libavcodec/h261enc.c

   1 /*
   2  * H261 encoder
   3  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
   4  * Copyright (c) 2004 Maarten Daniels
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 /**
  24  * @file libavcodec/h261enc.c
  25  * H.261 encoder.
  26  */
  27
  28 #include "dsputil.h"
  29 #include "avcodec.h"
  30 #include "mpegvideo.h"
  31 #include "h261.h"
  32 #include "h261data.h"
  33
  34 extern uint8_t ff_h261_rl_table_store[2][2*MAX_RUN + MAX_LEVEL + 3];
  35
  36 static void h261_encode_block(H261Context * h, DCTELEM * block,
  37                               int n);
  38
  39 int ff_h261_get_picture_format(int width, int height){
  40     // QCIF
  41     if (width == 176 && height == 144)
  42         return 0;
  43     // CIF
  44     else if (width == 352 && height == 288)
  45         return 1;
  46     // ERROR
  47     else
  48         return -1;
  49 }
  50
  51 void ff_h261_encode_picture_header(MpegEncContext * s, int picture_number){
  52     H261Context * h = (H261Context *) s;
  53     int format, temp_ref;
  54
  55     align_put_bits(&s->pb);
  56
  57     /* Update the pointer to last GOB */
  58     s->ptr_lastgob = put_bits_ptr(&s->pb);
  59
  60     put_bits(&s->pb, 20, 0x10); /* PSC */
  61
  62     temp_ref= s->picture_number * (int64_t)30000 * s->avctx->time_base.num /
  63                          (1001 * (int64_t)s->avctx->time_base.den); //FIXME maybe this should use a timestamp
  64     put_sbits(&s->pb, 5, temp_ref); /* TemporalReference */
  65
  66     put_bits(&s->pb, 1, 0); /* split screen off */
  67     put_bits(&s->pb, 1, 0); /* camera  off */
  68     put_bits(&s->pb, 1, 0); /* freeze picture release off */
  69
  70     format = ff_h261_get_picture_format(s->width, s->height);
  71
  72     put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
  73
  74     put_bits(&s->pb, 1, 0); /* still image mode */
  75     put_bits(&s->pb, 1, 0); /* reserved */
  76
  77     put_bits(&s->pb, 1, 0); /* no PEI */
  78     if(format == 0)
  79         h->gob_number = -1;
  80     else
  81         h->gob_number = 0;
  82     h->current_mba = 0;
  83 }
  84
  85 /**
  86  * Encodes a group of blocks header.
  87  */
  88 static void h261_encode_gob_header(MpegEncContext * s, int mb_line){
  89     H261Context * h = (H261Context *)s;
  90     if(ff_h261_get_picture_format(s->width, s->height) == 0){
  91         h->gob_number+=2; // QCIF
  92     }
  93     else{
  94         h->gob_number++; // CIF
  95     }
  96     put_bits(&s->pb, 16, 1); /* GBSC */
  97     put_bits(&s->pb, 4, h->gob_number); /* GN */
  98     put_bits(&s->pb, 5, s->qscale); /* GQUANT */
  99     put_bits(&s->pb, 1, 0); /* no GEI */
 100     h->current_mba = 0;
 101     h->previous_mba = 0;
 102     h->current_mv_x=0;
 103     h->current_mv_y=0;
 104 }
 105
 106 void ff_h261_reorder_mb_index(MpegEncContext* s){
 107     int index= s->mb_x + s->mb_y*s->mb_width;
 108
 109     if(index % 33 == 0)
 110         h261_encode_gob_header(s,0);
 111
 112     /* for CIF the GOB's are fragmented in the middle of a scanline
 113        that's why we need to adjust the x and y index of the macroblocks */
 114     if(ff_h261_get_picture_format(s->width,s->height) == 1){ // CIF
 115         s->mb_x =     index % 11 ; index /= 11;
 116         s->mb_y =     index %  3 ; index /=  3;
 117         s->mb_x+= 11*(index %  2); index /=  2;
 118         s->mb_y+=  3*index;
 119
 120         ff_init_block_index(s);
 121         ff_update_block_index(s);
 122     }
 123 }
 124
 125 static void h261_encode_motion(H261Context * h, int val){
 126     MpegEncContext * const s = &h->s;
 127     int sign, code;
 128     if(val==0){
 129         code = 0;
 130         put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
 131     }
 132     else{
 133         if(val > 15)
 134             val -=32;
 135         if(val < -16)
 136             val+=32;
 137         sign = val < 0;
 138         code = sign ? -val : val;
 139         put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
 140         put_bits(&s->pb,1,sign);
 141     }
 142 }
 143
 144 static inline int get_cbp(MpegEncContext * s,
 145                       DCTELEM block[6][64])
 146 {
 147     int i, cbp;
 148     cbp= 0;
 149     for (i = 0; i < 6; i++) {
 150         if (s->block_last_index[i] >= 0)
 151             cbp |= 1 << (5 - i);
 152     }
 153     return cbp;
 154 }
 155 void ff_h261_encode_mb(MpegEncContext * s,
 156          DCTELEM block[6][64],
 157          int motion_x, int motion_y)
 158 {
 159     H261Context * h = (H261Context *)s;
 160     int mvd, mv_diff_x, mv_diff_y, i, cbp;
 161     cbp = 63; // avoid warning
 162     mvd = 0;
 163
 164     h->current_mba++;
 165     h->mtype = 0;
 166
 167     if (!s->mb_intra){
 168         /* compute cbp */
 169         cbp= get_cbp(s, block);
 170
 171         /* mvd indicates if this block is motion compensated */
 172         mvd = motion_x | motion_y;
 173
 174         if((cbp | mvd | s->dquant ) == 0) {
 175             /* skip macroblock */
 176             s->skip_count++;
 177             h->current_mv_x=0;
 178             h->current_mv_y=0;
 179             return;
 180         }
 181     }
 182
 183     /* MB is not skipped, encode MBA */
 184     put_bits(&s->pb, h261_mba_bits[(h->current_mba-h->previous_mba)-1], h261_mba_code[(h->current_mba-h->previous_mba)-1]);
 185
 186     /* calculate MTYPE */
 187     if(!s->mb_intra){
 188         h->mtype++;
 189
 190         if(mvd || s->loop_filter)
 191             h->mtype+=3;
 192         if(s->loop_filter)
 193             h->mtype+=3;
 194         if(cbp || s->dquant)
 195             h->mtype++;
 196         assert(h->mtype > 1);
 197     }
 198
 199     if(s->dquant)
 200         h->mtype++;
 201
 202     put_bits(&s->pb, h261_mtype_bits[h->mtype], h261_mtype_code[h->mtype]);
 203
 204     h->mtype = h261_mtype_map[h->mtype];
 205
 206     if(IS_QUANT(h->mtype)){
 207         ff_set_qscale(s,s->qscale+s->dquant);
 208         put_bits(&s->pb, 5, s->qscale);
 209     }
 210
 211     if(IS_16X16(h->mtype)){
 212         mv_diff_x = (motion_x >> 1) - h->current_mv_x;
 213         mv_diff_y = (motion_y >> 1) - h->current_mv_y;
 214         h->current_mv_x = (motion_x >> 1);
 215         h->current_mv_y = (motion_y >> 1);
 216         h261_encode_motion(h,mv_diff_x);
 217         h261_encode_motion(h,mv_diff_y);
 218     }
 219
 220     h->previous_mba = h->current_mba;
 221
 222     if(HAS_CBP(h->mtype)){
 223         assert(cbp>0);
 224         put_bits(&s->pb,h261_cbp_tab[cbp-1][1],h261_cbp_tab[cbp-1][0]);
 225     }
 226     for(i=0; i<6; i++) {
 227         /* encode each block */
 228         h261_encode_block(h, block[i], i);
 229     }
 230
 231     if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
 232         h->current_mv_x=0;
 233         h->current_mv_y=0;
 234     }
 235 }
 236
 237 void ff_h261_encode_init(MpegEncContext *s){
 238     static int done = 0;
 239
 240     if (!done) {
 241         done = 1;
 242         init_rl(&h261_rl_tcoeff, ff_h261_rl_table_store);
 243     }
 244
 245     s->min_qcoeff= -127;
 246     s->max_qcoeff=  127;
 247     s->y_dc_scale_table=
 248     s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
 249 }
 250
 251
 252 /**
 253  * encodes a 8x8 block.
 254  * @param block the 8x8 block
 255  * @param n block index (0-3 are luma, 4-5 are chroma)
 256  */
 257 static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
 258     MpegEncContext * const s = &h->s;
 259     int level, run, i, j, last_index, last_non_zero, sign, slevel, code;
 260     RLTable *rl;
 261
 262     rl = &h261_rl_tcoeff;
 263     if (s->mb_intra) {
 264         /* DC coef */
 265         level = block[0];
 266         /* 255 cannot be represented, so we clamp */
 267         if (level > 254) {
 268             level = 254;
 269             block[0] = 254;
 270         }
 271         /* 0 cannot be represented also */
 272         else if (level < 1) {
 273             level = 1;
 274             block[0] = 1;
 275         }
 276         if (level == 128)
 277             put_bits(&s->pb, 8, 0xff);
 278         else
 279             put_bits(&s->pb, 8, level);
 280         i = 1;
 281     } else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
 282         //special case
 283         put_bits(&s->pb,2,block[0]>0 ? 2 : 3 );
 284         i = 1;
 285     } else {
 286         i = 0;
 287     }
 288
 289     /* AC coefs */
 290     last_index = s->block_last_index[n];
 291     last_non_zero = i - 1;
 292     for (; i <= last_index; i++) {
 293         j = s->intra_scantable.permutated[i];
 294         level = block[j];
 295         if (level) {
 296             run = i - last_non_zero - 1;
 297             sign = 0;
 298             slevel = level;
 299             if (level < 0) {
 300                 sign = 1;
 301                 level = -level;
 302             }
 303             code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level);
 304             if(run==0 && level < 16)
 305             code+=1;
 306             put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
 307             if (code == rl->n) {
 308                 put_bits(&s->pb, 6, run);
 309                 assert(slevel != 0);
 310                 assert(level <= 127);
 311                 put_sbits(&s->pb, 8, slevel);
 312             } else {
 313                 put_bits(&s->pb, 1, sign);
 314             }
 315             last_non_zero = i;
 316         }
 317     }
 318     if(last_index > -1){
 319         put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]);// END OF BLOCK
 320     }
 321 }
 322
 323 AVCodec h261_encoder = {
 324     "h261",
 325     CODEC_TYPE_VIDEO,
 326     CODEC_ID_H261,
 327     sizeof(H261Context),
 328     MPV_encode_init,
 329     MPV_encode_picture,
 330     MPV_encode_end,
 331     .pix_fmts= (enum PixelFormat[]){PIX_FMT_YUV420P, PIX_FMT_NONE},
 332     .long_name= NULL_IF_CONFIG_SMALL("H.261"),
 333 };
 334