

        if(!rc->mb && rc->pframes){
            int qp = (float) rc->qp_avg_p / rc->pframes + 0.5;
#if 0 /* JM does this without explaining why */
            int gdq = (float) rc->gop_size / 15 + 0.5;
            if(gdq > 2)
                gdq = 2;
            qp -= gdq;
            if(qp > rc->qp_last_p - 2)
                qp--;
#endif
            qp = x264_clip3(qp, rc->gop_qp - 4, rc->gop_qp + 4);
            qp =
                x264_clip3(qp, h->param.i_qp_min, h->param.i_qp_max);
            rc->gop_qp = qp;
        } else {
            rc->gop_qp = rc->init_qp;
        }

        kp = h->param.f_ip_factor * h->param.f_pb_factor;

        rc->bits_last_gop = 0;
        rc->frames = 0;
        rc->pframes = 0;
        rc->qp_avg_p = 0;
        break;

    case SLICE_TYPE_P:
        kp = h->param.f_pb_factor;
        break;

    case SLICE_TYPE_B:
        kp = 1.0;
        break;

    default:
        fprintf(stderr, "x264: ratecontrol: unknown slice type %i\n",
                i_slice_type);
        kp = 1.0;
        break;
    }

    gframes = rc->gop_size - rc->frames;
    iframes = gframes / rc->gop_size;
    pframes = gframes / (h->param.i_bframe + 1) - iframes;
    bframes = gframes - pframes - iframes;

    gbits = rc->bits_gop - rc->bits_last_gop;
    fbits = kp * gbits /
        (h->param.f_ip_factor * h->param.f_pb_factor * iframes +
         h->param.f_pb_factor * pframes + bframes);

    minbits = rc->buffer_fullness + rc->rcbufrate - rc->buffer_size;
    if(minbits < 0)
        minbits = 0;
    maxbits = rc->buffer_fullness;
    rc->fbits = x264_clip3(fbits, minbits, maxbits);

    if(i_slice_type == SLICE_TYPE_I){
        rc->qp = rc->gop_qp;
202
    } else if(rc->ncoeffs && rc->ufbits){
203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224
        int dqp;

        zn = rc->ncoeffs -
            rc->fbits * (rc->ncoeffs - rc->nzcoeffs) / rc->ufbits;
        dqp = h->param.i_rc_sens * exp2f((float) rc->qpa / 6) *
            (zn - rc->nzcoeffs) / rc->nzcoeffs;
        dqp = x264_clip3(dqp, -h->param.i_qp_step, h->param.i_qp_step);
        rc->qp = rc->qpa + dqp;
    }

    if(rc->fbits > 0.8 * maxbits)
        rc->qp += 1;
    else if(rc->fbits > 0.9 * maxbits)
        rc->qp += 2;
    else if(rc->fbits < 1.2 * minbits)
        rc->qp -= 1;
    else if(rc->fbits < 1.1 * minbits)
        rc->qp -= 2;

    rc->qp = x264_clip3(rc->qp, h->param.i_qp_min, h->param.i_qp_max);
    rc->qpm = rc->qp;

225 226 227 228
#if DEBUG_RC
    fprintf(stderr, "fbits=%i, qp=%i, z=%i, min=%i, max=%i\n",
         rc->fbits, rc->qpm, zn, minbits, maxbits);
#endif
229 230 231 232 233 234 235

    rc->fbits -= rc->overhead;
    rc->ufbits = 0;
    rc->ncoeffs = 0;
    rc->nzcoeffs = 0;
    rc->mb = 0;
    rc->qps = 0;
Laurent Aimar's avatar
Laurent Aimar committed
236 237
}

238
void x264_ratecontrol_mb( x264_t *h, int bits )
Laurent Aimar's avatar
Laurent Aimar committed
239
{
240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274
    x264_ratecontrol_t *rc = h->rc;
    int rbits;
    int zn, enz;
    int dqp;
    int i;

    x264_cpu_restore( h->param.cpu );

    rc->qps += rc->qpm;
    rc->ufbits += bits;
    rc->mb++;

    for(i = 0; i < 16 + 8; i++)
        rc->nzcoeffs += 16 - h->mb.cache.non_zero_count[x264_scan8[i]];
    rc->ncoeffs += 16 * (16 + 8);

    if(rc->mb < rc->nmb / 16)
        return;
    else if(rc->mb == rc->nmb)
        return;

    rbits = rc->fbits - rc->ufbits;
/*     if(rbits < 0) */
/*      rbits = 0; */

    zn = (rc->nmb - rc->mb) * 16 * 24;
    if(rc->ufbits)
        zn -= rbits * (rc->ncoeffs - rc->nzcoeffs) / rc->ufbits;
    enz = rc->nzcoeffs * (rc->nmb - rc->mb) / rc->mb;
    dqp = (float) 2*h->param.i_rc_sens * exp2f((float) rc->qps / rc->mb / 6) *
        (zn - enz) / enz;
    rc->qpm = x264_clip3(rc->qpm + dqp, rc->qp - 3, rc->qp + 3);
    if(rbits <= 0)
        rc->qpm++;
    rc->qpm = x264_clip3(rc->qpm, h->param.i_qp_min, h->param.i_qp_max);
Laurent Aimar's avatar
Laurent Aimar committed
275 276
}

277
int  x264_ratecontrol_qp( x264_t *h )
Laurent Aimar's avatar
Laurent Aimar committed
278
{
279 280
    return h->rc->qpm;
}
Laurent Aimar's avatar
Laurent Aimar committed
281

282 283 284
void x264_ratecontrol_end( x264_t *h, int bits )
{
    x264_ratecontrol_t *rc = h->rc;
Laurent Aimar's avatar
Laurent Aimar committed
285

286 287
    if(!h->param.b_cbr)
        return;
Laurent Aimar's avatar
Laurent Aimar committed
288

289 290 291 292
    rc->buffer_fullness += rc->rcbufrate - bits;
    if(rc->buffer_fullness < 0){
        fprintf(stderr, "x264: buffer underflow %i\n", rc->buffer_fullness);
        rc->buffer_fullness = 0;
Laurent Aimar's avatar
Laurent Aimar committed
293 294
    }

295 296 297 298 299
    rc->qpa = rc->qps / rc->mb;
    if(rc->slice_type == SLICE_TYPE_P){
        rc->qp_avg_p += rc->qpa;
        rc->qp_last_p = rc->qpa;
        rc->pframes++;
Laurent Aimar's avatar
Laurent Aimar committed
300 301
    }

302 303
    rc->overhead = bits - rc->ufbits;

304 305 306 307 308
#if DEBUG_RC
    fprintf(stderr, " bits=%i, qp=%i, z=%i, zr=%6.3f, buf=%i\n",
         bits, rc->qpa, rc->nzcoeffs,
         (float) rc->nzcoeffs / rc->ncoeffs, rc->buffer_fullness);
#endif
309 310 311 312

    rc->bits_last_gop += bits;
    rc->frames++;
    rc->mb = 0;
Laurent Aimar's avatar
Laurent Aimar committed
313 314
}