FFmpeg: libavformat/rtpdec_latm.c Source File

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libavformat

rtpdec_latm.c

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1 /*

2 * RTP Depacketization of MP4A-LATM, RFC 3016

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 */

22 #include "avio_internal.h"

23 #include "rtpdec_formats.h"

24 #include "internal.h"

25 #include "libavutil/avstring.h"

26 #include "libavcodec/get_bits.h"

28 struct PayloadContext {

29 AVIOContext *dyn_buf;

30 uint8_t *buf;

31 int pos, len;

32 uint32_t timestamp;

33 };

35 static void latm_close_context(PayloadContext *data)

36 {

37 ffio_free_dyn_buf(&data->dyn_buf);

38 av_freep(&data->buf);

39 }

41 static int latm_parse_packet(AVFormatContext *ctx, PayloadContext *data,

42 AVStream *st, AVPacket *pkt, uint32_t *timestamp,

43 const uint8_t *buf, int len, uint16_t seq,

44 int flags)

45 {

46 int ret, cur_len;

48 if (buf) {

49 if (!data->dyn_buf || data->timestamp != *timestamp) {

50 av_freep(&data->buf);

51 ffio_free_dyn_buf(&data->dyn_buf);

53 data->timestamp = *timestamp;

54 if ((ret = avio_open_dyn_buf(&data->dyn_buf)) < 0)

55 return ret;

56 }

57 avio_write(data->dyn_buf, buf, len);

59 if (!(flags & RTP_FLAG_MARKER))

60 return AVERROR(EAGAIN);

61 av_freep(&data->buf);

62 data->len = avio_close_dyn_buf(data->dyn_buf, &data->buf);

63 data->dyn_buf = NULL;

64 data->pos = 0;

65 }

67 if (!data->buf) {

68 av_log(ctx, AV_LOG_ERROR, "No data available yet\n");

69 return AVERROR(EIO);

70 }

72 cur_len = 0;

73 while (data->pos < data->len) {

74 uint8_t val = data->buf[data->pos++];

75 cur_len += val;

76 if (val != 0xff)

77 break;

78 }

79 if (data->pos + cur_len > data->len) {

80 av_log(ctx, AV_LOG_ERROR, "Malformed LATM packet\n");

81 return AVERROR(EIO);

82 }

84 if ((ret = av_new_packet(pkt, cur_len)) < 0)

85 return ret;

86 memcpy(pkt->data, data->buf + data->pos, cur_len);

87 data->pos += cur_len;

88 pkt->stream_index = st->index;

89 return data->pos < data->len;

90 }

92 static int parse_fmtp_config(AVStream *st, const char *value)

93 {

94 int len = ff_hex_to_data(NULL, value), i, ret = 0;

95 GetBitContext gb;

96 uint8_t *config;

97 int audio_mux_version, same_time_framing, num_programs, num_layers;

99 /* Pad this buffer, too, to avoid out of bounds reads with get_bits below */

100 config = av_mallocz(len + FF_INPUT_BUFFER_PADDING_SIZE);

101 if (!config)

102 return AVERROR(ENOMEM);

103 ff_hex_to_data(config, value);

104 init_get_bits(&gb, config, len*8);

105 audio_mux_version = get_bits(&gb, 1);

106 same_time_framing = get_bits(&gb, 1);

107 skip_bits(&gb, 6); /* num_sub_frames */

108 num_programs = get_bits(&gb, 4);

109 num_layers = get_bits(&gb, 3);

110 if (audio_mux_version != 0 || same_time_framing != 1 || num_programs != 0 ||

111 num_layers != 0) {

112 av_log(NULL, AV_LOG_WARNING, "Unsupported LATM config (%d,%d,%d,%d)\n",

113 audio_mux_version, same_time_framing,

114 num_programs, num_layers);

115 ret = AVERROR_PATCHWELCOME;

116 goto end;

117 }

118 av_freep(&st->codec->extradata);

119 if (ff_alloc_extradata(st->codec, (get_bits_left(&gb) + 7)/8)) {

120 ret = AVERROR(ENOMEM);

121 goto end;

122 }

123 for (i = 0; i < st->codec->extradata_size; i++)

124 st->codec->extradata[i] = get_bits(&gb, 8);

125

126 end:

127 av_free(config);

128 return ret;

129 }

130

131 static int parse_fmtp(AVFormatContext *s,

132 AVStream *stream, PayloadContext *data,

133 const char *attr, const char *value)

134 {

135 int res;

136

137 if (!strcmp(attr, "config")) {

138 res = parse_fmtp_config(stream, value);

139 if (res < 0)

140 return res;

141 } else if (!strcmp(attr, "cpresent")) {

142 int cpresent = atoi(value);

143 if (cpresent != 0)

144 avpriv_request_sample(s,

145 "RTP MP4A-LATM with in-band configuration");

146 }

147

148 return 0;

149 }

150

151 static int latm_parse_sdp_line(AVFormatContext *s, int st_index,

152 PayloadContext *data, const char *line)

153 {

154 const char *p;

155

156 if (st_index < 0)

157 return 0;

158

159 if (av_strstart(line, "fmtp:", &p))

160 return ff_parse_fmtp(s, s->streams[st_index], data, p, parse_fmtp);

161

162 return 0;

163 }

164

165 RTPDynamicProtocolHandler ff_mp4a_latm_dynamic_handler = {

166 .enc_name = "MP4A-LATM",

167 .codec_type = AVMEDIA_TYPE_AUDIO,

168 .codec_id = AV_CODEC_ID_AAC,

169 .priv_data_size = sizeof(PayloadContext),

170 .parse_sdp_a_line = latm_parse_sdp_line,

171 .close = latm_close_context,

172 .parse_packet = latm_parse_packet,

173 };

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