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1 /*
2  * Copyright (c) 2016, Alliance for Open Media. All rights reserved
3  *
4  * This source code is subject to the terms of the BSD 2 Clause License and
5  * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
6  * was not distributed with this source code in the LICENSE file, you can
7  * obtain it at www.aomedia.org/license/software. If the Alliance for Open
8  * Media Patent License 1.0 was not distributed with this source code in the
9  * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
10  */
11 
12 #include <assert.h>
13 #include <limits.h>
14 #include <stdio.h>
15 
16 #include "config/av1_rtcd.h"
17 #include "config/aom_dsp_rtcd.h"
18 #include "config/aom_scale_rtcd.h"
19 
20 #include "aom_dsp/aom_dsp_common.h"
21 #include "aom_mem/aom_mem.h"
22 #include "aom_ports/system_state.h"
23 #include "aom_ports/aom_once.h"
24 #include "aom_ports/aom_timer.h"
25 #include "aom_scale/aom_scale.h"
26 #include "aom_util/aom_thread.h"
27 
28 #include "av1/common/alloccommon.h"
29 #include "av1/common/av1_loopfilter.h"
30 #include "av1/common/onyxc_int.h"
31 #include "av1/common/quant_common.h"
32 #include "av1/common/reconinter.h"
33 #include "av1/common/reconintra.h"
34 
35 #include "av1/decoder/decodeframe.h"
36 #include "av1/decoder/decoder.h"
37 #include "av1/decoder/detokenize.h"
38 #include "av1/decoder/obu.h"
39 
initialize_dec(void)40 static void initialize_dec(void) {
41   av1_rtcd();
42   aom_dsp_rtcd();
43   aom_scale_rtcd();
44   av1_init_intra_predictors();
45   av1_init_wedge_masks();
46 }
47 
dec_setup_mi(AV1_COMMON * cm)48 static void dec_setup_mi(AV1_COMMON *cm) {
49   cm->mi = cm->mip;
50   cm->mi_grid_visible = cm->mi_grid_base;
51   memset(cm->mi_grid_base, 0,
52          cm->mi_stride * cm->mi_rows * sizeof(*cm->mi_grid_base));
53 }
54 
av1_dec_alloc_mi(AV1_COMMON * cm,int mi_size)55 static int av1_dec_alloc_mi(AV1_COMMON *cm, int mi_size) {
56   cm->mip = aom_calloc(mi_size, sizeof(*cm->mip));
57   if (!cm->mip) return 1;
58   cm->mi_alloc_size = mi_size;
59   cm->mi_grid_base =
60       (MB_MODE_INFO **)aom_calloc(mi_size, sizeof(MB_MODE_INFO *));
61   if (!cm->mi_grid_base) return 1;
62   return 0;
63 }
64 
dec_free_mi(AV1_COMMON * cm)65 static void dec_free_mi(AV1_COMMON *cm) {
66   aom_free(cm->mip);
67   cm->mip = NULL;
68   aom_free(cm->mi_grid_base);
69   cm->mi_grid_base = NULL;
70   cm->mi_alloc_size = 0;
71 }
72 
av1_decoder_create(BufferPool * const pool)73 AV1Decoder *av1_decoder_create(BufferPool *const pool) {
74   AV1Decoder *volatile const pbi = aom_memalign(32, sizeof(*pbi));
75   if (!pbi) return NULL;
76   av1_zero(*pbi);
77 
78   AV1_COMMON *volatile const cm = &pbi->common;
79 
80   // The jmp_buf is valid only for the duration of the function that calls
81   // setjmp(). Therefore, this function must reset the 'setjmp' field to 0
82   // before it returns.
83   if (setjmp(cm->error.jmp)) {
84     cm->error.setjmp = 0;
85     av1_decoder_remove(pbi);
86     return NULL;
87   }
88 
89   cm->error.setjmp = 1;
90 
91   CHECK_MEM_ERROR(cm, cm->fc,
92                   (FRAME_CONTEXT *)aom_memalign(32, sizeof(*cm->fc)));
93   CHECK_MEM_ERROR(
94       cm, cm->default_frame_context,
95       (FRAME_CONTEXT *)aom_memalign(32, sizeof(*cm->default_frame_context)));
96   memset(cm->fc, 0, sizeof(*cm->fc));
97   memset(cm->default_frame_context, 0, sizeof(*cm->default_frame_context));
98 
99   pbi->need_resync = 1;
100   aom_once(initialize_dec);
101 
102   // Initialize the references to not point to any frame buffers.
103   for (int i = 0; i < REF_FRAMES; i++) {
104     cm->ref_frame_map[i] = NULL;
105     cm->next_ref_frame_map[i] = NULL;
106   }
107 
108   cm->current_frame.frame_number = 0;
109   pbi->decoding_first_frame = 1;
110   pbi->common.buffer_pool = pool;
111 
112   cm->seq_params.bit_depth = AOM_BITS_8;
113 
114   cm->alloc_mi = av1_dec_alloc_mi;
115   cm->free_mi = dec_free_mi;
116   cm->setup_mi = dec_setup_mi;
117 
118   av1_loop_filter_init(cm);
119 
120   av1_qm_init(cm);
121   av1_loop_restoration_precal();
122 #if CONFIG_ACCOUNTING
123   pbi->acct_enabled = 1;
124   aom_accounting_init(&pbi->accounting);
125 #endif
126 
127   cm->error.setjmp = 0;
128 
129   aom_get_worker_interface()->init(&pbi->lf_worker);
130   pbi->lf_worker.thread_name = "aom lf worker";
131 
132   return pbi;
133 }
134 
av1_dealloc_dec_jobs(struct AV1DecTileMTData * tile_mt_info)135 void av1_dealloc_dec_jobs(struct AV1DecTileMTData *tile_mt_info) {
136   if (tile_mt_info != NULL) {
137 #if CONFIG_MULTITHREAD
138     if (tile_mt_info->job_mutex != NULL) {
139       pthread_mutex_destroy(tile_mt_info->job_mutex);
140       aom_free(tile_mt_info->job_mutex);
141     }
142 #endif
143     aom_free(tile_mt_info->job_queue);
144     // clear the structure as the source of this call may be a resize in which
145     // case this call will be followed by an _alloc() which may fail.
146     av1_zero(*tile_mt_info);
147   }
148 }
149 
av1_dec_free_cb_buf(AV1Decoder * pbi)150 void av1_dec_free_cb_buf(AV1Decoder *pbi) {
151   aom_free(pbi->cb_buffer_base);
152   pbi->cb_buffer_base = NULL;
153   pbi->cb_buffer_alloc_size = 0;
154 }
155 
av1_decoder_remove(AV1Decoder * pbi)156 void av1_decoder_remove(AV1Decoder *pbi) {
157   int i;
158 
159   if (!pbi) return;
160 
161   // Free the tile list output buffer.
162   aom_free_frame_buffer(&pbi->tile_list_outbuf);
163 
164   aom_get_worker_interface()->end(&pbi->lf_worker);
165   aom_free(pbi->lf_worker.data1);
166 
167   if (pbi->thread_data) {
168     for (int worker_idx = 0; worker_idx < pbi->max_threads - 1; worker_idx++) {
169       DecWorkerData *const thread_data = pbi->thread_data + worker_idx;
170       av1_free_mc_tmp_buf(thread_data->td);
171       aom_free(thread_data->td);
172     }
173     aom_free(pbi->thread_data);
174   }
175 
176   for (i = 0; i < pbi->num_workers; ++i) {
177     AVxWorker *const worker = &pbi->tile_workers[i];
178     aom_get_worker_interface()->end(worker);
179   }
180 #if CONFIG_MULTITHREAD
181   if (pbi->row_mt_mutex_ != NULL) {
182     pthread_mutex_destroy(pbi->row_mt_mutex_);
183     aom_free(pbi->row_mt_mutex_);
184   }
185   if (pbi->row_mt_cond_ != NULL) {
186     pthread_cond_destroy(pbi->row_mt_cond_);
187     aom_free(pbi->row_mt_cond_);
188   }
189 #endif
190   for (i = 0; i < pbi->allocated_tiles; i++) {
191     TileDataDec *const tile_data = pbi->tile_data + i;
192     av1_dec_row_mt_dealloc(&tile_data->dec_row_mt_sync);
193   }
194   aom_free(pbi->tile_data);
195   aom_free(pbi->tile_workers);
196 
197   if (pbi->num_workers > 0) {
198     av1_loop_filter_dealloc(&pbi->lf_row_sync);
199     av1_loop_restoration_dealloc(&pbi->lr_row_sync, pbi->num_workers);
200     av1_dealloc_dec_jobs(&pbi->tile_mt_info);
201   }
202 
203   av1_dec_free_cb_buf(pbi);
204 #if CONFIG_ACCOUNTING
205   aom_accounting_clear(&pbi->accounting);
206 #endif
207   av1_free_mc_tmp_buf(&pbi->td);
208 
209   aom_free(pbi);
210 }
211 
av1_visit_palette(AV1Decoder * const pbi,MACROBLOCKD * const xd,int mi_row,int mi_col,aom_reader * r,BLOCK_SIZE bsize,palette_visitor_fn_t visit)212 void av1_visit_palette(AV1Decoder *const pbi, MACROBLOCKD *const xd, int mi_row,
213                        int mi_col, aom_reader *r, BLOCK_SIZE bsize,
214                        palette_visitor_fn_t visit) {
215   if (!is_inter_block(xd->mi[0])) {
216     for (int plane = 0; plane < AOMMIN(2, av1_num_planes(&pbi->common));
217          ++plane) {
218       const struct macroblockd_plane *const pd = &xd->plane[plane];
219       if (is_chroma_reference(mi_row, mi_col, bsize, pd->subsampling_x,
220                               pd->subsampling_y)) {
221         if (xd->mi[0]->palette_mode_info.palette_size[plane])
222           visit(xd, plane, r);
223       } else {
224         assert(xd->mi[0]->palette_mode_info.palette_size[plane] == 0);
225       }
226     }
227   }
228 }
229 
equal_dimensions(const YV12_BUFFER_CONFIG * a,const YV12_BUFFER_CONFIG * b)230 static int equal_dimensions(const YV12_BUFFER_CONFIG *a,
231                             const YV12_BUFFER_CONFIG *b) {
232   return a->y_height == b->y_height && a->y_width == b->y_width &&
233          a->uv_height == b->uv_height && a->uv_width == b->uv_width;
234 }
235 
av1_copy_reference_dec(AV1Decoder * pbi,int idx,YV12_BUFFER_CONFIG * sd)236 aom_codec_err_t av1_copy_reference_dec(AV1Decoder *pbi, int idx,
237                                        YV12_BUFFER_CONFIG *sd) {
238   AV1_COMMON *cm = &pbi->common;
239   const int num_planes = av1_num_planes(cm);
240 
241   const YV12_BUFFER_CONFIG *const cfg = get_ref_frame(cm, idx);
242   if (cfg == NULL) {
243     aom_internal_error(&cm->error, AOM_CODEC_ERROR, "No reference frame");
244     return AOM_CODEC_ERROR;
245   }
246   if (!equal_dimensions(cfg, sd))
247     aom_internal_error(&cm->error, AOM_CODEC_ERROR,
248                        "Incorrect buffer dimensions");
249   else
250     aom_yv12_copy_frame(cfg, sd, num_planes);
251 
252   return cm->error.error_code;
253 }
254 
equal_dimensions_and_border(const YV12_BUFFER_CONFIG * a,const YV12_BUFFER_CONFIG * b)255 static int equal_dimensions_and_border(const YV12_BUFFER_CONFIG *a,
256                                        const YV12_BUFFER_CONFIG *b) {
257   return a->y_height == b->y_height && a->y_width == b->y_width &&
258          a->uv_height == b->uv_height && a->uv_width == b->uv_width &&
259          a->y_stride == b->y_stride && a->uv_stride == b->uv_stride &&
260          a->border == b->border &&
261          (a->flags & YV12_FLAG_HIGHBITDEPTH) ==
262              (b->flags & YV12_FLAG_HIGHBITDEPTH);
263 }
264 
av1_set_reference_dec(AV1_COMMON * cm,int idx,int use_external_ref,YV12_BUFFER_CONFIG * sd)265 aom_codec_err_t av1_set_reference_dec(AV1_COMMON *cm, int idx,
266                                       int use_external_ref,
267                                       YV12_BUFFER_CONFIG *sd) {
268   const int num_planes = av1_num_planes(cm);
269   YV12_BUFFER_CONFIG *ref_buf = NULL;
270 
271   // Get the destination reference buffer.
272   ref_buf = get_ref_frame(cm, idx);
273 
274   if (ref_buf == NULL) {
275     aom_internal_error(&cm->error, AOM_CODEC_ERROR, "No reference frame");
276     return AOM_CODEC_ERROR;
277   }
278 
279   if (!use_external_ref) {
280     if (!equal_dimensions(ref_buf, sd)) {
281       aom_internal_error(&cm->error, AOM_CODEC_ERROR,
282                          "Incorrect buffer dimensions");
283     } else {
284       // Overwrite the reference frame buffer.
285       aom_yv12_copy_frame(sd, ref_buf, num_planes);
286     }
287   } else {
288     if (!equal_dimensions_and_border(ref_buf, sd)) {
289       aom_internal_error(&cm->error, AOM_CODEC_ERROR,
290                          "Incorrect buffer dimensions");
291     } else {
292       // Overwrite the reference frame buffer pointers.
293       // Once we no longer need the external reference buffer, these pointers
294       // are restored.
295       ref_buf->store_buf_adr[0] = ref_buf->y_buffer;
296       ref_buf->store_buf_adr[1] = ref_buf->u_buffer;
297       ref_buf->store_buf_adr[2] = ref_buf->v_buffer;
298       ref_buf->y_buffer = sd->y_buffer;
299       ref_buf->u_buffer = sd->u_buffer;
300       ref_buf->v_buffer = sd->v_buffer;
301       ref_buf->use_external_reference_buffers = 1;
302     }
303   }
304 
305   return cm->error.error_code;
306 }
307 
av1_copy_new_frame_dec(AV1_COMMON * cm,YV12_BUFFER_CONFIG * new_frame,YV12_BUFFER_CONFIG * sd)308 aom_codec_err_t av1_copy_new_frame_dec(AV1_COMMON *cm,
309                                        YV12_BUFFER_CONFIG *new_frame,
310                                        YV12_BUFFER_CONFIG *sd) {
311   const int num_planes = av1_num_planes(cm);
312 
313   if (!equal_dimensions_and_border(new_frame, sd))
314     aom_internal_error(&cm->error, AOM_CODEC_ERROR,
315                        "Incorrect buffer dimensions");
316   else
317     aom_yv12_copy_frame(new_frame, sd, num_planes);
318 
319   return cm->error.error_code;
320 }
321 
release_frame_buffers(AV1Decoder * pbi)322 static void release_frame_buffers(AV1Decoder *pbi) {
323   AV1_COMMON *const cm = &pbi->common;
324   BufferPool *const pool = cm->buffer_pool;
325 
326   cm->cur_frame->buf.corrupted = 1;
327   lock_buffer_pool(pool);
328   // Release all the reference buffers in cm->next_ref_frame_map if the worker
329   // thread is holding them.
330   if (pbi->hold_ref_buf) {
331     for (int ref_index = 0; ref_index < REF_FRAMES; ++ref_index) {
332       decrease_ref_count(cm->next_ref_frame_map[ref_index], pool);
333       cm->next_ref_frame_map[ref_index] = NULL;
334     }
335     pbi->hold_ref_buf = 0;
336   }
337   // Release current frame.
338   decrease_ref_count(cm->cur_frame, pool);
339   unlock_buffer_pool(pool);
340   cm->cur_frame = NULL;
341 }
342 
343 // If any buffer updating is signaled it should be done here.
344 // Consumes a reference to cm->cur_frame.
345 //
346 // This functions returns void. It reports failure by setting
347 // cm->error.error_code.
swap_frame_buffers(AV1Decoder * pbi,int frame_decoded)348 static void swap_frame_buffers(AV1Decoder *pbi, int frame_decoded) {
349   int ref_index = 0, mask;
350   AV1_COMMON *const cm = &pbi->common;
351   BufferPool *const pool = cm->buffer_pool;
352 
353   if (frame_decoded) {
354     lock_buffer_pool(pool);
355 
356     // In ext-tile decoding, the camera frame header is only decoded once. So,
357     // we don't release the references here.
358     if (!pbi->camera_frame_header_ready) {
359       // If we are not holding reference buffers in cm->next_ref_frame_map,
360       // assert that the following two for loops are no-ops.
361       assert(IMPLIES(!pbi->hold_ref_buf,
362                      cm->current_frame.refresh_frame_flags == 0));
363       assert(IMPLIES(!pbi->hold_ref_buf,
364                      cm->show_existing_frame && !pbi->reset_decoder_state));
365 
366       // The following two for loops need to release the reference stored in
367       // cm->ref_frame_map[ref_index] before transferring the reference stored
368       // in cm->next_ref_frame_map[ref_index] to cm->ref_frame_map[ref_index].
369       for (mask = cm->current_frame.refresh_frame_flags; mask; mask >>= 1) {
370         decrease_ref_count(cm->ref_frame_map[ref_index], pool);
371         cm->ref_frame_map[ref_index] = cm->next_ref_frame_map[ref_index];
372         cm->next_ref_frame_map[ref_index] = NULL;
373         ++ref_index;
374       }
375 
376       const int check_on_show_existing_frame =
377           !cm->show_existing_frame || pbi->reset_decoder_state;
378       for (; ref_index < REF_FRAMES && check_on_show_existing_frame;
379            ++ref_index) {
380         decrease_ref_count(cm->ref_frame_map[ref_index], pool);
381         cm->ref_frame_map[ref_index] = cm->next_ref_frame_map[ref_index];
382         cm->next_ref_frame_map[ref_index] = NULL;
383       }
384     }
385 
386     if (cm->show_existing_frame || cm->show_frame) {
387       if (pbi->output_all_layers) {
388         // Append this frame to the output queue
389         if (pbi->num_output_frames >= MAX_NUM_SPATIAL_LAYERS) {
390           // We can't store the new frame anywhere, so drop it and return an
391           // error
392           cm->cur_frame->buf.corrupted = 1;
393           decrease_ref_count(cm->cur_frame, pool);
394           cm->error.error_code = AOM_CODEC_UNSUP_BITSTREAM;
395         } else {
396           pbi->output_frames[pbi->num_output_frames] = cm->cur_frame;
397           pbi->num_output_frames++;
398         }
399       } else {
400         // Replace any existing output frame
401         assert(pbi->num_output_frames == 0 || pbi->num_output_frames == 1);
402         if (pbi->num_output_frames > 0) {
403           decrease_ref_count(pbi->output_frames[0], pool);
404         }
405         pbi->output_frames[0] = cm->cur_frame;
406         pbi->num_output_frames = 1;
407       }
408     } else {
409       decrease_ref_count(cm->cur_frame, pool);
410     }
411 
412     unlock_buffer_pool(pool);
413   } else {
414     // The code here assumes we are not holding reference buffers in
415     // cm->next_ref_frame_map. If this assertion fails, we are leaking the
416     // frame buffer references in cm->next_ref_frame_map.
417     assert(IMPLIES(!pbi->camera_frame_header_ready, !pbi->hold_ref_buf));
418     // Nothing was decoded, so just drop this frame buffer
419     lock_buffer_pool(pool);
420     decrease_ref_count(cm->cur_frame, pool);
421     unlock_buffer_pool(pool);
422   }
423   cm->cur_frame = NULL;
424 
425   if (!pbi->camera_frame_header_ready) {
426     pbi->hold_ref_buf = 0;
427 
428     // Invalidate these references until the next frame starts.
429     for (ref_index = 0; ref_index < INTER_REFS_PER_FRAME; ref_index++) {
430       cm->remapped_ref_idx[ref_index] = INVALID_IDX;
431     }
432   }
433 }
434 
av1_receive_compressed_data(AV1Decoder * pbi,size_t size,const uint8_t ** psource)435 int av1_receive_compressed_data(AV1Decoder *pbi, size_t size,
436                                 const uint8_t **psource) {
437   AV1_COMMON *volatile const cm = &pbi->common;
438   const uint8_t *source = *psource;
439   cm->error.error_code = AOM_CODEC_OK;
440   cm->error.has_detail = 0;
441 
442   if (size == 0) {
443     // This is used to signal that we are missing frames.
444     // We do not know if the missing frame(s) was supposed to update
445     // any of the reference buffers, but we act conservative and
446     // mark only the last buffer as corrupted.
447     //
448     // TODO(jkoleszar): Error concealment is undefined and non-normative
449     // at this point, but if it becomes so, [0] may not always be the correct
450     // thing to do here.
451     RefCntBuffer *ref_buf = get_ref_frame_buf(cm, LAST_FRAME);
452     if (ref_buf != NULL) ref_buf->buf.corrupted = 1;
453   }
454 
455   if (assign_cur_frame_new_fb(cm) == NULL) {
456     cm->error.error_code = AOM_CODEC_MEM_ERROR;
457     return 1;
458   }
459 
460   if (!pbi->camera_frame_header_ready) pbi->hold_ref_buf = 0;
461 
462   // The jmp_buf is valid only for the duration of the function that calls
463   // setjmp(). Therefore, this function must reset the 'setjmp' field to 0
464   // before it returns.
465   if (setjmp(cm->error.jmp)) {
466     const AVxWorkerInterface *const winterface = aom_get_worker_interface();
467     int i;
468 
469     cm->error.setjmp = 0;
470 
471     // Synchronize all threads immediately as a subsequent decode call may
472     // cause a resize invalidating some allocations.
473     winterface->sync(&pbi->lf_worker);
474     for (i = 0; i < pbi->num_workers; ++i) {
475       winterface->sync(&pbi->tile_workers[i]);
476     }
477 
478     release_frame_buffers(pbi);
479     aom_clear_system_state();
480     return -1;
481   }
482 
483   cm->error.setjmp = 1;
484 
485   int frame_decoded =
486       aom_decode_frame_from_obus(pbi, source, source + size, psource);
487 
488   if (frame_decoded < 0) {
489     assert(cm->error.error_code != AOM_CODEC_OK);
490     release_frame_buffers(pbi);
491     cm->error.setjmp = 0;
492     return 1;
493   }
494 
495 #if TXCOEFF_TIMER
496   cm->cum_txcoeff_timer += cm->txcoeff_timer;
497   fprintf(stderr,
498           "txb coeff block number: %d, frame time: %ld, cum time %ld in us\n",
499           cm->txb_count, cm->txcoeff_timer, cm->cum_txcoeff_timer);
500   cm->txcoeff_timer = 0;
501   cm->txb_count = 0;
502 #endif
503 
504   // Note: At this point, this function holds a reference to cm->cur_frame
505   // in the buffer pool. This reference is consumed by swap_frame_buffers().
506   swap_frame_buffers(pbi, frame_decoded);
507 
508   if (frame_decoded) {
509     pbi->decoding_first_frame = 0;
510   }
511 
512   if (cm->error.error_code != AOM_CODEC_OK) {
513     cm->error.setjmp = 0;
514     return 1;
515   }
516 
517   aom_clear_system_state();
518 
519   if (!cm->show_existing_frame) {
520     if (cm->seg.enabled) {
521       if (cm->prev_frame && (cm->mi_rows == cm->prev_frame->mi_rows) &&
522           (cm->mi_cols == cm->prev_frame->mi_cols)) {
523         cm->last_frame_seg_map = cm->prev_frame->seg_map;
524       } else {
525         cm->last_frame_seg_map = NULL;
526       }
527     }
528   }
529 
530   // Update progress in frame parallel decode.
531   cm->error.setjmp = 0;
532 
533   return 0;
534 }
535 
536 // Get the frame at a particular index in the output queue
av1_get_raw_frame(AV1Decoder * pbi,size_t index,YV12_BUFFER_CONFIG ** sd,aom_film_grain_t ** grain_params)537 int av1_get_raw_frame(AV1Decoder *pbi, size_t index, YV12_BUFFER_CONFIG **sd,
538                       aom_film_grain_t **grain_params) {
539   if (index >= pbi->num_output_frames) return -1;
540   *sd = &pbi->output_frames[index]->buf;
541   *grain_params = &pbi->output_frames[index]->film_grain_params;
542   aom_clear_system_state();
543   return 0;
544 }
545 
546 // Get the highest-spatial-layer output
547 // TODO(david.barker): What should this do?
av1_get_frame_to_show(AV1Decoder * pbi,YV12_BUFFER_CONFIG * frame)548 int av1_get_frame_to_show(AV1Decoder *pbi, YV12_BUFFER_CONFIG *frame) {
549   if (pbi->num_output_frames == 0) return -1;
550 
551   *frame = pbi->output_frames[pbi->num_output_frames - 1]->buf;
552   return 0;
553 }
554