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 "h261.h"
00032 #include "h261data.h"
00033 
00034 extern uint8_t ff_h261_rl_table_store[2][2*MAX_RUN + MAX_LEVEL + 3];
00035 
00036 static void h261_encode_block(H261Context * h, DCTELEM * block,
00037                               int n);
00038 
00039 int ff_h261_get_picture_format(int width, int height){
00040     // QCIF
00041     if (width == 176 && height == 144)
00042         return 0;
00043     // CIF
00044     else if (width == 352 && height == 288)
00045         return 1;
00046     // ERROR
00047     else
00048         return -1;
00049 }
00050 
00051 void ff_h261_encode_picture_header(MpegEncContext * s, int picture_number){
00052     H261Context * h = (H261Context *) s;
00053     int format, temp_ref;
00054 
00055     align_put_bits(&s->pb);
00056 
00057     /* Update the pointer to last GOB */
00058     s->ptr_lastgob = pbBufPtr(&s->pb);
00059 
00060     put_bits(&s->pb, 20, 0x10); /* PSC */
00061 
00062     temp_ref= s->picture_number * (int64_t)30000 * s->avctx->time_base.num /
00063                          (1001 * (int64_t)s->avctx->time_base.den); //FIXME maybe this should use a timestamp
00064     put_sbits(&s->pb, 5, temp_ref); /* TemporalReference */
00065 
00066     put_bits(&s->pb, 1, 0); /* split screen off */
00067     put_bits(&s->pb, 1, 0); /* camera  off */
00068     put_bits(&s->pb, 1, 0); /* freeze picture release off */
00069 
00070     format = ff_h261_get_picture_format(s->width, s->height);
00071 
00072     put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
00073 
00074     put_bits(&s->pb, 1, 0); /* still image mode */
00075     put_bits(&s->pb, 1, 0); /* reserved */
00076 
00077     put_bits(&s->pb, 1, 0); /* no PEI */
00078     if(format == 0)
00079         h->gob_number = -1;
00080     else
00081         h->gob_number = 0;
00082     h->current_mba = 0;
00083 }
00084 
00088 static void h261_encode_gob_header(MpegEncContext * s, int mb_line){
00089     H261Context * h = (H261Context *)s;
00090     if(ff_h261_get_picture_format(s->width, s->height) == 0){
00091         h->gob_number+=2; // QCIF
00092     }
00093     else{
00094         h->gob_number++; // CIF
00095     }
00096     put_bits(&s->pb, 16, 1); /* GBSC */
00097     put_bits(&s->pb, 4, h->gob_number); /* GN */
00098     put_bits(&s->pb, 5, s->qscale); /* GQUANT */
00099     put_bits(&s->pb, 1, 0); /* no GEI */
00100     h->current_mba = 0;
00101     h->previous_mba = 0;
00102     h->current_mv_x=0;
00103     h->current_mv_y=0;
00104 }
00105 
00106 void ff_h261_reorder_mb_index(MpegEncContext* s){
00107     int index= s->mb_x + s->mb_y*s->mb_width;
00108 
00109     if(index % 33 == 0)
00110         h261_encode_gob_header(s,0);
00111 
00112     /* for CIF the GOB's are fragmented in the middle of a scanline
00113        that's why we need to adjust the x and y index of the macroblocks */
00114     if(ff_h261_get_picture_format(s->width,s->height) == 1){ // CIF
00115         s->mb_x =     index % 11 ; index /= 11;
00116         s->mb_y =     index %  3 ; index /=  3;
00117         s->mb_x+= 11*(index %  2); index /=  2;
00118         s->mb_y+=  3*index;
00119 
00120         ff_init_block_index(s);
00121         ff_update_block_index(s);
00122     }
00123 }
00124 
00125 static void h261_encode_motion(H261Context * h, int val){
00126     MpegEncContext * const s = &h->s;
00127     int sign, code;
00128     if(val==0){
00129         code = 0;
00130         put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
00131     }
00132     else{
00133         if(val > 15)
00134             val -=32;
00135         if(val < -16)
00136             val+=32;
00137         sign = val < 0;
00138         code = sign ? -val : val;
00139         put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
00140         put_bits(&s->pb,1,sign);
00141     }
00142 }
00143 
00144 static inline int get_cbp(MpegEncContext * s,
00145                       DCTELEM block[6][64])
00146 {
00147     int i, cbp;
00148     cbp= 0;
00149     for (i = 0; i < 6; i++) {
00150         if (s->block_last_index[i] >= 0)
00151             cbp |= 1 << (5 - i);
00152     }
00153     return cbp;
00154 }
00155 void ff_h261_encode_mb(MpegEncContext * s,
00156          DCTELEM block[6][64],
00157          int motion_x, int motion_y)
00158 {
00159     H261Context * h = (H261Context *)s;
00160     int mvd, mv_diff_x, mv_diff_y, i, cbp;
00161     cbp = 63; // avoid warning
00162     mvd = 0;
00163 
00164     h->current_mba++;
00165     h->mtype = 0;
00166 
00167     if (!s->mb_intra){
00168         /* compute cbp */
00169         cbp= get_cbp(s, block);
00170 
00171         /* mvd indicates if this block is motion compensated */
00172         mvd = motion_x | motion_y;
00173 
00174         if((cbp | mvd | s->dquant ) == 0) {
00175             /* skip macroblock */
00176             s->skip_count++;
00177             h->current_mv_x=0;
00178             h->current_mv_y=0;
00179             return;
00180         }
00181     }
00182 
00183     /* MB is not skipped, encode MBA */
00184     put_bits(&s->pb, h261_mba_bits[(h->current_mba-h->previous_mba)-1], h261_mba_code[(h->current_mba-h->previous_mba)-1]);
00185 
00186     /* calculate MTYPE */
00187     if(!s->mb_intra){
00188         h->mtype++;
00189 
00190         if(mvd || s->loop_filter)
00191             h->mtype+=3;
00192         if(s->loop_filter)
00193             h->mtype+=3;
00194         if(cbp || s->dquant)
00195             h->mtype++;
00196         assert(h->mtype > 1);
00197     }
00198 
00199     if(s->dquant)
00200         h->mtype++;
00201 
00202     put_bits(&s->pb, h261_mtype_bits[h->mtype], h261_mtype_code[h->mtype]);
00203 
00204     h->mtype = h261_mtype_map[h->mtype];
00205 
00206     if(IS_QUANT(h->mtype)){
00207         ff_set_qscale(s,s->qscale+s->dquant);
00208         put_bits(&s->pb, 5, s->qscale);
00209     }
00210 
00211     if(IS_16X16(h->mtype)){
00212         mv_diff_x = (motion_x >> 1) - h->current_mv_x;
00213         mv_diff_y = (motion_y >> 1) - h->current_mv_y;
00214         h->current_mv_x = (motion_x >> 1);
00215         h->current_mv_y = (motion_y >> 1);
00216         h261_encode_motion(h,mv_diff_x);
00217         h261_encode_motion(h,mv_diff_y);
00218     }
00219 
00220     h->previous_mba = h->current_mba;
00221 
00222     if(HAS_CBP(h->mtype)){
00223         assert(cbp>0);
00224         put_bits(&s->pb,h261_cbp_tab[cbp-1][1],h261_cbp_tab[cbp-1][0]);
00225     }
00226     for(i=0; i<6; i++) {
00227         /* encode each block */
00228         h261_encode_block(h, block[i], i);
00229     }
00230 
00231     if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
00232         h->current_mv_x=0;
00233         h->current_mv_y=0;
00234     }
00235 }
00236 
00237 void ff_h261_encode_init(MpegEncContext *s){
00238     static int done = 0;
00239 
00240     if (!done) {
00241         done = 1;
00242         init_rl(&h261_rl_tcoeff, ff_h261_rl_table_store);
00243     }
00244 
00245     s->min_qcoeff= -127;
00246     s->max_qcoeff=  127;
00247     s->y_dc_scale_table=
00248     s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
00249 }
00250 
00251 
00257 static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
00258     MpegEncContext * const s = &h->s;
00259     int level, run, last, i, j, last_index, last_non_zero, sign, slevel, code;
00260     RLTable *rl;
00261 
00262     rl = &h261_rl_tcoeff;
00263     if (s->mb_intra) {
00264         /* DC coef */
00265         level = block[0];
00266         /* 255 cannot be represented, so we clamp */
00267         if (level > 254) {
00268             level = 254;
00269             block[0] = 254;
00270         }
00271         /* 0 cannot be represented also */
00272         else if (level < 1) {
00273             level = 1;
00274             block[0] = 1;
00275         }
00276         if (level == 128)
00277             put_bits(&s->pb, 8, 0xff);
00278         else
00279             put_bits(&s->pb, 8, level);
00280         i = 1;
00281     } else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
00282         //special case
00283         put_bits(&s->pb,2,block[0]>0 ? 2 : 3 );
00284         i = 1;
00285     } else {
00286         i = 0;
00287     }
00288 
00289     /* AC coefs */
00290     last_index = s->block_last_index[n];
00291     last_non_zero = i - 1;
00292     for (; i <= last_index; i++) {
00293         j = s->intra_scantable.permutated[i];
00294         level = block[j];
00295         if (level) {
00296             run = i - last_non_zero - 1;
00297             last = (i == last_index);
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 h261_encoder = {
00325     "h261",
00326     CODEC_TYPE_VIDEO,
00327     CODEC_ID_H261,
00328     sizeof(H261Context),
00329     MPV_encode_init,
00330     MPV_encode_picture,
00331     MPV_encode_end,
00332     .pix_fmts= (enum PixelFormat[]){PIX_FMT_YUV420P, PIX_FMT_NONE},
00333     .long_name= NULL_IF_CONFIG_SMALL("H.261"),
00334 };
00335