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 "libavutil/avassert.h"
00029 #include "dsputil.h"
00030 #include "avcodec.h"
00031 #include "mpegvideo.h"
00032 #include "h263.h"
00033 #include "h261.h"
00034 #include "h261data.h"
00035 
00036 extern uint8_t ff_h261_rl_table_store[2][2*MAX_RUN + MAX_LEVEL + 3];
00037 
00038 static void h261_encode_block(H261Context * h, DCTELEM * block,
00039                               int n);
00040 
00041 int ff_h261_get_picture_format(int width, int height){
00042     // QCIF
00043     if (width == 176 && height == 144)
00044         return 0;
00045     // CIF
00046     else if (width == 352 && height == 288)
00047         return 1;
00048     // ERROR
00049     else
00050         return -1;
00051 }
00052 
00053 void ff_h261_encode_picture_header(MpegEncContext * s, int picture_number){
00054     H261Context * h = (H261Context *) s;
00055     int format, temp_ref;
00056 
00057     avpriv_align_put_bits(&s->pb);
00058 
00059     /* Update the pointer to last GOB */
00060     s->ptr_lastgob = put_bits_ptr(&s->pb);
00061 
00062     put_bits(&s->pb, 20, 0x10); /* PSC */
00063 
00064     temp_ref= s->picture_number * (int64_t)30000 * s->avctx->time_base.num /
00065                          (1001 * (int64_t)s->avctx->time_base.den); //FIXME maybe this should use a timestamp
00066     put_sbits(&s->pb, 5, temp_ref); /* TemporalReference */
00067 
00068     put_bits(&s->pb, 1, 0); /* split screen off */
00069     put_bits(&s->pb, 1, 0); /* camera  off */
00070     put_bits(&s->pb, 1, 0); /* freeze picture release off */
00071 
00072     format = ff_h261_get_picture_format(s->width, s->height);
00073 
00074     put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
00075 
00076     put_bits(&s->pb, 1, 0); /* still image mode */
00077     put_bits(&s->pb, 1, 0); /* reserved */
00078 
00079     put_bits(&s->pb, 1, 0); /* no PEI */
00080     if(format == 0)
00081         h->gob_number = -1;
00082     else
00083         h->gob_number = 0;
00084     h->current_mba = 0;
00085 }
00086 
00090 static void h261_encode_gob_header(MpegEncContext * s, int mb_line){
00091     H261Context * h = (H261Context *)s;
00092     if(ff_h261_get_picture_format(s->width, s->height) == 0){
00093         h->gob_number+=2; // QCIF
00094     }
00095     else{
00096         h->gob_number++; // CIF
00097     }
00098     put_bits(&s->pb, 16, 1); /* GBSC */
00099     put_bits(&s->pb, 4, h->gob_number); /* GN */
00100     put_bits(&s->pb, 5, s->qscale); /* GQUANT */
00101     put_bits(&s->pb, 1, 0); /* no GEI */
00102     h->current_mba = 0;
00103     h->previous_mba = 0;
00104     h->current_mv_x=0;
00105     h->current_mv_y=0;
00106 }
00107 
00108 void ff_h261_reorder_mb_index(MpegEncContext* s){
00109     int index= s->mb_x + s->mb_y*s->mb_width;
00110 
00111     if(index % 33 == 0)
00112         h261_encode_gob_header(s,0);
00113 
00114     /* for CIF the GOB's are fragmented in the middle of a scanline
00115        that's why we need to adjust the x and y index of the macroblocks */
00116     if(ff_h261_get_picture_format(s->width,s->height) == 1){ // CIF
00117         s->mb_x =     index % 11 ; index /= 11;
00118         s->mb_y =     index %  3 ; index /=  3;
00119         s->mb_x+= 11*(index %  2); index /=  2;
00120         s->mb_y+=  3*index;
00121 
00122         ff_init_block_index(s);
00123         ff_update_block_index(s);
00124     }
00125 }
00126 
00127 static void h261_encode_motion(H261Context * h, int val){
00128     MpegEncContext * const s = &h->s;
00129     int sign, code;
00130     if(val==0){
00131         code = 0;
00132         put_bits(&s->pb,ff_h261_mv_tab[code][1],ff_h261_mv_tab[code][0]);
00133     }
00134     else{
00135         if(val > 15)
00136             val -=32;
00137         if(val < -16)
00138             val+=32;
00139         sign = val < 0;
00140         code = sign ? -val : val;
00141         put_bits(&s->pb,ff_h261_mv_tab[code][1],ff_h261_mv_tab[code][0]);
00142         put_bits(&s->pb,1,sign);
00143     }
00144 }
00145 
00146 static inline int get_cbp(MpegEncContext * s,
00147                       DCTELEM block[6][64])
00148 {
00149     int i, cbp;
00150     cbp= 0;
00151     for (i = 0; i < 6; i++) {
00152         if (s->block_last_index[i] >= 0)
00153             cbp |= 1 << (5 - i);
00154     }
00155     return cbp;
00156 }
00157 void ff_h261_encode_mb(MpegEncContext * s,
00158          DCTELEM block[6][64],
00159          int motion_x, int motion_y)
00160 {
00161     H261Context * h = (H261Context *)s;
00162     int mvd, mv_diff_x, mv_diff_y, i, cbp;
00163     cbp = 63; // avoid warning
00164     mvd = 0;
00165 
00166     h->current_mba++;
00167     h->mtype = 0;
00168 
00169     if (!s->mb_intra){
00170         /* compute cbp */
00171         cbp= get_cbp(s, block);
00172 
00173         /* mvd indicates if this block is motion compensated */
00174         mvd = motion_x | motion_y;
00175 
00176         if((cbp | mvd | s->dquant ) == 0) {
00177             /* skip macroblock */
00178             s->skip_count++;
00179             h->current_mv_x=0;
00180             h->current_mv_y=0;
00181             return;
00182         }
00183     }
00184 
00185     /* MB is not skipped, encode MBA */
00186     put_bits(&s->pb, ff_h261_mba_bits[(h->current_mba-h->previous_mba)-1], ff_h261_mba_code[(h->current_mba-h->previous_mba)-1]);
00187 
00188     /* calculate MTYPE */
00189     if(!s->mb_intra){
00190         h->mtype++;
00191 
00192         if(mvd || s->loop_filter)
00193             h->mtype+=3;
00194         if(s->loop_filter)
00195             h->mtype+=3;
00196         if(cbp || s->dquant)
00197             h->mtype++;
00198         av_assert1(h->mtype > 1);
00199     }
00200 
00201     if(s->dquant)
00202         h->mtype++;
00203 
00204     put_bits(&s->pb, ff_h261_mtype_bits[h->mtype], ff_h261_mtype_code[h->mtype]);
00205 
00206     h->mtype = ff_h261_mtype_map[h->mtype];
00207 
00208     if(IS_QUANT(h->mtype)){
00209         ff_set_qscale(s,s->qscale+s->dquant);
00210         put_bits(&s->pb, 5, s->qscale);
00211     }
00212 
00213     if(IS_16X16(h->mtype)){
00214         mv_diff_x = (motion_x >> 1) - h->current_mv_x;
00215         mv_diff_y = (motion_y >> 1) - h->current_mv_y;
00216         h->current_mv_x = (motion_x >> 1);
00217         h->current_mv_y = (motion_y >> 1);
00218         h261_encode_motion(h,mv_diff_x);
00219         h261_encode_motion(h,mv_diff_y);
00220     }
00221 
00222     h->previous_mba = h->current_mba;
00223 
00224     if(HAS_CBP(h->mtype)){
00225         av_assert1(cbp>0);
00226         put_bits(&s->pb,ff_h261_cbp_tab[cbp-1][1],ff_h261_cbp_tab[cbp-1][0]);
00227     }
00228     for(i=0; i<6; i++) {
00229         /* encode each block */
00230         h261_encode_block(h, block[i], i);
00231     }
00232 
00233     if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
00234         h->current_mv_x=0;
00235         h->current_mv_y=0;
00236     }
00237 }
00238 
00239 void ff_h261_encode_init(MpegEncContext *s){
00240     static int done = 0;
00241 
00242     if (!done) {
00243         done = 1;
00244         ff_init_rl(&ff_h261_rl_tcoeff, ff_h261_rl_table_store);
00245     }
00246 
00247     s->min_qcoeff= -127;
00248     s->max_qcoeff=  127;
00249     s->y_dc_scale_table=
00250     s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
00251 }
00252 
00253 
00259 static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
00260     MpegEncContext * const s = &h->s;
00261     int level, run, i, j, last_index, last_non_zero, sign, slevel, code;
00262     RLTable *rl;
00263 
00264     rl = &ff_h261_rl_tcoeff;
00265     if (s->mb_intra) {
00266         /* DC coef */
00267         level = block[0];
00268         /* 255 cannot be represented, so we clamp */
00269         if (level > 254) {
00270             level = 254;
00271             block[0] = 254;
00272         }
00273         /* 0 cannot be represented also */
00274         else if (level < 1) {
00275             level = 1;
00276             block[0] = 1;
00277         }
00278         if (level == 128)
00279             put_bits(&s->pb, 8, 0xff);
00280         else
00281             put_bits(&s->pb, 8, level);
00282         i = 1;
00283     } else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
00284         //special case
00285         put_bits(&s->pb,2,block[0]>0 ? 2 : 3 );
00286         i = 1;
00287     } else {
00288         i = 0;
00289     }
00290 
00291     /* AC coefs */
00292     last_index = s->block_last_index[n];
00293     last_non_zero = i - 1;
00294     for (; i <= last_index; i++) {
00295         j = s->intra_scantable.permutated[i];
00296         level = block[j];
00297         if (level) {
00298             run = i - last_non_zero - 1;
00299             sign = 0;
00300             slevel = level;
00301             if (level < 0) {
00302                 sign = 1;
00303                 level = -level;
00304             }
00305             code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level);
00306             if(run==0 && level < 16)
00307             code+=1;
00308             put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
00309             if (code == rl->n) {
00310                 put_bits(&s->pb, 6, run);
00311                 av_assert1(slevel != 0);
00312                 av_assert1(level <= 127);
00313                 put_sbits(&s->pb, 8, slevel);
00314             } else {
00315                 put_bits(&s->pb, 1, sign);
00316             }
00317             last_non_zero = i;
00318         }
00319     }
00320     if(last_index > -1){
00321         put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]);// END OF BLOCK
00322     }
00323 }
00324 
00325 FF_MPV_GENERIC_CLASS(h261)
00326 
00327 AVCodec ff_h261_encoder = {
00328     .name           = "h261",
00329     .type           = AVMEDIA_TYPE_VIDEO,
00330     .id             = AV_CODEC_ID_H261,
00331     .priv_data_size = sizeof(H261Context),
00332     .init           = ff_MPV_encode_init,
00333     .encode2        = ff_MPV_encode_picture,
00334     .close          = ff_MPV_encode_end,
00335     .pix_fmts       = (const enum PixelFormat[]){ PIX_FMT_YUV420P, PIX_FMT_NONE },
00336     .long_name      = NULL_IF_CONFIG_SMALL("H.261"),
00337     .priv_class     = &h261_class,
00338 };