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 "rtpdec_formats.h"

23 #include "internal.h"

24 #include "libavutil/avstring.h"

25 #include "libavcodec/get_bits.h"

27 struct PayloadContext {

28 AVIOContext *dyn_buf;

29 uint8_t *buf;

30 int pos, len;

31 uint32_t timestamp;

32 };

34 static PayloadContext *latm_new_context(void)

35 {

36 return av_mallocz(sizeof(PayloadContext));

37 }

39 static void latm_free_context(PayloadContext *data)

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 }

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

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;

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);

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);

73 if (!(flags & RTP_FLAG_MARKER))

74 return AVERROR(EAGAIN);

75 av_free(data->buf);

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

77 data->dyn_buf = NULL;

78 data->pos = 0;

79 }

81 if (!data->buf) {

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

83 return AVERROR(EIO);

84 }

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 }

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 */

114 config = av_mallocz(len + FF_INPUT_BUFFER_PADDING_SIZE);

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

145 static int parse_fmtp(AVFormatContext *s,

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)

158 avpriv_request_sample(s,

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

179 RTPDynamicProtocolHandler ff_mp4a_latm_dynamic_handler = {

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 };

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