FFmpeg: libavformat/rtpdec_mpeg4.c Source File

FFmpeg
rtpdec_mpeg4.c
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1 /*
2  * Common code for the RTP depacketization of MPEG-4 formats.
3  * Copyright (c) 2010 Fabrice Bellard
4  * Romain Degez
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * @brief MPEG4 / RTP Code
26  * @author Fabrice Bellard
27  * @author Romain Degez
28  */
29 
30 #include "rtpdec_formats.h"
31 #include "internal.h"
32 #include "libavutil/attributes.h"
33 #include "libavutil/avstring.h"
34 #include "libavcodec/get_bits.h"
35 
36 /** Structure listing useful vars to parse RTP packet payload */
37 struct PayloadContext {
38   int sizelength;
39   int indexlength;
40   int indexdeltalength;
41   int profile_level_id;
42   int streamtype;
43   int objecttype;
44   char *mode;
45 
46  /** mpeg 4 AU headers */
47   struct AUHeaders {
48   int size;
49   int index;
50   int cts_flag;
51   int cts;
52   int dts_flag;
53   int dts;
54   int rap_flag;
55   int streamstate;
56  } *au_headers;
57   int au_headers_allocated;
58   int nb_au_headers;
59   int au_headers_length_bytes;
60   int cur_au_index;
61 
62   uint8_t buf[RTP_MAX_PACKET_LENGTH];
63   int buf_pos, buf_size;
64 };
65 
66  typedef struct {
67   const char *str;
68   uint16_t type;
69   uint32_t offset;
70 } AttrNameMap;
71 
72 /* All known fmtp parameters and the corresponding RTPAttrTypeEnum */
73  #define ATTR_NAME_TYPE_INT 0
74  #define ATTR_NAME_TYPE_STR 1
75  static const AttrNameMap attr_names[] = {
76  { "SizeLength", ATTR_NAME_TYPE_INT,
77  offsetof(PayloadContext, sizelength) },
78  { "IndexLength", ATTR_NAME_TYPE_INT,
79  offsetof(PayloadContext, indexlength) },
80  { "IndexDeltaLength", ATTR_NAME_TYPE_INT,
81  offsetof(PayloadContext, indexdeltalength) },
82  { "profile-level-id", ATTR_NAME_TYPE_INT,
83  offsetof(PayloadContext, profile_level_id) },
84  { "StreamType", ATTR_NAME_TYPE_INT,
85  offsetof(PayloadContext, streamtype) },
86  { "mode", ATTR_NAME_TYPE_STR,
87  offsetof(PayloadContext, mode) },
88  { NULL, -1, -1 },
89 };
90 
91  static PayloadContext *new_context(void)
92 {
93  return av_mallocz(sizeof(PayloadContext));
94 }
95 
96  static void free_context(PayloadContext *data)
97 {
98  av_free(data->au_headers);
99  av_free(data->mode);
100  av_free(data);
101 }
102 
103  static int parse_fmtp_config(AVCodecContext *codec, char *value)
104 {
105  /* decode the hexa encoded parameter */
106  int len = ff_hex_to_data(NULL, value);
107  av_free(codec->extradata);
108  codec->extradata = av_mallocz(len + FF_INPUT_BUFFER_PADDING_SIZE);
109  if (!codec->extradata)
110  return AVERROR(ENOMEM);
111  codec->extradata_size = len;
112  ff_hex_to_data(codec->extradata, value);
113  return 0;
114 }
115 
116  static int rtp_parse_mp4_au(PayloadContext *data, const uint8_t *buf, int len)
117 {
118  int au_headers_length, au_header_size, i;
119  GetBitContext getbitcontext;
120 
121  if (len < 2)
122  return AVERROR_INVALIDDATA;
123 
124  /* decode the first 2 bytes where the AUHeader sections are stored
125  length in bits */
126  au_headers_length = AV_RB16(buf);
127 
128  if (au_headers_length > RTP_MAX_PACKET_LENGTH)
129  return -1;
130 
131  data->au_headers_length_bytes = (au_headers_length + 7) / 8;
132 
133  /* skip AU headers length section (2 bytes) */
134  buf += 2;
135  len -= 2;
136 
137  if (len < data->au_headers_length_bytes)
138  return AVERROR_INVALIDDATA;
139 
140  init_get_bits(&getbitcontext, buf, data->au_headers_length_bytes * 8);
141 
142  /* XXX: Wrong if optional additional sections are present (cts, dts etc...) */
143  au_header_size = data->sizelength + data->indexlength;
144  if (au_header_size <= 0 || (au_headers_length % au_header_size != 0))
145  return -1;
146 
147  data->nb_au_headers = au_headers_length / au_header_size;
148  if (!data->au_headers || data->au_headers_allocated < data->nb_au_headers) {
149  av_free(data->au_headers);
150  data->au_headers = av_malloc(sizeof(struct AUHeaders) * data->nb_au_headers);
151  if (!data->au_headers)
152  return AVERROR(ENOMEM);
153  data->au_headers_allocated = data->nb_au_headers;
154  }
155 
156  for (i = 0; i < data->nb_au_headers; ++i) {
157  data->au_headers[i].size = get_bits_long(&getbitcontext, data->sizelength);
158  data->au_headers[i].index = get_bits_long(&getbitcontext, data->indexlength);
159  }
160 
161  return 0;
162 }
163 
164 
165 /* Follows RFC 3640 */
166  static int aac_parse_packet(AVFormatContext *ctx, PayloadContext *data,
167  AVStream *st, AVPacket *pkt, uint32_t *timestamp,
168  const uint8_t *buf, int len, uint16_t seq,
169  int flags)
170 {
171  int ret;
172 
173  if (!buf) {
174  if (data->cur_au_index > data->nb_au_headers)
175  return AVERROR_INVALIDDATA;
176  if (data->buf_size - data->buf_pos < data->au_headers[data->cur_au_index].size)
177  return AVERROR_INVALIDDATA;
178  if ((ret = av_new_packet(pkt, data->au_headers[data->cur_au_index].size)) < 0)
179  return ret;
180  memcpy(pkt->data, &data->buf[data->buf_pos], data->au_headers[data->cur_au_index].size);
181  data->buf_pos += data->au_headers[data->cur_au_index].size;
182  pkt->stream_index = st->index;
183  data->cur_au_index++;
184  return data->cur_au_index < data->nb_au_headers;
185  }
186 
187  if (rtp_parse_mp4_au(data, buf, len))
188  return -1;
189 
190  buf += data->au_headers_length_bytes + 2;
191  len -= data->au_headers_length_bytes + 2;
192 
193  if (len < data->au_headers[0].size)
194  return AVERROR_INVALIDDATA;
195  if ((ret = av_new_packet(pkt, data->au_headers[0].size)) < 0)
196  return ret;
197  memcpy(pkt->data, buf, data->au_headers[0].size);
198  len -= data->au_headers[0].size;
199  buf += data->au_headers[0].size;
200  pkt->stream_index = st->index;
201 
202  if (len > 0 && data->nb_au_headers > 1) {
203  data->buf_size = FFMIN(len, sizeof(data->buf));
204  memcpy(data->buf, buf, data->buf_size);
205  data->cur_au_index = 1;
206  data->buf_pos = 0;
207  return 1;
208  }
209 
210  return 0;
211 }
212 
213  static int parse_fmtp(AVStream *stream, PayloadContext *data,
214  char *attr, char *value)
215 {
216  AVCodecContext *codec = stream->codec;
217  int res, i;
218 
219  if (!strcmp(attr, "config")) {
220  res = parse_fmtp_config(codec, value);
221 
222  if (res < 0)
223  return res;
224  }
225 
226  if (codec->codec_id == AV_CODEC_ID_AAC) {
227  /* Looking for a known attribute */
228  for (i = 0; attr_names[i].str; ++i) {
229  if (!av_strcasecmp(attr, attr_names[i].str)) {
230  if (attr_names[i].type == ATTR_NAME_TYPE_INT) {
231  *(int *)((char *)data+
232  attr_names[i].offset) = atoi(value);
233  } else if (attr_names[i].type == ATTR_NAME_TYPE_STR)
234  *(char **)((char *)data+
235  attr_names[i].offset) = av_strdup(value);
236  }
237  }
238  }
239  return 0;
240 }
241 
242  static int parse_sdp_line(AVFormatContext *s, int st_index,
243  PayloadContext *data, const char *line)
244 {
245  const char *p;
246 
247  if (st_index < 0)
248  return 0;
249 
250  if (av_strstart(line, "fmtp:", &p))
251  return ff_parse_fmtp(s->streams[st_index], data, p, parse_fmtp);
252 
253  return 0;
254 }
255 
256  static av_cold int init_video(AVFormatContext *s, int st_index,
257  PayloadContext *data)
258 {
259  if (st_index < 0)
260  return 0;
261  s->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL;
262  return 0;
263 }
264 
265  RTPDynamicProtocolHandler ff_mp4v_es_dynamic_handler = {
266  .enc_name = "MP4V-ES",
267  .codec_type = AVMEDIA_TYPE_VIDEO,
268  .codec_id = AV_CODEC_ID_MPEG4,
269  .init = init_video,
270  .parse_sdp_a_line = parse_sdp_line,
271 };
272 
273  RTPDynamicProtocolHandler ff_mpeg4_generic_dynamic_handler = {
274  .enc_name = "mpeg4-generic",
275  .codec_type = AVMEDIA_TYPE_AUDIO,
276  .codec_id = AV_CODEC_ID_AAC,
277  .parse_sdp_a_line = parse_sdp_line,
278  .alloc = new_context,
279  .free = free_context,
280  .parse_packet = aac_parse_packet
281 };
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