rtpdec_latm.c
Go to the documentation of this file.
1 
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_free(data->buf);
49  av_free(data);
50 }
51 
53  AVStream *st, AVPacket *pkt, uint32_t *timestamp,
54  const uint8_t *buf, int len, int flags)
55 {
56  int ret, cur_len;
57 
58  if (buf) {
59  if (!data->dyn_buf || data->timestamp != *timestamp) {
60  av_freep(&data->buf);
61  if (data->dyn_buf)
62  avio_close_dyn_buf(data->dyn_buf, &data->buf);
63  data->dyn_buf = NULL;
64  av_freep(&data->buf);
65 
66  data->timestamp = *timestamp;
67  if ((ret = avio_open_dyn_buf(&data->dyn_buf)) < 0)
68  return ret;
69  }
70  avio_write(data->dyn_buf, buf, len);
71 
72  if (!(flags & RTP_FLAG_MARKER))
73  return AVERROR(EAGAIN);
74  av_free(data->buf);
75  data->len = avio_close_dyn_buf(data->dyn_buf, &data->buf);
76  data->dyn_buf = NULL;
77  data->pos = 0;
78  }
79 
80  if (!data->buf) {
81  av_log(ctx, AV_LOG_ERROR, "No data available yet\n");
82  return AVERROR(EIO);
83  }
84 
85  cur_len = 0;
86  while (data->pos < data->len) {
87  uint8_t val = data->buf[data->pos++];
88  cur_len += val;
89  if (val != 0xff)
90  break;
91  }
92  if (data->pos + cur_len > data->len) {
93  av_log(ctx, AV_LOG_ERROR, "Malformed LATM packet\n");
94  return AVERROR(EIO);
95  }
96 
97  if ((ret = av_new_packet(pkt, cur_len)) < 0)
98  return ret;
99  memcpy(pkt->data, data->buf + data->pos, cur_len);
100  data->pos += cur_len;
101  pkt->stream_index = st->index;
102  return data->pos < data->len;
103 }
104 
105 static int parse_fmtp_config(AVStream *st, char *value)
106 {
107  int len = ff_hex_to_data(NULL, value), i, ret = 0;
108  GetBitContext gb;
109  uint8_t *config;
110  int audio_mux_version, same_time_framing, num_programs, num_layers;
111 
112  /* Pad this buffer, too, to avoid out of bounds reads with get_bits below */
114  if (!config)
115  return AVERROR(ENOMEM);
116  ff_hex_to_data(config, value);
117  init_get_bits(&gb, config, len*8);
118  audio_mux_version = get_bits(&gb, 1);
119  same_time_framing = get_bits(&gb, 1);
120  skip_bits(&gb, 6); /* num_sub_frames */
121  num_programs = get_bits(&gb, 4);
122  num_layers = get_bits(&gb, 3);
123  if (audio_mux_version != 0 || same_time_framing != 1 || num_programs != 0 ||
124  num_layers != 0) {
125  av_log(NULL, AV_LOG_WARNING, "Unsupported LATM config (%d,%d,%d,%d)\n",
126  audio_mux_version, same_time_framing,
127  num_programs, num_layers);
128  ret = AVERROR_PATCHWELCOME;
129  goto end;
130  }
131  av_freep(&st->codec->extradata);
132  st->codec->extradata_size = (get_bits_left(&gb) + 7)/8;
135  if (!st->codec->extradata) {
136  ret = AVERROR(ENOMEM);
137  goto end;
138  }
139  for (i = 0; i < st->codec->extradata_size; i++)
140  st->codec->extradata[i] = get_bits(&gb, 8);
141 
142 end:
143  av_free(config);
144  return ret;
145 }
146 
147 static int parse_fmtp(AVStream *stream, PayloadContext *data,
148  char *attr, char *value)
149 {
150  int res;
151 
152  if (!strcmp(attr, "config")) {
153  res = parse_fmtp_config(stream, value);
154  if (res < 0)
155  return res;
156  } else if (!strcmp(attr, "cpresent")) {
157  int cpresent = atoi(value);
158  if (cpresent != 0)
159  av_log_missing_feature(NULL, "RTP MP4A-LATM with in-band "
160  "configuration", 1);
161  }
162 
163  return 0;
164 }
165 
166 static int latm_parse_sdp_line(AVFormatContext *s, int st_index,
167  PayloadContext *data, const char *line)
168 {
169  const char *p;
170 
171  if (av_strstart(line, "fmtp:", &p))
172  return ff_parse_fmtp(s->streams[st_index], data, p, parse_fmtp);
173 
174  return 0;
175 }
176 
178  .enc_name = "MP4A-LATM",
179  .codec_type = AVMEDIA_TYPE_AUDIO,
180  .codec_id = CODEC_ID_AAC,
181  .parse_sdp_a_line = latm_parse_sdp_line,
182  .alloc = latm_new_context,
183  .free = latm_free_context,
184  .parse_packet = latm_parse_packet
185 };