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vp9_parser.c
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1 /*
2  * Copyright (C) 2008 Michael Niedermayer
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/intreadwrite.h"
22 #include "parser.h"
23 
24 typedef struct VP9ParseContext {
25  int n_frames; // 1-8
26  int size[8];
28 
29 static void parse_frame(AVCodecParserContext *ctx, const uint8_t *buf, int size)
30 {
31  if (buf[0] & 0x4) {
33  ctx->key_frame = 0;
34  } else {
36  ctx->key_frame = 1;
37  }
38 }
39 
40 static int parse(AVCodecParserContext *ctx,
41  AVCodecContext *avctx,
42  const uint8_t **out_data, int *out_size,
43  const uint8_t *data, int size)
44 {
45  VP9ParseContext *s = ctx->priv_data;
46  int marker;
47 
48  if (size <= 0) {
49  *out_size = 0;
50  *out_data = data;
51 
52  return 0;
53  }
54 
55  if (s->n_frames > 0) {
56  *out_data = data;
57  *out_size = s->size[--s->n_frames];
58  parse_frame(ctx, *out_data, *out_size);
59 
60  return s->n_frames > 0 ? *out_size : size /* i.e. include idx tail */;
61  }
62 
63  marker = data[size - 1];
64  if ((marker & 0xe0) == 0xc0) {
65  int nbytes = 1 + ((marker >> 3) & 0x3);
66  int n_frames = 1 + (marker & 0x7), idx_sz = 2 + n_frames * nbytes;
67 
68  if (size >= idx_sz && data[size - idx_sz] == marker) {
69  const uint8_t *idx = data + size + 1 - idx_sz;
70  int first = 1;
71 
72  switch (nbytes) {
73 #define case_n(a, rd) \
74  case a: \
75  while (n_frames--) { \
76  unsigned sz = rd; \
77  idx += a; \
78  if (sz > size) { \
79  s->n_frames = 0; \
80  av_log(avctx, AV_LOG_ERROR, \
81  "Superframe packet size too big: %u > %d\n", \
82  sz, size); \
83  return size; \
84  } \
85  if (first) { \
86  first = 0; \
87  *out_data = data; \
88  *out_size = sz; \
89  s->n_frames = n_frames; \
90  } else { \
91  s->size[n_frames] = sz; \
92  } \
93  data += sz; \
94  size -= sz; \
95  } \
96  parse_frame(ctx, *out_data, *out_size); \
97  return *out_size
98 
99  case_n(1, *idx);
100  case_n(2, AV_RL16(idx));
101  case_n(3, AV_RL24(idx));
102  case_n(4, AV_RL32(idx));
103  }
104  }
105  }
106 
107  *out_data = data;
108  *out_size = size;
109  parse_frame(ctx, data, size);
110 
111  return size;
112 }
113 
115  .codec_ids = { AV_CODEC_ID_VP9 },
116  .priv_data_size = sizeof(VP9ParseContext),
117  .parser_parse = parse,
118 };