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h264_mp4toannexb_bsf.c
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1 /*
2  * H.264 MP4 to Annex B byte stream format filter
3  * Copyright (c) 2007 Benoit Fouet <benoit.fouet@free.fr>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include <string.h>
23 
24 #include "libavutil/intreadwrite.h"
25 #include "libavutil/mem.h"
26 #include "avcodec.h"
27 
28 typedef struct H264BSFContext {
29  uint8_t length_size;
30  uint8_t first_idr;
31  int extradata_parsed;
32 } H264BSFContext;
33 
34 static int alloc_and_copy(uint8_t **poutbuf, int *poutbuf_size,
35  const uint8_t *sps_pps, uint32_t sps_pps_size,
36  const uint8_t *in, uint32_t in_size) {
37  uint32_t offset = *poutbuf_size;
38  uint8_t nal_header_size = offset ? 3 : 4;
39  void *tmp;
40 
41  *poutbuf_size += sps_pps_size+in_size+nal_header_size;
42  tmp = av_realloc(*poutbuf, *poutbuf_size);
43  if (!tmp)
44  return AVERROR(ENOMEM);
45  *poutbuf = tmp;
46  if (sps_pps)
47  memcpy(*poutbuf+offset, sps_pps, sps_pps_size);
48  memcpy(*poutbuf+sps_pps_size+nal_header_size+offset, in, in_size);
49  if (!offset) {
50  AV_WB32(*poutbuf+sps_pps_size, 1);
51  } else {
52  (*poutbuf+offset+sps_pps_size)[0] = (*poutbuf+offset+sps_pps_size)[1] = 0;
53  (*poutbuf+offset+sps_pps_size)[2] = 1;
54  }
55 
56  return 0;
57 }
58 
59 static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
60  AVCodecContext *avctx, const char *args,
61  uint8_t **poutbuf, int *poutbuf_size,
62  const uint8_t *buf, int buf_size,
63  int keyframe) {
64  H264BSFContext *ctx = bsfc->priv_data;
65  int i;
66  uint8_t unit_type;
67  int32_t nal_size;
68  uint32_t cumul_size = 0;
69  const uint8_t *buf_end = buf + buf_size;
70  int ret = AVERROR(EINVAL);
71 
72  /* nothing to filter */
73  if (!avctx->extradata || avctx->extradata_size < 6) {
74  *poutbuf = (uint8_t*) buf;
75  *poutbuf_size = buf_size;
76  return 0;
77  }
78 
79  /* retrieve sps and pps NAL units from extradata */
80  if (!ctx->extradata_parsed) {
81  uint16_t unit_size;
82  uint64_t total_size = 0;
83  uint8_t *out = NULL, unit_nb, sps_done = 0, sps_seen = 0, pps_seen = 0;
84  const uint8_t *extradata = avctx->extradata+4;
85  static const uint8_t nalu_header[4] = {0, 0, 0, 1};
86 
87  /* retrieve length coded size */
88  ctx->length_size = (*extradata++ & 0x3) + 1;
89 
90  /* retrieve sps and pps unit(s) */
91  unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
92  if (!unit_nb) {
93  goto pps;
94  } else {
95  sps_seen = 1;
96  }
97 
98  while (unit_nb--) {
99  void *tmp;
100 
101  unit_size = AV_RB16(extradata);
102  total_size += unit_size+4;
103  if (total_size > INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE ||
104  extradata+2+unit_size > avctx->extradata+avctx->extradata_size) {
105  av_free(out);
106  return AVERROR(EINVAL);
107  }
108  tmp = av_realloc(out, total_size + FF_INPUT_BUFFER_PADDING_SIZE);
109  if (!tmp) {
110  av_free(out);
111  return AVERROR(ENOMEM);
112  }
113  out = tmp;
114  memcpy(out+total_size-unit_size-4, nalu_header, 4);
115  memcpy(out+total_size-unit_size, extradata+2, unit_size);
116  extradata += 2+unit_size;
117 pps:
118  if (!unit_nb && !sps_done++) {
119  unit_nb = *extradata++; /* number of pps unit(s) */
120  if (unit_nb)
121  pps_seen = 1;
122  }
123  }
124 
125  if(out)
126  memset(out + total_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
127 
128  if (!sps_seen)
129  av_log(avctx, AV_LOG_WARNING, "Warning: SPS NALU missing or invalid. The resulting stream may not play.\n");
130  if (!pps_seen)
131  av_log(avctx, AV_LOG_WARNING, "Warning: PPS NALU missing or invalid. The resulting stream may not play.\n");
132 
133  av_free(avctx->extradata);
134  avctx->extradata = out;
135  avctx->extradata_size = total_size;
136  ctx->first_idr = 1;
137  ctx->extradata_parsed = 1;
138  }
139 
140  *poutbuf_size = 0;
141  *poutbuf = NULL;
142  do {
143  ret= AVERROR(EINVAL);
144  if (buf + ctx->length_size > buf_end)
145  goto fail;
146 
147  for (nal_size = 0, i = 0; i<ctx->length_size; i++)
148  nal_size = (nal_size << 8) | buf[i];
149 
150  buf += ctx->length_size;
151  unit_type = *buf & 0x1f;
152 
153  if (buf + nal_size > buf_end || nal_size < 0)
154  goto fail;
155 
156  /* prepend only to the first type 5 NAL unit of an IDR picture */
157  if (ctx->first_idr && unit_type == 5) {
158  if ((ret=alloc_and_copy(poutbuf, poutbuf_size,
159  avctx->extradata, avctx->extradata_size,
160  buf, nal_size)) < 0)
161  goto fail;
162  ctx->first_idr = 0;
163  } else {
164  if ((ret=alloc_and_copy(poutbuf, poutbuf_size,
165  NULL, 0,
166  buf, nal_size)) < 0)
167  goto fail;
168  if (!ctx->first_idr && unit_type == 1)
169  ctx->first_idr = 1;
170  }
171 
172  buf += nal_size;
173  cumul_size += nal_size + ctx->length_size;
174  } while (cumul_size < buf_size);
175 
176  return 1;
177 
178 fail:
179  av_freep(poutbuf);
180  *poutbuf_size = 0;
181  return ret;
182 }
183 
184 AVBitStreamFilter ff_h264_mp4toannexb_bsf = {
185  "h264_mp4toannexb",
186  sizeof(H264BSFContext),
187  h264_mp4toannexb_filter,
188 };
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