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libavcodec/snowdec.c

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00001 /*
00002  * Copyright (C) 2004 Michael Niedermayer <michaelni@gmx.at>
00003  *
00004  * This file is part of Libav.
00005  *
00006  * Libav is free software; you can redistribute it and/or
00007  * modify it under the terms of the GNU Lesser General Public
00008  * License as published by the Free Software Foundation; either
00009  * version 2.1 of the License, or (at your option) any later version.
00010  *
00011  * Libav is distributed in the hope that it will be useful,
00012  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014  * Lesser General Public License for more details.
00015  *
00016  * You should have received a copy of the GNU Lesser General Public
00017  * License along with Libav; if not, write to the Free Software
00018  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00019  */
00020 
00021 #include "libavutil/intmath.h"
00022 #include "libavutil/log.h"
00023 #include "libavutil/opt.h"
00024 #include "avcodec.h"
00025 #include "dsputil.h"
00026 #include "dwt.h"
00027 #include "snow.h"
00028 
00029 #include "rangecoder.h"
00030 #include "mathops.h"
00031 
00032 #include "mpegvideo.h"
00033 #include "h263.h"
00034 
00035 #undef NDEBUG
00036 #include <assert.h>
00037 
00038 static av_always_inline void predict_slice_buffered(SnowContext *s, slice_buffer * sb, IDWTELEM * old_buffer, int plane_index, int add, int mb_y){
00039     Plane *p= &s->plane[plane_index];
00040     const int mb_w= s->b_width  << s->block_max_depth;
00041     const int mb_h= s->b_height << s->block_max_depth;
00042     int x, y, mb_x;
00043     int block_size = MB_SIZE >> s->block_max_depth;
00044     int block_w    = plane_index ? block_size/2 : block_size;
00045     const uint8_t *obmc  = plane_index ? obmc_tab[s->block_max_depth+1] : obmc_tab[s->block_max_depth];
00046     int obmc_stride= plane_index ? block_size : 2*block_size;
00047     int ref_stride= s->current_picture.linesize[plane_index];
00048     uint8_t *dst8= s->current_picture.data[plane_index];
00049     int w= p->width;
00050     int h= p->height;
00051 
00052     if(s->keyframe || (s->avctx->debug&512)){
00053         if(mb_y==mb_h)
00054             return;
00055 
00056         if(add){
00057             for(y=block_w*mb_y; y<FFMIN(h,block_w*(mb_y+1)); y++){
00058 //                DWTELEM * line = slice_buffer_get_line(sb, y);
00059                 IDWTELEM * line = sb->line[y];
00060                 for(x=0; x<w; x++){
00061 //                    int v= buf[x + y*w] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
00062                     int v= line[x] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
00063                     v >>= FRAC_BITS;
00064                     if(v&(~255)) v= ~(v>>31);
00065                     dst8[x + y*ref_stride]= v;
00066                 }
00067             }
00068         }else{
00069             for(y=block_w*mb_y; y<FFMIN(h,block_w*(mb_y+1)); y++){
00070 //                DWTELEM * line = slice_buffer_get_line(sb, y);
00071                 IDWTELEM * line = sb->line[y];
00072                 for(x=0; x<w; x++){
00073                     line[x] -= 128 << FRAC_BITS;
00074 //                    buf[x + y*w]-= 128<<FRAC_BITS;
00075                 }
00076             }
00077         }
00078 
00079         return;
00080     }
00081 
00082     for(mb_x=0; mb_x<=mb_w; mb_x++){
00083         add_yblock(s, 1, sb, old_buffer, dst8, obmc,
00084                    block_w*mb_x - block_w/2,
00085                    block_w*mb_y - block_w/2,
00086                    block_w, block_w,
00087                    w, h,
00088                    w, ref_stride, obmc_stride,
00089                    mb_x - 1, mb_y - 1,
00090                    add, 0, plane_index);
00091     }
00092 }
00093 
00094 static inline void decode_subband_slice_buffered(SnowContext *s, SubBand *b, slice_buffer * sb, int start_y, int h, int save_state[1]){
00095     const int w= b->width;
00096     int y;
00097     const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
00098     int qmul= qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
00099     int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
00100     int new_index = 0;
00101 
00102     if(b->ibuf == s->spatial_idwt_buffer || s->qlog == LOSSLESS_QLOG){
00103         qadd= 0;
00104         qmul= 1<<QEXPSHIFT;
00105     }
00106 
00107     /* If we are on the second or later slice, restore our index. */
00108     if (start_y != 0)
00109         new_index = save_state[0];
00110 
00111 
00112     for(y=start_y; y<h; y++){
00113         int x = 0;
00114         int v;
00115         IDWTELEM * line = slice_buffer_get_line(sb, y * b->stride_line + b->buf_y_offset) + b->buf_x_offset;
00116         memset(line, 0, b->width*sizeof(IDWTELEM));
00117         v = b->x_coeff[new_index].coeff;
00118         x = b->x_coeff[new_index++].x;
00119         while(x < w){
00120             register int t= ( (v>>1)*qmul + qadd)>>QEXPSHIFT;
00121             register int u= -(v&1);
00122             line[x] = (t^u) - u;
00123 
00124             v = b->x_coeff[new_index].coeff;
00125             x = b->x_coeff[new_index++].x;
00126         }
00127     }
00128 
00129     /* Save our variables for the next slice. */
00130     save_state[0] = new_index;
00131 
00132     return;
00133 }
00134 
00135 static void decode_q_branch(SnowContext *s, int level, int x, int y){
00136     const int w= s->b_width << s->block_max_depth;
00137     const int rem_depth= s->block_max_depth - level;
00138     const int index= (x + y*w) << rem_depth;
00139     int trx= (x+1)<<rem_depth;
00140     const BlockNode *left  = x ? &s->block[index-1] : &null_block;
00141     const BlockNode *top   = y ? &s->block[index-w] : &null_block;
00142     const BlockNode *tl    = y && x ? &s->block[index-w-1] : left;
00143     const BlockNode *tr    = y && trx<w && ((x&1)==0 || level==0) ? &s->block[index-w+(1<<rem_depth)] : tl; //FIXME use lt
00144     int s_context= 2*left->level + 2*top->level + tl->level + tr->level;
00145 
00146     if(s->keyframe){
00147         set_blocks(s, level, x, y, null_block.color[0], null_block.color[1], null_block.color[2], null_block.mx, null_block.my, null_block.ref, BLOCK_INTRA);
00148         return;
00149     }
00150 
00151     if(level==s->block_max_depth || get_rac(&s->c, &s->block_state[4 + s_context])){
00152         int type, mx, my;
00153         int l = left->color[0];
00154         int cb= left->color[1];
00155         int cr= left->color[2];
00156         int ref = 0;
00157         int ref_context= av_log2(2*left->ref) + av_log2(2*top->ref);
00158         int mx_context= av_log2(2*FFABS(left->mx - top->mx)) + 0*av_log2(2*FFABS(tr->mx - top->mx));
00159         int my_context= av_log2(2*FFABS(left->my - top->my)) + 0*av_log2(2*FFABS(tr->my - top->my));
00160 
00161         type= get_rac(&s->c, &s->block_state[1 + left->type + top->type]) ? BLOCK_INTRA : 0;
00162 
00163         if(type){
00164             pred_mv(s, &mx, &my, 0, left, top, tr);
00165             l += get_symbol(&s->c, &s->block_state[32], 1);
00166             cb+= get_symbol(&s->c, &s->block_state[64], 1);
00167             cr+= get_symbol(&s->c, &s->block_state[96], 1);
00168         }else{
00169             if(s->ref_frames > 1)
00170                 ref= get_symbol(&s->c, &s->block_state[128 + 1024 + 32*ref_context], 0);
00171             pred_mv(s, &mx, &my, ref, left, top, tr);
00172             mx+= get_symbol(&s->c, &s->block_state[128 + 32*(mx_context + 16*!!ref)], 1);
00173             my+= get_symbol(&s->c, &s->block_state[128 + 32*(my_context + 16*!!ref)], 1);
00174         }
00175         set_blocks(s, level, x, y, l, cb, cr, mx, my, ref, type);
00176     }else{
00177         decode_q_branch(s, level+1, 2*x+0, 2*y+0);
00178         decode_q_branch(s, level+1, 2*x+1, 2*y+0);
00179         decode_q_branch(s, level+1, 2*x+0, 2*y+1);
00180         decode_q_branch(s, level+1, 2*x+1, 2*y+1);
00181     }
00182 }
00183 
00184 static void dequantize_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int start_y, int end_y){
00185     const int w= b->width;
00186     const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
00187     const int qmul= qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
00188     const int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
00189     int x,y;
00190 
00191     if(s->qlog == LOSSLESS_QLOG) return;
00192 
00193     for(y=start_y; y<end_y; y++){
00194 //        DWTELEM * line = slice_buffer_get_line_from_address(sb, src + (y * stride));
00195         IDWTELEM * line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
00196         for(x=0; x<w; x++){
00197             int i= line[x];
00198             if(i<0){
00199                 line[x]= -((-i*qmul + qadd)>>(QEXPSHIFT)); //FIXME try different bias
00200             }else if(i>0){
00201                 line[x]=  (( i*qmul + qadd)>>(QEXPSHIFT));
00202             }
00203         }
00204     }
00205 }
00206 
00207 static void correlate_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int inverse, int use_median, int start_y, int end_y){
00208     const int w= b->width;
00209     int x,y;
00210 
00211     IDWTELEM * line=0; // silence silly "could be used without having been initialized" warning
00212     IDWTELEM * prev;
00213 
00214     if (start_y != 0)
00215         line = slice_buffer_get_line(sb, ((start_y - 1) * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
00216 
00217     for(y=start_y; y<end_y; y++){
00218         prev = line;
00219 //        line = slice_buffer_get_line_from_address(sb, src + (y * stride));
00220         line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
00221         for(x=0; x<w; x++){
00222             if(x){
00223                 if(use_median){
00224                     if(y && x+1<w) line[x] += mid_pred(line[x - 1], prev[x], prev[x + 1]);
00225                     else  line[x] += line[x - 1];
00226                 }else{
00227                     if(y) line[x] += mid_pred(line[x - 1], prev[x], line[x - 1] + prev[x] - prev[x - 1]);
00228                     else  line[x] += line[x - 1];
00229                 }
00230             }else{
00231                 if(y) line[x] += prev[x];
00232             }
00233         }
00234     }
00235 }
00236 
00237 static void decode_qlogs(SnowContext *s){
00238     int plane_index, level, orientation;
00239 
00240     for(plane_index=0; plane_index<3; plane_index++){
00241         for(level=0; level<s->spatial_decomposition_count; level++){
00242             for(orientation=level ? 1:0; orientation<4; orientation++){
00243                 int q;
00244                 if     (plane_index==2) q= s->plane[1].band[level][orientation].qlog;
00245                 else if(orientation==2) q= s->plane[plane_index].band[level][1].qlog;
00246                 else                    q= get_symbol(&s->c, s->header_state, 1);
00247                 s->plane[plane_index].band[level][orientation].qlog= q;
00248             }
00249         }
00250     }
00251 }
00252 
00253 #define GET_S(dst, check) \
00254     tmp= get_symbol(&s->c, s->header_state, 0);\
00255     if(!(check)){\
00256         av_log(s->avctx, AV_LOG_ERROR, "Error " #dst " is %d\n", tmp);\
00257         return -1;\
00258     }\
00259     dst= tmp;
00260 
00261 static int decode_header(SnowContext *s){
00262     int plane_index, tmp;
00263     uint8_t kstate[32];
00264 
00265     memset(kstate, MID_STATE, sizeof(kstate));
00266 
00267     s->keyframe= get_rac(&s->c, kstate);
00268     if(s->keyframe || s->always_reset){
00269         ff_snow_reset_contexts(s);
00270         s->spatial_decomposition_type=
00271         s->qlog=
00272         s->qbias=
00273         s->mv_scale=
00274         s->block_max_depth= 0;
00275     }
00276     if(s->keyframe){
00277         GET_S(s->version, tmp <= 0U)
00278         s->always_reset= get_rac(&s->c, s->header_state);
00279         s->temporal_decomposition_type= get_symbol(&s->c, s->header_state, 0);
00280         s->temporal_decomposition_count= get_symbol(&s->c, s->header_state, 0);
00281         GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
00282         s->colorspace_type= get_symbol(&s->c, s->header_state, 0);
00283         s->chroma_h_shift= get_symbol(&s->c, s->header_state, 0);
00284         s->chroma_v_shift= get_symbol(&s->c, s->header_state, 0);
00285         s->spatial_scalability= get_rac(&s->c, s->header_state);
00286 //        s->rate_scalability= get_rac(&s->c, s->header_state);
00287         GET_S(s->max_ref_frames, tmp < (unsigned)MAX_REF_FRAMES)
00288         s->max_ref_frames++;
00289 
00290         decode_qlogs(s);
00291     }
00292 
00293     if(!s->keyframe){
00294         if(get_rac(&s->c, s->header_state)){
00295             for(plane_index=0; plane_index<2; plane_index++){
00296                 int htaps, i, sum=0;
00297                 Plane *p= &s->plane[plane_index];
00298                 p->diag_mc= get_rac(&s->c, s->header_state);
00299                 htaps= get_symbol(&s->c, s->header_state, 0)*2 + 2;
00300                 if((unsigned)htaps > HTAPS_MAX || htaps==0)
00301                     return -1;
00302                 p->htaps= htaps;
00303                 for(i= htaps/2; i; i--){
00304                     p->hcoeff[i]= get_symbol(&s->c, s->header_state, 0) * (1-2*(i&1));
00305                     sum += p->hcoeff[i];
00306                 }
00307                 p->hcoeff[0]= 32-sum;
00308             }
00309             s->plane[2].diag_mc= s->plane[1].diag_mc;
00310             s->plane[2].htaps  = s->plane[1].htaps;
00311             memcpy(s->plane[2].hcoeff, s->plane[1].hcoeff, sizeof(s->plane[1].hcoeff));
00312         }
00313         if(get_rac(&s->c, s->header_state)){
00314             GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
00315             decode_qlogs(s);
00316         }
00317     }
00318 
00319     s->spatial_decomposition_type+= get_symbol(&s->c, s->header_state, 1);
00320     if(s->spatial_decomposition_type > 1U){
00321         av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_type %d not supported", s->spatial_decomposition_type);
00322         return -1;
00323     }
00324     if(FFMIN(s->avctx-> width>>s->chroma_h_shift,
00325              s->avctx->height>>s->chroma_v_shift) >> (s->spatial_decomposition_count-1) <= 0){
00326         av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_count %d too large for size", s->spatial_decomposition_count);
00327         return -1;
00328     }
00329 
00330     s->qlog           += get_symbol(&s->c, s->header_state, 1);
00331     s->mv_scale       += get_symbol(&s->c, s->header_state, 1);
00332     s->qbias          += get_symbol(&s->c, s->header_state, 1);
00333     s->block_max_depth+= get_symbol(&s->c, s->header_state, 1);
00334     if(s->block_max_depth > 1 || s->block_max_depth < 0){
00335         av_log(s->avctx, AV_LOG_ERROR, "block_max_depth= %d is too large", s->block_max_depth);
00336         s->block_max_depth= 0;
00337         return -1;
00338     }
00339 
00340     return 0;
00341 }
00342 
00343 static av_cold int decode_init(AVCodecContext *avctx)
00344 {
00345     avctx->pix_fmt= PIX_FMT_YUV420P;
00346 
00347     ff_snow_common_init(avctx);
00348 
00349     return 0;
00350 }
00351 
00352 static void decode_blocks(SnowContext *s){
00353     int x, y;
00354     int w= s->b_width;
00355     int h= s->b_height;
00356 
00357     for(y=0; y<h; y++){
00358         for(x=0; x<w; x++){
00359             decode_q_branch(s, 0, x, y);
00360         }
00361     }
00362 }
00363 
00364 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt){
00365     const uint8_t *buf = avpkt->data;
00366     int buf_size = avpkt->size;
00367     SnowContext *s = avctx->priv_data;
00368     RangeCoder * const c= &s->c;
00369     int bytes_read;
00370     AVFrame *picture = data;
00371     int level, orientation, plane_index;
00372 
00373     ff_init_range_decoder(c, buf, buf_size);
00374     ff_build_rac_states(c, 0.05*(1LL<<32), 256-8);
00375 
00376     s->current_picture.pict_type= AV_PICTURE_TYPE_I; //FIXME I vs. P
00377     if(decode_header(s)<0)
00378         return -1;
00379     ff_snow_common_init_after_header(avctx);
00380 
00381     // realloc slice buffer for the case that spatial_decomposition_count changed
00382     ff_slice_buffer_destroy(&s->sb);
00383     ff_slice_buffer_init(&s->sb, s->plane[0].height, (MB_SIZE >> s->block_max_depth) + s->spatial_decomposition_count * 8 + 1, s->plane[0].width, s->spatial_idwt_buffer);
00384 
00385     for(plane_index=0; plane_index<3; plane_index++){
00386         Plane *p= &s->plane[plane_index];
00387         p->fast_mc= p->diag_mc && p->htaps==6 && p->hcoeff[0]==40
00388                                               && p->hcoeff[1]==-10
00389                                               && p->hcoeff[2]==2;
00390     }
00391 
00392     ff_snow_alloc_blocks(s);
00393 
00394     if(ff_snow_frame_start(s) < 0)
00395         return -1;
00396     //keyframe flag duplication mess FIXME
00397     if(avctx->debug&FF_DEBUG_PICT_INFO)
00398         av_log(avctx, AV_LOG_ERROR, "keyframe:%d qlog:%d\n", s->keyframe, s->qlog);
00399 
00400     decode_blocks(s);
00401 
00402     for(plane_index=0; plane_index<3; plane_index++){
00403         Plane *p= &s->plane[plane_index];
00404         int w= p->width;
00405         int h= p->height;
00406         int x, y;
00407         int decode_state[MAX_DECOMPOSITIONS][4][1]; /* Stored state info for unpack_coeffs. 1 variable per instance. */
00408 
00409         if(s->avctx->debug&2048){
00410             memset(s->spatial_dwt_buffer, 0, sizeof(DWTELEM)*w*h);
00411             predict_plane(s, s->spatial_idwt_buffer, plane_index, 1);
00412 
00413             for(y=0; y<h; y++){
00414                 for(x=0; x<w; x++){
00415                     int v= s->current_picture.data[plane_index][y*s->current_picture.linesize[plane_index] + x];
00416                     s->mconly_picture.data[plane_index][y*s->mconly_picture.linesize[plane_index] + x]= v;
00417                 }
00418             }
00419         }
00420 
00421         {
00422         for(level=0; level<s->spatial_decomposition_count; level++){
00423             for(orientation=level ? 1 : 0; orientation<4; orientation++){
00424                 SubBand *b= &p->band[level][orientation];
00425                 unpack_coeffs(s, b, b->parent, orientation);
00426             }
00427         }
00428         }
00429 
00430         {
00431         const int mb_h= s->b_height << s->block_max_depth;
00432         const int block_size = MB_SIZE >> s->block_max_depth;
00433         const int block_w    = plane_index ? block_size/2 : block_size;
00434         int mb_y;
00435         DWTCompose cs[MAX_DECOMPOSITIONS];
00436         int yd=0, yq=0;
00437         int y;
00438         int end_y;
00439 
00440         ff_spatial_idwt_buffered_init(cs, &s->sb, w, h, 1, s->spatial_decomposition_type, s->spatial_decomposition_count);
00441         for(mb_y=0; mb_y<=mb_h; mb_y++){
00442 
00443             int slice_starty = block_w*mb_y;
00444             int slice_h = block_w*(mb_y+1);
00445             if (!(s->keyframe || s->avctx->debug&512)){
00446                 slice_starty = FFMAX(0, slice_starty - (block_w >> 1));
00447                 slice_h -= (block_w >> 1);
00448             }
00449 
00450             for(level=0; level<s->spatial_decomposition_count; level++){
00451                 for(orientation=level ? 1 : 0; orientation<4; orientation++){
00452                     SubBand *b= &p->band[level][orientation];
00453                     int start_y;
00454                     int end_y;
00455                     int our_mb_start = mb_y;
00456                     int our_mb_end = (mb_y + 1);
00457                     const int extra= 3;
00458                     start_y = (mb_y ? ((block_w * our_mb_start) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra: 0);
00459                     end_y = (((block_w * our_mb_end) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra);
00460                     if (!(s->keyframe || s->avctx->debug&512)){
00461                         start_y = FFMAX(0, start_y - (block_w >> (1+s->spatial_decomposition_count - level)));
00462                         end_y = FFMAX(0, end_y - (block_w >> (1+s->spatial_decomposition_count - level)));
00463                     }
00464                     start_y = FFMIN(b->height, start_y);
00465                     end_y = FFMIN(b->height, end_y);
00466 
00467                     if (start_y != end_y){
00468                         if (orientation == 0){
00469                             SubBand * correlate_band = &p->band[0][0];
00470                             int correlate_end_y = FFMIN(b->height, end_y + 1);
00471                             int correlate_start_y = FFMIN(b->height, (start_y ? start_y + 1 : 0));
00472                             decode_subband_slice_buffered(s, correlate_band, &s->sb, correlate_start_y, correlate_end_y, decode_state[0][0]);
00473                             correlate_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, 1, 0, correlate_start_y, correlate_end_y);
00474                             dequantize_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, start_y, end_y);
00475                         }
00476                         else
00477                             decode_subband_slice_buffered(s, b, &s->sb, start_y, end_y, decode_state[level][orientation]);
00478                     }
00479                 }
00480             }
00481 
00482             for(; yd<slice_h; yd+=4){
00483                 ff_spatial_idwt_buffered_slice(&s->dwt, cs, &s->sb, w, h, 1, s->spatial_decomposition_type, s->spatial_decomposition_count, yd);
00484             }
00485 
00486             if(s->qlog == LOSSLESS_QLOG){
00487                 for(; yq<slice_h && yq<h; yq++){
00488                     IDWTELEM * line = slice_buffer_get_line(&s->sb, yq);
00489                     for(x=0; x<w; x++){
00490                         line[x] <<= FRAC_BITS;
00491                     }
00492                 }
00493             }
00494 
00495             predict_slice_buffered(s, &s->sb, s->spatial_idwt_buffer, plane_index, 1, mb_y);
00496 
00497             y = FFMIN(p->height, slice_starty);
00498             end_y = FFMIN(p->height, slice_h);
00499             while(y < end_y)
00500                 ff_slice_buffer_release(&s->sb, y++);
00501         }
00502 
00503         ff_slice_buffer_flush(&s->sb);
00504         }
00505 
00506     }
00507 
00508     emms_c();
00509 
00510     ff_snow_release_buffer(avctx);
00511 
00512     if(!(s->avctx->debug&2048))
00513         *picture= s->current_picture;
00514     else
00515         *picture= s->mconly_picture;
00516 
00517     *data_size = sizeof(AVFrame);
00518 
00519     bytes_read= c->bytestream - c->bytestream_start;
00520     if(bytes_read ==0) av_log(s->avctx, AV_LOG_ERROR, "error at end of frame\n"); //FIXME
00521 
00522     return bytes_read;
00523 }
00524 
00525 static av_cold int decode_end(AVCodecContext *avctx)
00526 {
00527     SnowContext *s = avctx->priv_data;
00528 
00529     ff_slice_buffer_destroy(&s->sb);
00530 
00531     ff_snow_common_end(s);
00532 
00533     return 0;
00534 }
00535 
00536 AVCodec ff_snow_decoder = {
00537     .name           = "snow",
00538     .type           = AVMEDIA_TYPE_VIDEO,
00539     .id             = CODEC_ID_SNOW,
00540     .priv_data_size = sizeof(SnowContext),
00541     .init           = decode_init,
00542     .close          = decode_end,
00543     .decode         = decode_frame,
00544     .capabilities   = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
00545     .long_name = NULL_IF_CONFIG_SMALL("Snow"),
00546 };
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