lavc: fix support of unofficial pix_fmt extensions of jpeg
[ffmpeg.git] / libavcodec / snowdec.c
1 /*
2  * Copyright (C) 2004 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20
21 #include "libavutil/intmath.h"
22 #include "libavutil/log.h"
23 #include "libavutil/opt.h"
24 #include "avcodec.h"
25 #include "dsputil.h"
26 #include "dwt.h"
27 #include "snow.h"
28
29 #include "rangecoder.h"
30 #include "mathops.h"
31
32 #include "mpegvideo.h"
33 #include "h263.h"
34
35 #undef NDEBUG
36 #include <assert.h>
37
38 static av_always_inline void predict_slice_buffered(SnowContext *s, slice_buffer * sb, IDWTELEM * old_buffer, int plane_index, int add, int mb_y){
39     Plane *p= &s->plane[plane_index];
40     const int mb_w= s->b_width  << s->block_max_depth;
41     const int mb_h= s->b_height << s->block_max_depth;
42     int x, y, mb_x;
43     int block_size = MB_SIZE >> s->block_max_depth;
44     int block_w    = plane_index ? block_size/2 : block_size;
45     const uint8_t *obmc  = plane_index ? ff_obmc_tab[s->block_max_depth+1] : ff_obmc_tab[s->block_max_depth];
46     int obmc_stride= plane_index ? block_size : 2*block_size;
47     int ref_stride= s->current_picture.linesize[plane_index];
48     uint8_t *dst8= s->current_picture.data[plane_index];
49     int w= p->width;
50     int h= p->height;
51
52     if(s->keyframe || (s->avctx->debug&512)){
53         if(mb_y==mb_h)
54             return;
55
56         if(add){
57             for(y=block_w*mb_y; y<FFMIN(h,block_w*(mb_y+1)); y++){
58 //                DWTELEM * line = slice_buffer_get_line(sb, y);
59                 IDWTELEM * line = sb->line[y];
60                 for(x=0; x<w; x++){
61 //                    int v= buf[x + y*w] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
62                     int v= line[x] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
63                     v >>= FRAC_BITS;
64                     if(v&(~255)) v= ~(v>>31);
65                     dst8[x + y*ref_stride]= v;
66                 }
67             }
68         }else{
69             for(y=block_w*mb_y; y<FFMIN(h,block_w*(mb_y+1)); y++){
70 //                DWTELEM * line = slice_buffer_get_line(sb, y);
71                 IDWTELEM * line = sb->line[y];
72                 for(x=0; x<w; x++){
73                     line[x] -= 128 << FRAC_BITS;
74 //                    buf[x + y*w]-= 128<<FRAC_BITS;
75                 }
76             }
77         }
78
79         return;
80     }
81
82     for(mb_x=0; mb_x<=mb_w; mb_x++){
83         add_yblock(s, 1, sb, old_buffer, dst8, obmc,
84                    block_w*mb_x - block_w/2,
85                    block_w*mb_y - block_w/2,
86                    block_w, block_w,
87                    w, h,
88                    w, ref_stride, obmc_stride,
89                    mb_x - 1, mb_y - 1,
90                    add, 0, plane_index);
91     }
92 }
93
94 static inline void decode_subband_slice_buffered(SnowContext *s, SubBand *b, slice_buffer * sb, int start_y, int h, int save_state[1]){
95     const int w= b->width;
96     int y;
97     const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
98     int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
99     int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
100     int new_index = 0;
101
102     if(b->ibuf == s->spatial_idwt_buffer || s->qlog == LOSSLESS_QLOG){
103         qadd= 0;
104         qmul= 1<<QEXPSHIFT;
105     }
106
107     /* If we are on the second or later slice, restore our index. */
108     if (start_y != 0)
109         new_index = save_state[0];
110
111
112     for(y=start_y; y<h; y++){
113         int x = 0;
114         int v;
115         IDWTELEM * line = slice_buffer_get_line(sb, y * b->stride_line + b->buf_y_offset) + b->buf_x_offset;
116         memset(line, 0, b->width*sizeof(IDWTELEM));
117         v = b->x_coeff[new_index].coeff;
118         x = b->x_coeff[new_index++].x;
119         while(x < w){
120             register int t= ( (v>>1)*qmul + qadd)>>QEXPSHIFT;
121             register int u= -(v&1);
122             line[x] = (t^u) - u;
123
124             v = b->x_coeff[new_index].coeff;
125             x = b->x_coeff[new_index++].x;
126         }
127     }
128
129     /* Save our variables for the next slice. */
130     save_state[0] = new_index;
131
132     return;
133 }
134
135 static int decode_q_branch(SnowContext *s, int level, int x, int y){
136     const int w= s->b_width << s->block_max_depth;
137     const int rem_depth= s->block_max_depth - level;
138     const int index= (x + y*w) << rem_depth;
139     int trx= (x+1)<<rem_depth;
140     const BlockNode *left  = x ? &s->block[index-1] : &null_block;
141     const BlockNode *top   = y ? &s->block[index-w] : &null_block;
142     const BlockNode *tl    = y && x ? &s->block[index-w-1] : left;
143     const BlockNode *tr    = y && trx<w && ((x&1)==0 || level==0) ? &s->block[index-w+(1<<rem_depth)] : tl; //FIXME use lt
144     int s_context= 2*left->level + 2*top->level + tl->level + tr->level;
145     int res;
146
147     if(s->keyframe){
148         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);
149         return 0;
150     }
151
152     if(level==s->block_max_depth || get_rac(&s->c, &s->block_state[4 + s_context])){
153         int type, mx, my;
154         int l = left->color[0];
155         int cb= left->color[1];
156         int cr= left->color[2];
157         int ref = 0;
158         int ref_context= av_log2(2*left->ref) + av_log2(2*top->ref);
159         int mx_context= av_log2(2*FFABS(left->mx - top->mx)) + 0*av_log2(2*FFABS(tr->mx - top->mx));
160         int my_context= av_log2(2*FFABS(left->my - top->my)) + 0*av_log2(2*FFABS(tr->my - top->my));
161
162         type= get_rac(&s->c, &s->block_state[1 + left->type + top->type]) ? BLOCK_INTRA : 0;
163
164         if(type){
165             pred_mv(s, &mx, &my, 0, left, top, tr);
166             l += get_symbol(&s->c, &s->block_state[32], 1);
167             cb+= get_symbol(&s->c, &s->block_state[64], 1);
168             cr+= get_symbol(&s->c, &s->block_state[96], 1);
169         }else{
170             if(s->ref_frames > 1)
171                 ref= get_symbol(&s->c, &s->block_state[128 + 1024 + 32*ref_context], 0);
172             if (ref >= s->ref_frames) {
173                 av_log(s->avctx, AV_LOG_ERROR, "Invalid ref\n");
174                 return AVERROR_INVALIDDATA;
175             }
176             pred_mv(s, &mx, &my, ref, left, top, tr);
177             mx+= get_symbol(&s->c, &s->block_state[128 + 32*(mx_context + 16*!!ref)], 1);
178             my+= get_symbol(&s->c, &s->block_state[128 + 32*(my_context + 16*!!ref)], 1);
179         }
180         set_blocks(s, level, x, y, l, cb, cr, mx, my, ref, type);
181     }else{
182         if ((res = decode_q_branch(s, level+1, 2*x+0, 2*y+0)) < 0 ||
183             (res = decode_q_branch(s, level+1, 2*x+1, 2*y+0)) < 0 ||
184             (res = decode_q_branch(s, level+1, 2*x+0, 2*y+1)) < 0 ||
185             (res = decode_q_branch(s, level+1, 2*x+1, 2*y+1)) < 0)
186             return res;
187     }
188     return 0;
189 }
190
191 static void dequantize_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int start_y, int end_y){
192     const int w= b->width;
193     const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
194     const int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
195     const int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
196     int x,y;
197
198     if(s->qlog == LOSSLESS_QLOG) return;
199
200     for(y=start_y; y<end_y; y++){
201 //        DWTELEM * line = slice_buffer_get_line_from_address(sb, src + (y * stride));
202         IDWTELEM * line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
203         for(x=0; x<w; x++){
204             int i= line[x];
205             if(i<0){
206                 line[x]= -((-i*qmul + qadd)>>(QEXPSHIFT)); //FIXME try different bias
207             }else if(i>0){
208                 line[x]=  (( i*qmul + qadd)>>(QEXPSHIFT));
209             }
210         }
211     }
212 }
213
214 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){
215     const int w= b->width;
216     int x,y;
217
218     IDWTELEM * line=0; // silence silly "could be used without having been initialized" warning
219     IDWTELEM * prev;
220
221     if (start_y != 0)
222         line = slice_buffer_get_line(sb, ((start_y - 1) * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
223
224     for(y=start_y; y<end_y; y++){
225         prev = line;
226 //        line = slice_buffer_get_line_from_address(sb, src + (y * stride));
227         line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
228         for(x=0; x<w; x++){
229             if(x){
230                 if(use_median){
231                     if(y && x+1<w) line[x] += mid_pred(line[x - 1], prev[x], prev[x + 1]);
232                     else  line[x] += line[x - 1];
233                 }else{
234                     if(y) line[x] += mid_pred(line[x - 1], prev[x], line[x - 1] + prev[x] - prev[x - 1]);
235                     else  line[x] += line[x - 1];
236                 }
237             }else{
238                 if(y) line[x] += prev[x];
239             }
240         }
241     }
242 }
243
244 static void decode_qlogs(SnowContext *s){
245     int plane_index, level, orientation;
246
247     for(plane_index=0; plane_index<3; plane_index++){
248         for(level=0; level<s->spatial_decomposition_count; level++){
249             for(orientation=level ? 1:0; orientation<4; orientation++){
250                 int q;
251                 if     (plane_index==2) q= s->plane[1].band[level][orientation].qlog;
252                 else if(orientation==2) q= s->plane[plane_index].band[level][1].qlog;
253                 else                    q= get_symbol(&s->c, s->header_state, 1);
254                 s->plane[plane_index].band[level][orientation].qlog= q;
255             }
256         }
257     }
258 }
259
260 #define GET_S(dst, check) \
261     tmp= get_symbol(&s->c, s->header_state, 0);\
262     if(!(check)){\
263         av_log(s->avctx, AV_LOG_ERROR, "Error " #dst " is %d\n", tmp);\
264         return -1;\
265     }\
266     dst= tmp;
267
268 static int decode_header(SnowContext *s){
269     int plane_index, tmp;
270     uint8_t kstate[32];
271
272     memset(kstate, MID_STATE, sizeof(kstate));
273
274     s->keyframe= get_rac(&s->c, kstate);
275     if(s->keyframe || s->always_reset){
276         ff_snow_reset_contexts(s);
277         s->spatial_decomposition_type=
278         s->qlog=
279         s->qbias=
280         s->mv_scale=
281         s->block_max_depth= 0;
282     }
283     if(s->keyframe){
284         GET_S(s->version, tmp <= 0U)
285         s->always_reset= get_rac(&s->c, s->header_state);
286         s->temporal_decomposition_type= get_symbol(&s->c, s->header_state, 0);
287         s->temporal_decomposition_count= get_symbol(&s->c, s->header_state, 0);
288         GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
289         s->colorspace_type= get_symbol(&s->c, s->header_state, 0);
290         s->chroma_h_shift= get_symbol(&s->c, s->header_state, 0);
291         s->chroma_v_shift= get_symbol(&s->c, s->header_state, 0);
292         s->spatial_scalability= get_rac(&s->c, s->header_state);
293 //        s->rate_scalability= get_rac(&s->c, s->header_state);
294         GET_S(s->max_ref_frames, tmp < (unsigned)MAX_REF_FRAMES)
295         s->max_ref_frames++;
296
297         decode_qlogs(s);
298     }
299
300     if(!s->keyframe){
301         if(get_rac(&s->c, s->header_state)){
302             for(plane_index=0; plane_index<2; plane_index++){
303                 int htaps, i, sum=0;
304                 Plane *p= &s->plane[plane_index];
305                 p->diag_mc= get_rac(&s->c, s->header_state);
306                 htaps= get_symbol(&s->c, s->header_state, 0)*2 + 2;
307                 if((unsigned)htaps > HTAPS_MAX || htaps==0)
308                     return -1;
309                 p->htaps= htaps;
310                 for(i= htaps/2; i; i--){
311                     p->hcoeff[i]= get_symbol(&s->c, s->header_state, 0) * (1-2*(i&1));
312                     sum += p->hcoeff[i];
313                 }
314                 p->hcoeff[0]= 32-sum;
315             }
316             s->plane[2].diag_mc= s->plane[1].diag_mc;
317             s->plane[2].htaps  = s->plane[1].htaps;
318             memcpy(s->plane[2].hcoeff, s->plane[1].hcoeff, sizeof(s->plane[1].hcoeff));
319         }
320         if(get_rac(&s->c, s->header_state)){
321             GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
322             decode_qlogs(s);
323         }
324     }
325
326     s->spatial_decomposition_type+= get_symbol(&s->c, s->header_state, 1);
327     if(s->spatial_decomposition_type > 1U){
328         av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_type %d not supported\n", s->spatial_decomposition_type);
329         return -1;
330     }
331     if(FFMIN(s->avctx-> width>>s->chroma_h_shift,
332              s->avctx->height>>s->chroma_v_shift) >> (s->spatial_decomposition_count-1) <= 0){
333         av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_count %d too large for size\n", s->spatial_decomposition_count);
334         return -1;
335     }
336
337     if (s->chroma_h_shift != 1 || s->chroma_v_shift != 1) {
338         av_log(s->avctx, AV_LOG_ERROR, "Invalid chroma shift\n");
339         return AVERROR_PATCHWELCOME;
340     }
341
342     s->qlog           += get_symbol(&s->c, s->header_state, 1);
343     s->mv_scale       += get_symbol(&s->c, s->header_state, 1);
344     s->qbias          += get_symbol(&s->c, s->header_state, 1);
345     s->block_max_depth+= get_symbol(&s->c, s->header_state, 1);
346     if(s->block_max_depth > 1 || s->block_max_depth < 0){
347         av_log(s->avctx, AV_LOG_ERROR, "block_max_depth= %d is too large\n", s->block_max_depth);
348         s->block_max_depth= 0;
349         return -1;
350     }
351
352     return 0;
353 }
354
355 static av_cold int decode_init(AVCodecContext *avctx)
356 {
357     avctx->pix_fmt= PIX_FMT_YUV420P;
358
359     ff_snow_common_init(avctx);
360
361     return 0;
362 }
363
364 static int decode_blocks(SnowContext *s){
365     int x, y;
366     int w= s->b_width;
367     int h= s->b_height;
368     int res;
369
370     for(y=0; y<h; y++){
371         for(x=0; x<w; x++){
372             if ((res = decode_q_branch(s, 0, x, y)) < 0)
373                 return res;
374         }
375     }
376     return 0;
377 }
378
379 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt){
380     const uint8_t *buf = avpkt->data;
381     int buf_size = avpkt->size;
382     SnowContext *s = avctx->priv_data;
383     RangeCoder * const c= &s->c;
384     int bytes_read;
385     AVFrame *picture = data;
386     int level, orientation, plane_index;
387     int res;
388
389     ff_init_range_decoder(c, buf, buf_size);
390     ff_build_rac_states(c, 0.05*(1LL<<32), 256-8);
391
392     s->current_picture.pict_type= AV_PICTURE_TYPE_I; //FIXME I vs. P
393     if(decode_header(s)<0)
394         return -1;
395     ff_snow_common_init_after_header(avctx);
396
397     // realloc slice buffer for the case that spatial_decomposition_count changed
398     ff_slice_buffer_destroy(&s->sb);
399     if ((res = ff_slice_buffer_init(&s->sb, s->plane[0].height,
400                                     (MB_SIZE >> s->block_max_depth) +
401                                     s->spatial_decomposition_count * 8 + 1,
402                                     s->plane[0].width,
403                                     s->spatial_idwt_buffer)) < 0)
404         return res;
405
406     for(plane_index=0; plane_index<3; plane_index++){
407         Plane *p= &s->plane[plane_index];
408         p->fast_mc= p->diag_mc && p->htaps==6 && p->hcoeff[0]==40
409                                               && p->hcoeff[1]==-10
410                                               && p->hcoeff[2]==2;
411     }
412
413     ff_snow_alloc_blocks(s);
414
415     if(ff_snow_frame_start(s) < 0)
416         return -1;
417     //keyframe flag duplication mess FIXME
418     if(avctx->debug&FF_DEBUG_PICT_INFO)
419         av_log(avctx, AV_LOG_ERROR, "keyframe:%d qlog:%d\n", s->keyframe, s->qlog);
420
421     if ((res = decode_blocks(s)) < 0)
422         return res;
423
424     for(plane_index=0; plane_index<3; plane_index++){
425         Plane *p= &s->plane[plane_index];
426         int w= p->width;
427         int h= p->height;
428         int x, y;
429         int decode_state[MAX_DECOMPOSITIONS][4][1]; /* Stored state info for unpack_coeffs. 1 variable per instance. */
430
431         if(s->avctx->debug&2048){
432             memset(s->spatial_dwt_buffer, 0, sizeof(DWTELEM)*w*h);
433             predict_plane(s, s->spatial_idwt_buffer, plane_index, 1);
434
435             for(y=0; y<h; y++){
436                 for(x=0; x<w; x++){
437                     int v= s->current_picture.data[plane_index][y*s->current_picture.linesize[plane_index] + x];
438                     s->mconly_picture.data[plane_index][y*s->mconly_picture.linesize[plane_index] + x]= v;
439                 }
440             }
441         }
442
443         {
444         for(level=0; level<s->spatial_decomposition_count; level++){
445             for(orientation=level ? 1 : 0; orientation<4; orientation++){
446                 SubBand *b= &p->band[level][orientation];
447                 unpack_coeffs(s, b, b->parent, orientation);
448             }
449         }
450         }
451
452         {
453         const int mb_h= s->b_height << s->block_max_depth;
454         const int block_size = MB_SIZE >> s->block_max_depth;
455         const int block_w    = plane_index ? block_size/2 : block_size;
456         int mb_y;
457         DWTCompose cs[MAX_DECOMPOSITIONS];
458         int yd=0, yq=0;
459         int y;
460         int end_y;
461
462         ff_spatial_idwt_buffered_init(cs, &s->sb, w, h, 1, s->spatial_decomposition_type, s->spatial_decomposition_count);
463         for(mb_y=0; mb_y<=mb_h; mb_y++){
464
465             int slice_starty = block_w*mb_y;
466             int slice_h = block_w*(mb_y+1);
467             if (!(s->keyframe || s->avctx->debug&512)){
468                 slice_starty = FFMAX(0, slice_starty - (block_w >> 1));
469                 slice_h -= (block_w >> 1);
470             }
471
472             for(level=0; level<s->spatial_decomposition_count; level++){
473                 for(orientation=level ? 1 : 0; orientation<4; orientation++){
474                     SubBand *b= &p->band[level][orientation];
475                     int start_y;
476                     int end_y;
477                     int our_mb_start = mb_y;
478                     int our_mb_end = (mb_y + 1);
479                     const int extra= 3;
480                     start_y = (mb_y ? ((block_w * our_mb_start) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra: 0);
481                     end_y = (((block_w * our_mb_end) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra);
482                     if (!(s->keyframe || s->avctx->debug&512)){
483                         start_y = FFMAX(0, start_y - (block_w >> (1+s->spatial_decomposition_count - level)));
484                         end_y = FFMAX(0, end_y - (block_w >> (1+s->spatial_decomposition_count - level)));
485                     }
486                     start_y = FFMIN(b->height, start_y);
487                     end_y = FFMIN(b->height, end_y);
488
489                     if (start_y != end_y){
490                         if (orientation == 0){
491                             SubBand * correlate_band = &p->band[0][0];
492                             int correlate_end_y = FFMIN(b->height, end_y + 1);
493                             int correlate_start_y = FFMIN(b->height, (start_y ? start_y + 1 : 0));
494                             decode_subband_slice_buffered(s, correlate_band, &s->sb, correlate_start_y, correlate_end_y, decode_state[0][0]);
495                             correlate_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, 1, 0, correlate_start_y, correlate_end_y);
496                             dequantize_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, start_y, end_y);
497                         }
498                         else
499                             decode_subband_slice_buffered(s, b, &s->sb, start_y, end_y, decode_state[level][orientation]);
500                     }
501                 }
502             }
503
504             for(; yd<slice_h; yd+=4){
505                 ff_spatial_idwt_buffered_slice(&s->dwt, cs, &s->sb, w, h, 1, s->spatial_decomposition_type, s->spatial_decomposition_count, yd);
506             }
507
508             if(s->qlog == LOSSLESS_QLOG){
509                 for(; yq<slice_h && yq<h; yq++){
510                     IDWTELEM * line = slice_buffer_get_line(&s->sb, yq);
511                     for(x=0; x<w; x++){
512                         line[x] <<= FRAC_BITS;
513                     }
514                 }
515             }
516
517             predict_slice_buffered(s, &s->sb, s->spatial_idwt_buffer, plane_index, 1, mb_y);
518
519             y = FFMIN(p->height, slice_starty);
520             end_y = FFMIN(p->height, slice_h);
521             while(y < end_y)
522                 ff_slice_buffer_release(&s->sb, y++);
523         }
524
525         ff_slice_buffer_flush(&s->sb);
526         }
527
528     }
529
530     emms_c();
531
532     ff_snow_release_buffer(avctx);
533
534     if(!(s->avctx->debug&2048))
535         *picture= s->current_picture;
536     else
537         *picture= s->mconly_picture;
538
539     *data_size = sizeof(AVFrame);
540
541     bytes_read= c->bytestream - c->bytestream_start;
542     if(bytes_read ==0) av_log(s->avctx, AV_LOG_ERROR, "error at end of frame\n"); //FIXME
543
544     return bytes_read;
545 }
546
547 static av_cold int decode_end(AVCodecContext *avctx)
548 {
549     SnowContext *s = avctx->priv_data;
550
551     ff_slice_buffer_destroy(&s->sb);
552
553     ff_snow_common_end(s);
554
555     return 0;
556 }
557
558 AVCodec ff_snow_decoder = {
559     .name           = "snow",
560     .type           = AVMEDIA_TYPE_VIDEO,
561     .id             = CODEC_ID_SNOW,
562     .priv_data_size = sizeof(SnowContext),
563     .init           = decode_init,
564     .close          = decode_end,
565     .decode         = decode_frame,
566     .capabilities   = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
567     .long_name      = NULL_IF_CONFIG_SMALL("Snow"),
568 };