FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
h264_mp4toannexb_bsf.c
Go to the documentation of this file.
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  int32_t sps_offset;
30  int32_t pps_offset;
31  uint8_t length_size;
32  uint8_t new_idr;
33  uint8_t idr_sps_seen;
34  uint8_t idr_pps_seen;
35  int extradata_parsed;
36 } H264BSFContext;
37 
38 static int alloc_and_copy(uint8_t **poutbuf, int *poutbuf_size,
39  const uint8_t *sps_pps, uint32_t sps_pps_size,
40  const uint8_t *in, uint32_t in_size)
41 {
42  uint32_t offset = *poutbuf_size;
43  uint8_t nal_header_size = offset ? 3 : 4;
44  int err;
45 
46  *poutbuf_size += sps_pps_size + in_size + nal_header_size;
47  if ((err = av_reallocp(poutbuf,
48  *poutbuf_size + FF_INPUT_BUFFER_PADDING_SIZE)) < 0) {
49  *poutbuf_size = 0;
50  return err;
51  }
52  if (sps_pps)
53  memcpy(*poutbuf + offset, sps_pps, sps_pps_size);
54  memcpy(*poutbuf + sps_pps_size + nal_header_size + offset, in, in_size);
55  if (!offset) {
56  AV_WB32(*poutbuf + sps_pps_size, 1);
57  } else {
58  (*poutbuf + offset + sps_pps_size)[0] =
59  (*poutbuf + offset + sps_pps_size)[1] = 0;
60  (*poutbuf + offset + sps_pps_size)[2] = 1;
61  }
62 
63  return 0;
64 }
65 
66 static int h264_extradata_to_annexb(H264BSFContext *ctx, AVCodecContext *avctx, const int padding)
67 {
68  uint16_t unit_size;
69  uint64_t total_size = 0;
70  uint8_t *out = NULL, unit_nb, sps_done = 0,
71  sps_seen = 0, pps_seen = 0;
72  const uint8_t *extradata = avctx->extradata + 4;
73  static const uint8_t nalu_header[4] = { 0, 0, 0, 1 };
74  int length_size = (*extradata++ & 0x3) + 1; // retrieve length coded size
75 
76  ctx->sps_offset = ctx->pps_offset = -1;
77 
78  /* retrieve sps and pps unit(s) */
79  unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
80  if (!unit_nb) {
81  goto pps;
82  } else {
83  ctx->sps_offset = 0;
84  sps_seen = 1;
85  }
86 
87  while (unit_nb--) {
88  int err;
89 
90  unit_size = AV_RB16(extradata);
91  total_size += unit_size + 4;
92  if (total_size > INT_MAX - padding) {
93  av_log(avctx, AV_LOG_ERROR,
94  "Too big extradata size, corrupted stream or invalid MP4/AVCC bitstream\n");
95  av_free(out);
96  return AVERROR(EINVAL);
97  }
98  if (extradata + 2 + unit_size > avctx->extradata + avctx->extradata_size) {
99  av_log(avctx, AV_LOG_ERROR, "Packet header is not contained in global extradata, "
100  "corrupted stream or invalid MP4/AVCC bitstream\n");
101  av_free(out);
102  return AVERROR(EINVAL);
103  }
104  if ((err = av_reallocp(&out, total_size + padding)) < 0)
105  return err;
106  memcpy(out + total_size - unit_size - 4, nalu_header, 4);
107  memcpy(out + total_size - unit_size, extradata + 2, unit_size);
108  extradata += 2 + unit_size;
109 pps:
110  if (!unit_nb && !sps_done++) {
111  unit_nb = *extradata++; /* number of pps unit(s) */
112  if (unit_nb) {
113  ctx->pps_offset = (extradata - 1) - (avctx->extradata + 4);
114  pps_seen = 1;
115  }
116  }
117  }
118 
119  if (out)
120  memset(out + total_size, 0, padding);
121 
122  if (!sps_seen)
123  av_log(avctx, AV_LOG_WARNING,
124  "Warning: SPS NALU missing or invalid. "
125  "The resulting stream may not play.\n");
126 
127  if (!pps_seen)
128  av_log(avctx, AV_LOG_WARNING,
129  "Warning: PPS NALU missing or invalid. "
130  "The resulting stream may not play.\n");
131 
132  av_free(avctx->extradata);
133  avctx->extradata = out;
134  avctx->extradata_size = total_size;
135 
136  return length_size;
137 }
138 
139 static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
140  AVCodecContext *avctx, const char *args,
141  uint8_t **poutbuf, int *poutbuf_size,
142  const uint8_t *buf, int buf_size,
143  int keyframe)
144 {
145  H264BSFContext *ctx = bsfc->priv_data;
146  int i;
147  uint8_t unit_type;
148  int32_t nal_size;
149  uint32_t cumul_size = 0;
150  const uint8_t *buf_end = buf + buf_size;
151  int ret = 0;
152 
153  /* nothing to filter */
154  if (!avctx->extradata || avctx->extradata_size < 6) {
155  *poutbuf = (uint8_t *)buf;
156  *poutbuf_size = buf_size;
157  return 0;
158  }
159 
160  /* retrieve sps and pps NAL units from extradata */
161  if (!ctx->extradata_parsed) {
162  ret = h264_extradata_to_annexb(ctx, avctx, FF_INPUT_BUFFER_PADDING_SIZE);
163  if (ret < 0)
164  return ret;
165  ctx->length_size = ret;
166  ctx->new_idr = 1;
167  ctx->idr_sps_seen = 0;
168  ctx->idr_pps_seen = 0;
169  ctx->extradata_parsed = 1;
170  }
171 
172  *poutbuf_size = 0;
173  *poutbuf = NULL;
174  do {
175  ret= AVERROR(EINVAL);
176  if (buf + ctx->length_size > buf_end)
177  goto fail;
178 
179  for (nal_size = 0, i = 0; i<ctx->length_size; i++)
180  nal_size = (nal_size << 8) | buf[i];
181 
182  buf += ctx->length_size;
183  unit_type = *buf & 0x1f;
184 
185  if (buf + nal_size > buf_end || nal_size < 0)
186  goto fail;
187 
188  if (unit_type == 7)
189  ctx->idr_sps_seen = ctx->new_idr = 1;
190  else if (unit_type == 8) {
191  ctx->idr_pps_seen = ctx->new_idr = 1;
192  /* if SPS has not been seen yet, prepend the AVCC one to PPS */
193  if (!ctx->idr_sps_seen) {
194  if (ctx->sps_offset == -1)
195  av_log(avctx, AV_LOG_WARNING, "SPS not present in the stream, nor in AVCC, stream may be unreadable\n");
196  else {
197  if ((ret = alloc_and_copy(poutbuf, poutbuf_size,
198  avctx->extradata + ctx->sps_offset,
199  ctx->pps_offset != -1 ? ctx->pps_offset : avctx->extradata_size - ctx->sps_offset,
200  buf, nal_size)) < 0)
201  goto fail;
202  ctx->idr_sps_seen = 1;
203  goto next_nal;
204  }
205  }
206  }
207 
208  /* if this is a new IDR picture following an IDR picture, reset the idr flag.
209  * Just check first_mb_in_slice to be 0 as this is the simplest solution.
210  * This could be checking idr_pic_id instead, but would complexify the parsing. */
211  if (!ctx->new_idr && unit_type == 5 && (buf[1] & 0x80))
212  ctx->new_idr = 1;
213 
214  /* prepend only to the first type 5 NAL unit of an IDR picture, if no sps/pps are already present */
215  if (ctx->new_idr && unit_type == 5 && !ctx->idr_sps_seen && !ctx->idr_pps_seen) {
216  if ((ret=alloc_and_copy(poutbuf, poutbuf_size,
217  avctx->extradata, avctx->extradata_size,
218  buf, nal_size)) < 0)
219  goto fail;
220  ctx->new_idr = 0;
221  /* if only SPS has been seen, also insert PPS */
222  } else if (ctx->new_idr && unit_type == 5 && ctx->idr_sps_seen && !ctx->idr_pps_seen) {
223  if (ctx->pps_offset == -1) {
224  av_log(avctx, AV_LOG_WARNING, "PPS not present in the stream, nor in AVCC, stream may be unreadable\n");
225  if ((ret = alloc_and_copy(poutbuf, poutbuf_size,
226  NULL, 0, buf, nal_size)) < 0)
227  goto fail;
228  } else if ((ret = alloc_and_copy(poutbuf, poutbuf_size,
229  avctx->extradata + ctx->pps_offset, avctx->extradata_size - ctx->pps_offset,
230  buf, nal_size)) < 0)
231  goto fail;
232  } else {
233  if ((ret=alloc_and_copy(poutbuf, poutbuf_size,
234  NULL, 0, buf, nal_size)) < 0)
235  goto fail;
236  if (!ctx->new_idr && unit_type == 1) {
237  ctx->new_idr = 1;
238  ctx->idr_sps_seen = 0;
239  ctx->idr_pps_seen = 0;
240  }
241  }
242 
243 next_nal:
244  buf += nal_size;
245  cumul_size += nal_size + ctx->length_size;
246  } while (cumul_size < buf_size);
247 
248  return 1;
249 
250 fail:
251  av_freep(poutbuf);
252  *poutbuf_size = 0;
253  return ret;
254 }
255 
256 AVBitStreamFilter ff_h264_mp4toannexb_bsf = {
257  .name = "h264_mp4toannexb",
258  .priv_data_size = sizeof(H264BSFContext),
259  .filter = h264_mp4toannexb_filter,
260 };
Generated on Sun Mar 8 2015 02:34:52 for FFmpeg by   doxygen 1.8.2