FFmpeg: libavcodec/cavsdec.c Source File

00001 /*
00002  * Chinese AVS video (AVS1-P2, JiZhun profile) decoder.
00003  * Copyright (c) 2006  Stefan Gehrer <stefan.gehrer@gmx.de>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00028 #include "avcodec.h"
00029 #include "get_bits.h"
00030 #include "golomb.h"
00031 #include "cavs.h"
00032 
00033 static const uint8_t mv_scan[4] = {
00034     MV_FWD_X0,MV_FWD_X1,
00035     MV_FWD_X2,MV_FWD_X3
00036 };
00037 
00038 static const uint8_t cbp_tab[64][2] = {
00039   {63, 0},{15,15},{31,63},{47,31},{ 0,16},{14,32},{13,47},{11,13},
00040   { 7,14},{ 5,11},{10,12},{ 8, 5},{12,10},{61, 7},{ 4,48},{55, 3},
00041   { 1, 2},{ 2, 8},{59, 4},{ 3, 1},{62,61},{ 9,55},{ 6,59},{29,62},
00042   {45,29},{51,27},{23,23},{39,19},{27,30},{46,28},{53, 9},{30, 6},
00043   {43,60},{37,21},{60,44},{16,26},{21,51},{28,35},{19,18},{35,20},
00044   {42,24},{26,53},{44,17},{32,37},{58,39},{24,45},{20,58},{17,43},
00045   {18,42},{48,46},{22,36},{33,33},{25,34},{49,40},{40,52},{36,49},
00046   {34,50},{50,56},{52,25},{54,22},{41,54},{56,57},{38,41},{57,38}
00047 };
00048 
00049 /*****************************************************************************
00050  *
00051  * motion vector prediction
00052  *
00053  ****************************************************************************/
00054 
00055 static inline void store_mvs(AVSContext *h) {
00056     h->col_mv[h->mbidx*4 + 0] = h->mv[MV_FWD_X0];
00057     h->col_mv[h->mbidx*4 + 1] = h->mv[MV_FWD_X1];
00058     h->col_mv[h->mbidx*4 + 2] = h->mv[MV_FWD_X2];
00059     h->col_mv[h->mbidx*4 + 3] = h->mv[MV_FWD_X3];
00060 }
00061 
00062 static inline void mv_pred_direct(AVSContext *h, cavs_vector *pmv_fw,
00063                                   cavs_vector *col_mv) {
00064     cavs_vector *pmv_bw = pmv_fw + MV_BWD_OFFS;
00065     int den = h->direct_den[col_mv->ref];
00066     int m = col_mv->x >> 31;
00067 
00068     pmv_fw->dist = h->dist[1];
00069     pmv_bw->dist = h->dist[0];
00070     pmv_fw->ref = 1;
00071     pmv_bw->ref = 0;
00072     /* scale the co-located motion vector according to its temporal span */
00073     pmv_fw->x = (((den+(den*col_mv->x*pmv_fw->dist^m)-m-1)>>14)^m)-m;
00074     pmv_bw->x = m-(((den+(den*col_mv->x*pmv_bw->dist^m)-m-1)>>14)^m);
00075     m = col_mv->y >> 31;
00076     pmv_fw->y = (((den+(den*col_mv->y*pmv_fw->dist^m)-m-1)>>14)^m)-m;
00077     pmv_bw->y = m-(((den+(den*col_mv->y*pmv_bw->dist^m)-m-1)>>14)^m);
00078 }
00079 
00080 static inline void mv_pred_sym(AVSContext *h, cavs_vector *src, enum cavs_block size) {
00081     cavs_vector *dst = src + MV_BWD_OFFS;
00082 
00083     /* backward mv is the scaled and negated forward mv */
00084     dst->x = -((src->x * h->sym_factor + 256) >> 9);
00085     dst->y = -((src->y * h->sym_factor + 256) >> 9);
00086     dst->ref = 0;
00087     dst->dist = h->dist[0];
00088     set_mvs(dst, size);
00089 }
00090 
00091 /*****************************************************************************
00092  *
00093  * residual data decoding
00094  *
00095  ****************************************************************************/
00096 
00098 static inline int get_ue_code(GetBitContext *gb, int order) {
00099     if(order) {
00100         int ret = get_ue_golomb(gb) << order;
00101         return ret + get_bits(gb,order);
00102     }
00103     return get_ue_golomb(gb);
00104 }
00105 
00115 static int decode_residual_block(AVSContext *h, GetBitContext *gb,
00116                                  const struct dec_2dvlc *r, int esc_golomb_order,
00117                                  int qp, uint8_t *dst, int stride) {
00118     int i, esc_code, level, mask;
00119     unsigned int level_code, run;
00120     DCTELEM level_buf[65];
00121     uint8_t run_buf[65];
00122     DCTELEM *block = h->block;
00123 
00124     for(i=0;i<65;i++) {
00125         level_code = get_ue_code(gb,r->golomb_order);
00126         if(level_code >= ESCAPE_CODE) {
00127             run = ((level_code - ESCAPE_CODE) >> 1) + 1;
00128             if(run > 64)
00129                 return -1;
00130             esc_code = get_ue_code(gb,esc_golomb_order);
00131             level = esc_code + (run > r->max_run ? 1 : r->level_add[run]);
00132             while(level > r->inc_limit)
00133                 r++;
00134             mask = -(level_code & 1);
00135             level = (level^mask) - mask;
00136         } else {
00137             level = r->rltab[level_code][0];
00138             if(!level) //end of block signal
00139                 break;
00140             run   = r->rltab[level_code][1];
00141             r += r->rltab[level_code][2];
00142         }
00143         level_buf[i] = level;
00144         run_buf[i] = run;
00145     }
00146     if(dequant(h,level_buf, run_buf, block, ff_cavs_dequant_mul[qp],
00147                ff_cavs_dequant_shift[qp], i))
00148         return -1;
00149     h->cdsp.cavs_idct8_add(dst,block,stride);
00150     h->s.dsp.clear_block(block);
00151     return 0;
00152 }
00153 
00154 
00155 static inline void decode_residual_chroma(AVSContext *h) {
00156     if(h->cbp & (1<<4))
00157         decode_residual_block(h,&h->s.gb,ff_cavs_chroma_dec,0,
00158                               ff_cavs_chroma_qp[h->qp],h->cu,h->c_stride);
00159     if(h->cbp & (1<<5))
00160         decode_residual_block(h,&h->s.gb,ff_cavs_chroma_dec,0,
00161                               ff_cavs_chroma_qp[h->qp],h->cv,h->c_stride);
00162 }
00163 
00164 static inline int decode_residual_inter(AVSContext *h) {
00165     int block;
00166 
00167     /* get coded block pattern */
00168     int cbp= get_ue_golomb(&h->s.gb);
00169     if(cbp > 63U){
00170         av_log(h->s.avctx, AV_LOG_ERROR, "illegal inter cbp\n");
00171         return -1;
00172     }
00173     h->cbp = cbp_tab[cbp][1];
00174 
00175     /* get quantizer */
00176     if(h->cbp && !h->qp_fixed)
00177         h->qp = (h->qp + get_se_golomb(&h->s.gb)) & 63;
00178     for(block=0;block<4;block++)
00179         if(h->cbp & (1<<block))
00180             decode_residual_block(h,&h->s.gb,ff_cavs_inter_dec,0,h->qp,
00181                                   h->cy + h->luma_scan[block], h->l_stride);
00182     decode_residual_chroma(h);
00183 
00184     return 0;
00185 }
00186 
00187 /*****************************************************************************
00188  *
00189  * macroblock level
00190  *
00191  ****************************************************************************/
00192 
00193 static int decode_mb_i(AVSContext *h, int cbp_code) {
00194     GetBitContext *gb = &h->s.gb;
00195     unsigned pred_mode_uv;
00196     int block;
00197     uint8_t top[18];
00198     uint8_t *left = NULL;
00199     uint8_t *d;
00200 
00201     ff_cavs_init_mb(h);
00202 
00203     /* get intra prediction modes from stream */
00204     for(block=0;block<4;block++) {
00205         int nA,nB,predpred;
00206         int pos = ff_cavs_scan3x3[block];
00207 
00208         nA = h->pred_mode_Y[pos-1];
00209         nB = h->pred_mode_Y[pos-3];
00210         predpred = FFMIN(nA,nB);
00211         if(predpred == NOT_AVAIL) // if either is not available
00212             predpred = INTRA_L_LP;
00213         if(!get_bits1(gb)){
00214             int rem_mode= get_bits(gb, 2);
00215             predpred = rem_mode + (rem_mode >= predpred);
00216         }
00217         h->pred_mode_Y[pos] = predpred;
00218     }
00219     pred_mode_uv = get_ue_golomb(gb);
00220     if(pred_mode_uv > 6) {
00221         av_log(h->s.avctx, AV_LOG_ERROR, "illegal intra chroma pred mode\n");
00222         return -1;
00223     }
00224     ff_cavs_modify_mb_i(h, &pred_mode_uv);
00225 
00226     /* get coded block pattern */
00227     if(h->pic_type == AV_PICTURE_TYPE_I)
00228         cbp_code = get_ue_golomb(gb);
00229     if(cbp_code > 63U){
00230         av_log(h->s.avctx, AV_LOG_ERROR, "illegal intra cbp\n");
00231         return -1;
00232     }
00233     h->cbp = cbp_tab[cbp_code][0];
00234     if(h->cbp && !h->qp_fixed)
00235         h->qp = (h->qp + get_se_golomb(gb)) & 63; //qp_delta
00236 
00237     /* luma intra prediction interleaved with residual decode/transform/add */
00238     for(block=0;block<4;block++) {
00239         d = h->cy + h->luma_scan[block];
00240         ff_cavs_load_intra_pred_luma(h, top, &left, block);
00241         h->intra_pred_l[h->pred_mode_Y[ff_cavs_scan3x3[block]]]
00242             (d, top, left, h->l_stride);
00243         if(h->cbp & (1<<block))
00244             decode_residual_block(h,gb,ff_cavs_intra_dec,1,h->qp,d,h->l_stride);
00245     }
00246 
00247     /* chroma intra prediction */
00248     ff_cavs_load_intra_pred_chroma(h);
00249     h->intra_pred_c[pred_mode_uv](h->cu, &h->top_border_u[h->mbx*10],
00250                                   h->left_border_u, h->c_stride);
00251     h->intra_pred_c[pred_mode_uv](h->cv, &h->top_border_v[h->mbx*10],
00252                                   h->left_border_v, h->c_stride);
00253 
00254     decode_residual_chroma(h);
00255     ff_cavs_filter(h,I_8X8);
00256     set_mv_intra(h);
00257     return 0;
00258 }
00259 
00260 static void decode_mb_p(AVSContext *h, enum cavs_mb mb_type) {
00261     GetBitContext *gb = &h->s.gb;
00262     int ref[4];
00263 
00264     ff_cavs_init_mb(h);
00265     switch(mb_type) {
00266     case P_SKIP:
00267         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_PSKIP,  BLK_16X16, 0);
00268         break;
00269     case P_16X16:
00270         ref[0] = h->ref_flag ? 0 : get_bits1(gb);
00271         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_MEDIAN, BLK_16X16,ref[0]);
00272         break;
00273     case P_16X8:
00274         ref[0] = h->ref_flag ? 0 : get_bits1(gb);
00275         ref[2] = h->ref_flag ? 0 : get_bits1(gb);
00276         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_TOP,    BLK_16X8, ref[0]);
00277         ff_cavs_mv(h, MV_FWD_X2, MV_FWD_A1, MV_PRED_LEFT,   BLK_16X8, ref[2]);
00278         break;
00279     case P_8X16:
00280         ref[0] = h->ref_flag ? 0 : get_bits1(gb);
00281         ref[1] = h->ref_flag ? 0 : get_bits1(gb);
00282         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_B3, MV_PRED_LEFT,   BLK_8X16, ref[0]);
00283         ff_cavs_mv(h, MV_FWD_X1, MV_FWD_C2, MV_PRED_TOPRIGHT,BLK_8X16, ref[1]);
00284         break;
00285     case P_8X8:
00286         ref[0] = h->ref_flag ? 0 : get_bits1(gb);
00287         ref[1] = h->ref_flag ? 0 : get_bits1(gb);
00288         ref[2] = h->ref_flag ? 0 : get_bits1(gb);
00289         ref[3] = h->ref_flag ? 0 : get_bits1(gb);
00290         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_B3, MV_PRED_MEDIAN,   BLK_8X8, ref[0]);
00291         ff_cavs_mv(h, MV_FWD_X1, MV_FWD_C2, MV_PRED_MEDIAN,   BLK_8X8, ref[1]);
00292         ff_cavs_mv(h, MV_FWD_X2, MV_FWD_X1, MV_PRED_MEDIAN,   BLK_8X8, ref[2]);
00293         ff_cavs_mv(h, MV_FWD_X3, MV_FWD_X0, MV_PRED_MEDIAN,   BLK_8X8, ref[3]);
00294     }
00295     ff_cavs_inter(h, mb_type);
00296     set_intra_mode_default(h);
00297     store_mvs(h);
00298     if(mb_type != P_SKIP)
00299         decode_residual_inter(h);
00300     ff_cavs_filter(h,mb_type);
00301     h->col_type_base[h->mbidx] = mb_type;
00302 }
00303 
00304 static void decode_mb_b(AVSContext *h, enum cavs_mb mb_type) {
00305     int block;
00306     enum cavs_sub_mb sub_type[4];
00307     int flags;
00308 
00309     ff_cavs_init_mb(h);
00310 
00311     /* reset all MVs */
00312     h->mv[MV_FWD_X0] = ff_cavs_dir_mv;
00313     set_mvs(&h->mv[MV_FWD_X0], BLK_16X16);
00314     h->mv[MV_BWD_X0] = ff_cavs_dir_mv;
00315     set_mvs(&h->mv[MV_BWD_X0], BLK_16X16);
00316     switch(mb_type) {
00317     case B_SKIP:
00318     case B_DIRECT:
00319         if(!h->col_type_base[h->mbidx]) {
00320             /* intra MB at co-location, do in-plane prediction */
00321             ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_BSKIP, BLK_16X16, 1);
00322             ff_cavs_mv(h, MV_BWD_X0, MV_BWD_C2, MV_PRED_BSKIP, BLK_16X16, 0);
00323         } else
00324             /* direct prediction from co-located P MB, block-wise */
00325             for(block=0;block<4;block++)
00326                 mv_pred_direct(h,&h->mv[mv_scan[block]],
00327                                  &h->col_mv[h->mbidx*4 + block]);
00328         break;
00329     case B_FWD_16X16:
00330         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_MEDIAN, BLK_16X16, 1);
00331         break;
00332     case B_SYM_16X16:
00333         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_MEDIAN, BLK_16X16, 1);
00334         mv_pred_sym(h, &h->mv[MV_FWD_X0], BLK_16X16);
00335         break;
00336     case B_BWD_16X16:
00337         ff_cavs_mv(h, MV_BWD_X0, MV_BWD_C2, MV_PRED_MEDIAN, BLK_16X16, 0);
00338         break;
00339     case B_8X8:
00340         for(block=0;block<4;block++)
00341             sub_type[block] = get_bits(&h->s.gb,2);
00342         for(block=0;block<4;block++) {
00343             switch(sub_type[block]) {
00344             case B_SUB_DIRECT:
00345                 if(!h->col_type_base[h->mbidx]) {
00346                     /* intra MB at co-location, do in-plane prediction */
00347                     ff_cavs_mv(h, mv_scan[block], mv_scan[block]-3,
00348                             MV_PRED_BSKIP, BLK_8X8, 1);
00349                     ff_cavs_mv(h, mv_scan[block]+MV_BWD_OFFS,
00350                             mv_scan[block]-3+MV_BWD_OFFS,
00351                             MV_PRED_BSKIP, BLK_8X8, 0);
00352                 } else
00353                     mv_pred_direct(h,&h->mv[mv_scan[block]],
00354                                    &h->col_mv[h->mbidx*4 + block]);
00355                 break;
00356             case B_SUB_FWD:
00357                 ff_cavs_mv(h, mv_scan[block], mv_scan[block]-3,
00358                         MV_PRED_MEDIAN, BLK_8X8, 1);
00359                 break;
00360             case B_SUB_SYM:
00361                 ff_cavs_mv(h, mv_scan[block], mv_scan[block]-3,
00362                         MV_PRED_MEDIAN, BLK_8X8, 1);
00363                 mv_pred_sym(h, &h->mv[mv_scan[block]], BLK_8X8);
00364                 break;
00365             }
00366         }
00367         for(block=0;block<4;block++) {
00368             if(sub_type[block] == B_SUB_BWD)
00369                 ff_cavs_mv(h, mv_scan[block]+MV_BWD_OFFS,
00370                         mv_scan[block]+MV_BWD_OFFS-3,
00371                         MV_PRED_MEDIAN, BLK_8X8, 0);
00372         }
00373         break;
00374     default:
00375         assert((mb_type > B_SYM_16X16) && (mb_type < B_8X8));
00376         flags = ff_cavs_partition_flags[mb_type];
00377         if(mb_type & 1) { /* 16x8 macroblock types */
00378             if(flags & FWD0)
00379                 ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_TOP,  BLK_16X8, 1);
00380             if(flags & SYM0)
00381                 mv_pred_sym(h, &h->mv[MV_FWD_X0], BLK_16X8);
00382             if(flags & FWD1)
00383                 ff_cavs_mv(h, MV_FWD_X2, MV_FWD_A1, MV_PRED_LEFT, BLK_16X8, 1);
00384             if(flags & SYM1)
00385                 mv_pred_sym(h, &h->mv[MV_FWD_X2], BLK_16X8);
00386             if(flags & BWD0)
00387                 ff_cavs_mv(h, MV_BWD_X0, MV_BWD_C2, MV_PRED_TOP,  BLK_16X8, 0);
00388             if(flags & BWD1)
00389                 ff_cavs_mv(h, MV_BWD_X2, MV_BWD_A1, MV_PRED_LEFT, BLK_16X8, 0);
00390         } else {          /* 8x16 macroblock types */
00391             if(flags & FWD0)
00392                 ff_cavs_mv(h, MV_FWD_X0, MV_FWD_B3, MV_PRED_LEFT, BLK_8X16, 1);
00393             if(flags & SYM0)
00394                 mv_pred_sym(h, &h->mv[MV_FWD_X0], BLK_8X16);
00395             if(flags & FWD1)
00396                 ff_cavs_mv(h,MV_FWD_X1,MV_FWD_C2,MV_PRED_TOPRIGHT,BLK_8X16,1);
00397             if(flags & SYM1)
00398                 mv_pred_sym(h, &h->mv[MV_FWD_X1], BLK_8X16);
00399             if(flags & BWD0)
00400                 ff_cavs_mv(h, MV_BWD_X0, MV_BWD_B3, MV_PRED_LEFT, BLK_8X16, 0);
00401             if(flags & BWD1)
00402                 ff_cavs_mv(h,MV_BWD_X1,MV_BWD_C2,MV_PRED_TOPRIGHT,BLK_8X16,0);
00403         }
00404     }
00405     ff_cavs_inter(h, mb_type);
00406     set_intra_mode_default(h);
00407     if(mb_type != B_SKIP)
00408         decode_residual_inter(h);
00409     ff_cavs_filter(h,mb_type);
00410 }
00411 
00412 /*****************************************************************************
00413  *
00414  * slice level
00415  *
00416  ****************************************************************************/
00417 
00418 static inline int decode_slice_header(AVSContext *h, GetBitContext *gb) {
00419     if(h->stc > 0xAF)
00420         av_log(h->s.avctx, AV_LOG_ERROR, "unexpected start code 0x%02x\n", h->stc);
00421     h->mby = h->stc;
00422     h->mbidx = h->mby*h->mb_width;
00423 
00424     /* mark top macroblocks as unavailable */
00425     h->flags &= ~(B_AVAIL|C_AVAIL);
00426     if((h->mby == 0) && (!h->qp_fixed)){
00427         h->qp_fixed = get_bits1(gb);
00428         h->qp = get_bits(gb,6);
00429     }
00430     /* inter frame or second slice can have weighting params */
00431     if((h->pic_type != AV_PICTURE_TYPE_I) || (!h->pic_structure && h->mby >= h->mb_width/2))
00432         if(get_bits1(gb)) { //slice_weighting_flag
00433             av_log(h->s.avctx, AV_LOG_ERROR,
00434                    "weighted prediction not yet supported\n");
00435         }
00436     return 0;
00437 }
00438 
00439 static inline int check_for_slice(AVSContext *h) {
00440     GetBitContext *gb = &h->s.gb;
00441     int align;
00442 
00443     if(h->mbx)
00444         return 0;
00445     align = (-get_bits_count(gb)) & 7;
00446     /* check for stuffing byte */
00447     if(!align && (show_bits(gb,8) == 0x80))
00448         align = 8;
00449     if((show_bits_long(gb,24+align) & 0xFFFFFF) == 0x000001) {
00450         skip_bits_long(gb,24+align);
00451         h->stc = get_bits(gb,8);
00452         if (h->stc >= h->mb_height)
00453             return 0;
00454         decode_slice_header(h,gb);
00455         return 1;
00456     }
00457     return 0;
00458 }
00459 
00460 /*****************************************************************************
00461  *
00462  * frame level
00463  *
00464  ****************************************************************************/
00465 
00466 static int decode_pic(AVSContext *h) {
00467     MpegEncContext *s = &h->s;
00468     int skip_count = -1;
00469     enum cavs_mb mb_type;
00470 
00471     if (!s->context_initialized) {
00472         s->avctx->idct_algo = FF_IDCT_CAVS;
00473         if (MPV_common_init(s) < 0)
00474             return -1;
00475         ff_init_scantable(s->dsp.idct_permutation,&h->scantable,ff_zigzag_direct);
00476     }
00477     skip_bits(&s->gb,16);//bbv_dwlay
00478     if(h->stc == PIC_PB_START_CODE) {
00479         h->pic_type = get_bits(&s->gb,2) + AV_PICTURE_TYPE_I;
00480         if(h->pic_type > AV_PICTURE_TYPE_B) {
00481             av_log(s->avctx, AV_LOG_ERROR, "illegal picture type\n");
00482             return -1;
00483         }
00484         /* make sure we have the reference frames we need */
00485         if(!h->DPB[0].data[0] ||
00486           (!h->DPB[1].data[0] && h->pic_type == AV_PICTURE_TYPE_B))
00487             return -1;
00488     } else {
00489         h->pic_type = AV_PICTURE_TYPE_I;
00490         if(get_bits1(&s->gb))
00491             skip_bits(&s->gb,24);//time_code
00492         /* old sample clips were all progressive and no low_delay,
00493            bump stream revision if detected otherwise */
00494         if((s->low_delay) || !(show_bits(&s->gb,9) & 1))
00495             h->stream_revision = 1;
00496         /* similarly test top_field_first and repeat_first_field */
00497         else if(show_bits(&s->gb,11) & 3)
00498             h->stream_revision = 1;
00499         if(h->stream_revision > 0)
00500             skip_bits(&s->gb,1); //marker_bit
00501     }
00502     /* release last B frame */
00503     if(h->picture.data[0])
00504         s->avctx->release_buffer(s->avctx, (AVFrame *)&h->picture);
00505 
00506     s->avctx->get_buffer(s->avctx, (AVFrame *)&h->picture);
00507     ff_cavs_init_pic(h);
00508     h->picture.poc = get_bits(&s->gb,8)*2;
00509 
00510     /* get temporal distances and MV scaling factors */
00511     if(h->pic_type != AV_PICTURE_TYPE_B) {
00512         h->dist[0] = (h->picture.poc - h->DPB[0].poc  + 512) % 512;
00513     } else {
00514         h->dist[0] = (h->DPB[0].poc  - h->picture.poc + 512) % 512;
00515     }
00516     h->dist[1] = (h->picture.poc - h->DPB[1].poc  + 512) % 512;
00517     h->scale_den[0] = h->dist[0] ? 512/h->dist[0] : 0;
00518     h->scale_den[1] = h->dist[1] ? 512/h->dist[1] : 0;
00519     if(h->pic_type == AV_PICTURE_TYPE_B) {
00520         h->sym_factor = h->dist[0]*h->scale_den[1];
00521     } else {
00522         h->direct_den[0] = h->dist[0] ? 16384/h->dist[0] : 0;
00523         h->direct_den[1] = h->dist[1] ? 16384/h->dist[1] : 0;
00524     }
00525 
00526     if(s->low_delay)
00527         get_ue_golomb(&s->gb); //bbv_check_times
00528     h->progressive             = get_bits1(&s->gb);
00529     h->pic_structure = 1;
00530     if(!h->progressive)
00531         h->pic_structure = get_bits1(&s->gb);
00532     if(!h->pic_structure && h->stc == PIC_PB_START_CODE)
00533         skip_bits1(&s->gb);     //advanced_pred_mode_disable
00534     skip_bits1(&s->gb);        //top_field_first
00535     skip_bits1(&s->gb);        //repeat_first_field
00536     h->qp_fixed                = get_bits1(&s->gb);
00537     h->qp                      = get_bits(&s->gb,6);
00538     if(h->pic_type == AV_PICTURE_TYPE_I) {
00539         if(!h->progressive && !h->pic_structure)
00540             skip_bits1(&s->gb);//what is this?
00541         skip_bits(&s->gb,4);   //reserved bits
00542     } else {
00543         if(!(h->pic_type == AV_PICTURE_TYPE_B && h->pic_structure == 1))
00544             h->ref_flag        = get_bits1(&s->gb);
00545         skip_bits(&s->gb,4);   //reserved bits
00546         h->skip_mode_flag      = get_bits1(&s->gb);
00547     }
00548     h->loop_filter_disable     = get_bits1(&s->gb);
00549     if(!h->loop_filter_disable && get_bits1(&s->gb)) {
00550         h->alpha_offset        = get_se_golomb(&s->gb);
00551         h->beta_offset         = get_se_golomb(&s->gb);
00552     } else {
00553         h->alpha_offset = h->beta_offset  = 0;
00554     }
00555     if(h->pic_type == AV_PICTURE_TYPE_I) {
00556         do {
00557             check_for_slice(h);
00558             decode_mb_i(h, 0);
00559         } while(ff_cavs_next_mb(h));
00560     } else if(h->pic_type == AV_PICTURE_TYPE_P) {
00561         do {
00562             if(check_for_slice(h))
00563                 skip_count = -1;
00564             if(h->skip_mode_flag && (skip_count < 0))
00565                 skip_count = get_ue_golomb(&s->gb);
00566             if(h->skip_mode_flag && skip_count--) {
00567                 decode_mb_p(h,P_SKIP);
00568             } else {
00569                 mb_type = get_ue_golomb(&s->gb) + P_SKIP + h->skip_mode_flag;
00570                 if(mb_type > P_8X8)
00571                     decode_mb_i(h, mb_type - P_8X8 - 1);
00572                 else
00573                     decode_mb_p(h,mb_type);
00574             }
00575         } while(ff_cavs_next_mb(h));
00576     } else { /* AV_PICTURE_TYPE_B */
00577         do {
00578             if(check_for_slice(h))
00579                 skip_count = -1;
00580             if(h->skip_mode_flag && (skip_count < 0))
00581                 skip_count = get_ue_golomb(&s->gb);
00582             if(h->skip_mode_flag && skip_count--) {
00583                 decode_mb_b(h,B_SKIP);
00584             } else {
00585                 mb_type = get_ue_golomb(&s->gb) + B_SKIP + h->skip_mode_flag;
00586                 if(mb_type > B_8X8)
00587                     decode_mb_i(h, mb_type - B_8X8 - 1);
00588                 else
00589                     decode_mb_b(h,mb_type);
00590             }
00591         } while(ff_cavs_next_mb(h));
00592     }
00593     if(h->pic_type != AV_PICTURE_TYPE_B) {
00594         if(h->DPB[1].data[0])
00595             s->avctx->release_buffer(s->avctx, (AVFrame *)&h->DPB[1]);
00596         h->DPB[1] = h->DPB[0];
00597         h->DPB[0] = h->picture;
00598         memset(&h->picture,0,sizeof(Picture));
00599     }
00600     return 0;
00601 }
00602 
00603 /*****************************************************************************
00604  *
00605  * headers and interface
00606  *
00607  ****************************************************************************/
00608 
00609 static int decode_seq_header(AVSContext *h) {
00610     MpegEncContext *s = &h->s;
00611     int frame_rate_code;
00612 
00613     h->profile =         get_bits(&s->gb,8);
00614     h->level =           get_bits(&s->gb,8);
00615     skip_bits1(&s->gb); //progressive sequence
00616     s->width =           get_bits(&s->gb,14);
00617     s->height =          get_bits(&s->gb,14);
00618     skip_bits(&s->gb,2); //chroma format
00619     skip_bits(&s->gb,3); //sample_precision
00620     h->aspect_ratio =    get_bits(&s->gb,4);
00621     frame_rate_code =    get_bits(&s->gb,4);
00622     skip_bits(&s->gb,18);//bit_rate_lower
00623     skip_bits1(&s->gb);  //marker_bit
00624     skip_bits(&s->gb,12);//bit_rate_upper
00625     s->low_delay =       get_bits1(&s->gb);
00626     h->mb_width  = (s->width  + 15) >> 4;
00627     h->mb_height = (s->height + 15) >> 4;
00628     h->s.avctx->time_base.den = ff_frame_rate_tab[frame_rate_code].num;
00629     h->s.avctx->time_base.num = ff_frame_rate_tab[frame_rate_code].den;
00630     h->s.avctx->width  = s->width;
00631     h->s.avctx->height = s->height;
00632     if(!h->top_qp)
00633         ff_cavs_init_top_lines(h);
00634     return 0;
00635 }
00636 
00637 static void cavs_flush(AVCodecContext * avctx) {
00638     AVSContext *h = avctx->priv_data;
00639     h->got_keyframe = 0;
00640 }
00641 
00642 static int cavs_decode_frame(AVCodecContext * avctx,void *data, int *data_size,
00643                              AVPacket *avpkt) {
00644     const uint8_t *buf = avpkt->data;
00645     int buf_size = avpkt->size;
00646     AVSContext *h = avctx->priv_data;
00647     MpegEncContext *s = &h->s;
00648     int input_size;
00649     const uint8_t *buf_end;
00650     const uint8_t *buf_ptr;
00651     AVFrame *picture = data;
00652     uint32_t stc = -1;
00653 
00654     s->avctx = avctx;
00655 
00656     if (buf_size == 0) {
00657         if(!s->low_delay && h->DPB[0].data[0]) {
00658             *data_size = sizeof(AVPicture);
00659             *picture = *(AVFrame *) &h->DPB[0];
00660         }
00661         return 0;
00662     }
00663 
00664     buf_ptr = buf;
00665     buf_end = buf + buf_size;
00666     for(;;) {
00667         buf_ptr = ff_find_start_code(buf_ptr,buf_end, &stc);
00668         if((stc & 0xFFFFFE00) || buf_ptr == buf_end)
00669             return FFMAX(0, buf_ptr - buf - s->parse_context.last_index);
00670         input_size = (buf_end - buf_ptr)*8;
00671         switch(stc) {
00672         case CAVS_START_CODE:
00673             init_get_bits(&s->gb, buf_ptr, input_size);
00674             decode_seq_header(h);
00675             break;
00676         case PIC_I_START_CODE:
00677             if(!h->got_keyframe) {
00678                 if(h->DPB[0].data[0])
00679                     avctx->release_buffer(avctx, (AVFrame *)&h->DPB[0]);
00680                 if(h->DPB[1].data[0])
00681                     avctx->release_buffer(avctx, (AVFrame *)&h->DPB[1]);
00682                 h->got_keyframe = 1;
00683             }
00684         case PIC_PB_START_CODE:
00685             *data_size = 0;
00686             if(!h->got_keyframe)
00687                 break;
00688             init_get_bits(&s->gb, buf_ptr, input_size);
00689             h->stc = stc;
00690             if(decode_pic(h))
00691                 break;
00692             *data_size = sizeof(AVPicture);
00693             if(h->pic_type != AV_PICTURE_TYPE_B) {
00694                 if(h->DPB[1].data[0]) {
00695                     *picture = *(AVFrame *) &h->DPB[1];
00696                 } else {
00697                     *data_size = 0;
00698                 }
00699             } else
00700                 *picture = *(AVFrame *) &h->picture;
00701             break;
00702         case EXT_START_CODE:
00703             //mpeg_decode_extension(avctx,buf_ptr, input_size);
00704             break;
00705         case USER_START_CODE:
00706             //mpeg_decode_user_data(avctx,buf_ptr, input_size);
00707             break;
00708         default:
00709             if (stc <= SLICE_MAX_START_CODE) {
00710                 init_get_bits(&s->gb, buf_ptr, input_size);
00711                 decode_slice_header(h, &s->gb);
00712             }
00713             break;
00714         }
00715     }
00716 }
00717 
00718 AVCodec ff_cavs_decoder = {
00719     "cavs",
00720     AVMEDIA_TYPE_VIDEO,
00721     CODEC_ID_CAVS,
00722     sizeof(AVSContext),
00723     ff_cavs_init,
00724     NULL,
00725     ff_cavs_end,
00726     cavs_decode_frame,
00727     CODEC_CAP_DR1 | CODEC_CAP_DELAY,
00728     .flush= cavs_flush,
00729     .long_name= NULL_IF_CONFIG_SMALL("Chinese AVS video (AVS1-P2, JiZhun profile)"),
00730 };