FFmpeg: libavcodec/h261enc.c Source File

00001 /*
00002  * H261 encoder
00003  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
00004  * Copyright (c) 2004 Maarten Daniels
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00028 #include "dsputil.h"
00029 #include "avcodec.h"
00030 #include "mpegvideo.h"
00031 #include "h263.h"
00032 #include "h261.h"
00033 #include "h261data.h"
00034 
00035 extern uint8_t ff_h261_rl_table_store[2][2*MAX_RUN + MAX_LEVEL + 3];
00036 
00037 static void h261_encode_block(H261Context * h, DCTELEM * block,
00038                               int n);
00039 
00040 int ff_h261_get_picture_format(int width, int height){
00041     // QCIF
00042     if (width == 176 && height == 144)
00043         return 0;
00044     // CIF
00045     else if (width == 352 && height == 288)
00046         return 1;
00047     // ERROR
00048     else
00049         return -1;
00050 }
00051 
00052 void ff_h261_encode_picture_header(MpegEncContext * s, int picture_number){
00053     H261Context * h = (H261Context *) s;
00054     int format, temp_ref;
00055 
00056     avpriv_align_put_bits(&s->pb);
00057 
00058     /* Update the pointer to last GOB */
00059     s->ptr_lastgob = put_bits_ptr(&s->pb);
00060 
00061     put_bits(&s->pb, 20, 0x10); /* PSC */
00062 
00063     temp_ref= s->picture_number * (int64_t)30000 * s->avctx->time_base.num /
00064                          (1001 * (int64_t)s->avctx->time_base.den); //FIXME maybe this should use a timestamp
00065     put_sbits(&s->pb, 5, temp_ref); /* TemporalReference */
00066 
00067     put_bits(&s->pb, 1, 0); /* split screen off */
00068     put_bits(&s->pb, 1, 0); /* camera  off */
00069     put_bits(&s->pb, 1, 0); /* freeze picture release off */
00070 
00071     format = ff_h261_get_picture_format(s->width, s->height);
00072 
00073     put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
00074 
00075     put_bits(&s->pb, 1, 0); /* still image mode */
00076     put_bits(&s->pb, 1, 0); /* reserved */
00077 
00078     put_bits(&s->pb, 1, 0); /* no PEI */
00079     if(format == 0)
00080         h->gob_number = -1;
00081     else
00082         h->gob_number = 0;
00083     h->current_mba = 0;
00084 }
00085 
00089 static void h261_encode_gob_header(MpegEncContext * s, int mb_line){
00090     H261Context * h = (H261Context *)s;
00091     if(ff_h261_get_picture_format(s->width, s->height) == 0){
00092         h->gob_number+=2; // QCIF
00093     }
00094     else{
00095         h->gob_number++; // CIF
00096     }
00097     put_bits(&s->pb, 16, 1); /* GBSC */
00098     put_bits(&s->pb, 4, h->gob_number); /* GN */
00099     put_bits(&s->pb, 5, s->qscale); /* GQUANT */
00100     put_bits(&s->pb, 1, 0); /* no GEI */
00101     h->current_mba = 0;
00102     h->previous_mba = 0;
00103     h->current_mv_x=0;
00104     h->current_mv_y=0;
00105 }
00106 
00107 void ff_h261_reorder_mb_index(MpegEncContext* s){
00108     int index= s->mb_x + s->mb_y*s->mb_width;
00109 
00110     if(index % 33 == 0)
00111         h261_encode_gob_header(s,0);
00112 
00113     /* for CIF the GOB's are fragmented in the middle of a scanline
00114        that's why we need to adjust the x and y index of the macroblocks */
00115     if(ff_h261_get_picture_format(s->width,s->height) == 1){ // CIF
00116         s->mb_x =     index % 11 ; index /= 11;
00117         s->mb_y =     index %  3 ; index /=  3;
00118         s->mb_x+= 11*(index %  2); index /=  2;
00119         s->mb_y+=  3*index;
00120 
00121         ff_init_block_index(s);
00122         ff_update_block_index(s);
00123     }
00124 }
00125 
00126 static void h261_encode_motion(H261Context * h, int val){
00127     MpegEncContext * const s = &h->s;
00128     int sign, code;
00129     if(val==0){
00130         code = 0;
00131         put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
00132     }
00133     else{
00134         if(val > 15)
00135             val -=32;
00136         if(val < -16)
00137             val+=32;
00138         sign = val < 0;
00139         code = sign ? -val : val;
00140         put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
00141         put_bits(&s->pb,1,sign);
00142     }
00143 }
00144 
00145 static inline int get_cbp(MpegEncContext * s,
00146                       DCTELEM block[6][64])
00147 {
00148     int i, cbp;
00149     cbp= 0;
00150     for (i = 0; i < 6; i++) {
00151         if (s->block_last_index[i] >= 0)
00152             cbp |= 1 << (5 - i);
00153     }
00154     return cbp;
00155 }
00156 void ff_h261_encode_mb(MpegEncContext * s,
00157          DCTELEM block[6][64],
00158          int motion_x, int motion_y)
00159 {
00160     H261Context * h = (H261Context *)s;
00161     int mvd, mv_diff_x, mv_diff_y, i, cbp;
00162     cbp = 63; // avoid warning
00163     mvd = 0;
00164 
00165     h->current_mba++;
00166     h->mtype = 0;
00167 
00168     if (!s->mb_intra){
00169         /* compute cbp */
00170         cbp= get_cbp(s, block);
00171 
00172         /* mvd indicates if this block is motion compensated */
00173         mvd = motion_x | motion_y;
00174 
00175         if((cbp | mvd | s->dquant ) == 0) {
00176             /* skip macroblock */
00177             s->skip_count++;
00178             h->current_mv_x=0;
00179             h->current_mv_y=0;
00180             return;
00181         }
00182     }
00183 
00184     /* MB is not skipped, encode MBA */
00185     put_bits(&s->pb, h261_mba_bits[(h->current_mba-h->previous_mba)-1], h261_mba_code[(h->current_mba-h->previous_mba)-1]);
00186 
00187     /* calculate MTYPE */
00188     if(!s->mb_intra){
00189         h->mtype++;
00190 
00191         if(mvd || s->loop_filter)
00192             h->mtype+=3;
00193         if(s->loop_filter)
00194             h->mtype+=3;
00195         if(cbp || s->dquant)
00196             h->mtype++;
00197         assert(h->mtype > 1);
00198     }
00199 
00200     if(s->dquant)
00201         h->mtype++;
00202 
00203     put_bits(&s->pb, h261_mtype_bits[h->mtype], h261_mtype_code[h->mtype]);
00204 
00205     h->mtype = h261_mtype_map[h->mtype];
00206 
00207     if(IS_QUANT(h->mtype)){
00208         ff_set_qscale(s,s->qscale+s->dquant);
00209         put_bits(&s->pb, 5, s->qscale);
00210     }
00211 
00212     if(IS_16X16(h->mtype)){
00213         mv_diff_x = (motion_x >> 1) - h->current_mv_x;
00214         mv_diff_y = (motion_y >> 1) - h->current_mv_y;
00215         h->current_mv_x = (motion_x >> 1);
00216         h->current_mv_y = (motion_y >> 1);
00217         h261_encode_motion(h,mv_diff_x);
00218         h261_encode_motion(h,mv_diff_y);
00219     }
00220 
00221     h->previous_mba = h->current_mba;
00222 
00223     if(HAS_CBP(h->mtype)){
00224         assert(cbp>0);
00225         put_bits(&s->pb,h261_cbp_tab[cbp-1][1],h261_cbp_tab[cbp-1][0]);
00226     }
00227     for(i=0; i<6; i++) {
00228         /* encode each block */
00229         h261_encode_block(h, block[i], i);
00230     }
00231 
00232     if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
00233         h->current_mv_x=0;
00234         h->current_mv_y=0;
00235     }
00236 }
00237 
00238 void ff_h261_encode_init(MpegEncContext *s){
00239     static int done = 0;
00240 
00241     if (!done) {
00242         done = 1;
00243         init_rl(&h261_rl_tcoeff, ff_h261_rl_table_store);
00244     }
00245 
00246     s->min_qcoeff= -127;
00247     s->max_qcoeff=  127;
00248     s->y_dc_scale_table=
00249     s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
00250 }
00251 
00252 
00258 static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
00259     MpegEncContext * const s = &h->s;
00260     int level, run, i, j, last_index, last_non_zero, sign, slevel, code;
00261     RLTable *rl;
00262 
00263     rl = &h261_rl_tcoeff;
00264     if (s->mb_intra) {
00265         /* DC coef */
00266         level = block[0];
00267         /* 255 cannot be represented, so we clamp */
00268         if (level > 254) {
00269             level = 254;
00270             block[0] = 254;
00271         }
00272         /* 0 cannot be represented also */
00273         else if (level < 1) {
00274             level = 1;
00275             block[0] = 1;
00276         }
00277         if (level == 128)
00278             put_bits(&s->pb, 8, 0xff);
00279         else
00280             put_bits(&s->pb, 8, level);
00281         i = 1;
00282     } else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
00283         //special case
00284         put_bits(&s->pb,2,block[0]>0 ? 2 : 3 );
00285         i = 1;
00286     } else {
00287         i = 0;
00288     }
00289 
00290     /* AC coefs */
00291     last_index = s->block_last_index[n];
00292     last_non_zero = i - 1;
00293     for (; i <= last_index; i++) {
00294         j = s->intra_scantable.permutated[i];
00295         level = block[j];
00296         if (level) {
00297             run = i - last_non_zero - 1;
00298             sign = 0;
00299             slevel = level;
00300             if (level < 0) {
00301                 sign = 1;
00302                 level = -level;
00303             }
00304             code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level);
00305             if(run==0 && level < 16)
00306             code+=1;
00307             put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
00308             if (code == rl->n) {
00309                 put_bits(&s->pb, 6, run);
00310                 assert(slevel != 0);
00311                 assert(level <= 127);
00312                 put_sbits(&s->pb, 8, slevel);
00313             } else {
00314                 put_bits(&s->pb, 1, sign);
00315             }
00316             last_non_zero = i;
00317         }
00318     }
00319     if(last_index > -1){
00320         put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]);// END OF BLOCK
00321     }
00322 }
00323 
00324 AVCodec ff_h261_encoder = {
00325     .name           = "h261",
00326     .type           = AVMEDIA_TYPE_VIDEO,
00327     .id             = CODEC_ID_H261,
00328     .priv_data_size = sizeof(H261Context),
00329     .init           = MPV_encode_init,
00330     .encode         = MPV_encode_picture,
00331     .close          = MPV_encode_end,
00332     .pix_fmts= (const enum PixelFormat[]){PIX_FMT_YUV420P, PIX_FMT_NONE},
00333     .long_name= NULL_IF_CONFIG_SMALL("H.261"),
00334 };
00335