FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
rtpdec_latm.c
Go to the documentation of this file.
1 /*
2  * RTP Depacketization of MP4A-LATM, RFC 3016
3  * Copyright (c) 2010 Martin Storsjo
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 "rtpdec_formats.h"
23 #include "internal.h"
24 #include "libavutil/avstring.h"
25 #include "libavcodec/get_bits.h"
26 
27 struct PayloadContext {
29  uint8_t *buf;
30  int pos, len;
31  uint32_t timestamp;
32 };
33 
35 {
36  return av_mallocz(sizeof(PayloadContext));
37 }
38 
40 {
41  if (!data)
42  return;
43  if (data->dyn_buf) {
44  uint8_t *p;
45  avio_close_dyn_buf(data->dyn_buf, &p);
46  av_free(p);
47  }
48  av_freep(&data->buf);
49  av_free(data);
50 }
51 
53  AVStream *st, AVPacket *pkt, uint32_t *timestamp,
54  const uint8_t *buf, int len, uint16_t seq,
55  int flags)
56 {
57  int ret, cur_len;
58 
59  if (buf) {
60  if (!data->dyn_buf || data->timestamp != *timestamp) {
61  av_freep(&data->buf);
62  if (data->dyn_buf)
63  avio_close_dyn_buf(data->dyn_buf, &data->buf);
64  data->dyn_buf = NULL;
65  av_freep(&data->buf);
66 
67  data->timestamp = *timestamp;
68  if ((ret = avio_open_dyn_buf(&data->dyn_buf)) < 0)
69  return ret;
70  }
71  avio_write(data->dyn_buf, buf, len);
72 
73  if (!(flags & RTP_FLAG_MARKER))
74  return AVERROR(EAGAIN);
75  av_freep(&data->buf);
76  data->len = avio_close_dyn_buf(data->dyn_buf, &data->buf);
77  data->dyn_buf = NULL;
78  data->pos = 0;
79  }
80 
81  if (!data->buf) {
82  av_log(ctx, AV_LOG_ERROR, "No data available yet\n");
83  return AVERROR(EIO);
84  }
85 
86  cur_len = 0;
87  while (data->pos < data->len) {
88  uint8_t val = data->buf[data->pos++];
89  cur_len += val;
90  if (val != 0xff)
91  break;
92  }
93  if (data->pos + cur_len > data->len) {
94  av_log(ctx, AV_LOG_ERROR, "Malformed LATM packet\n");
95  return AVERROR(EIO);
96  }
97 
98  if ((ret = av_new_packet(pkt, cur_len)) < 0)
99  return ret;
100  memcpy(pkt->data, data->buf + data->pos, cur_len);
101  data->pos += cur_len;
102  pkt->stream_index = st->index;
103  return data->pos < data->len;
104 }
105 
106 static int parse_fmtp_config(AVStream *st, char *value)
107 {
108  int len = ff_hex_to_data(NULL, value), i, ret = 0;
109  GetBitContext gb;
110  uint8_t *config;
111  int audio_mux_version, same_time_framing, num_programs, num_layers;
112 
113  /* Pad this buffer, too, to avoid out of bounds reads with get_bits below */
115  if (!config)
116  return AVERROR(ENOMEM);
117  ff_hex_to_data(config, value);
118  init_get_bits(&gb, config, len*8);
119  audio_mux_version = get_bits(&gb, 1);
120  same_time_framing = get_bits(&gb, 1);
121  skip_bits(&gb, 6); /* num_sub_frames */
122  num_programs = get_bits(&gb, 4);
123  num_layers = get_bits(&gb, 3);
124  if (audio_mux_version != 0 || same_time_framing != 1 || num_programs != 0 ||
125  num_layers != 0) {
126  av_log(NULL, AV_LOG_WARNING, "Unsupported LATM config (%d,%d,%d,%d)\n",
127  audio_mux_version, same_time_framing,
128  num_programs, num_layers);
129  ret = AVERROR_PATCHWELCOME;
130  goto end;
131  }
132  av_freep(&st->codec->extradata);
133  if (ff_alloc_extradata(st->codec, (get_bits_left(&gb) + 7)/8)) {
134  ret = AVERROR(ENOMEM);
135  goto end;
136  }
137  for (i = 0; i < st->codec->extradata_size; i++)
138  st->codec->extradata[i] = get_bits(&gb, 8);
139 
140 end:
141  av_free(config);
142  return ret;
143 }
144 
146  AVStream *stream, PayloadContext *data,
147  char *attr, char *value)
148 {
149  int res;
150 
151  if (!strcmp(attr, "config")) {
152  res = parse_fmtp_config(stream, value);
153  if (res < 0)
154  return res;
155  } else if (!strcmp(attr, "cpresent")) {
156  int cpresent = atoi(value);
157  if (cpresent != 0)
159  "RTP MP4A-LATM with in-band configuration");
160  }
161 
162  return 0;
163 }
164 
165 static int latm_parse_sdp_line(AVFormatContext *s, int st_index,
166  PayloadContext *data, const char *line)
167 {
168  const char *p;
169 
170  if (st_index < 0)
171  return 0;
172 
173  if (av_strstart(line, "fmtp:", &p))
174  return ff_parse_fmtp(s, s->streams[st_index], data, p, parse_fmtp);
175 
176  return 0;
177 }
178 
180  .enc_name = "MP4A-LATM",
181  .codec_type = AVMEDIA_TYPE_AUDIO,
182  .codec_id = AV_CODEC_ID_AAC,
183  .parse_sdp_a_line = latm_parse_sdp_line,
184  .alloc = latm_new_context,
185  .free = latm_free_context,
186  .parse_packet = latm_parse_packet
187 };