FFmpeg: libavformat/adtsenc.c Source File

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libavformat

adtsenc.c

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1 /*

2 * ADTS muxer.

4 * Mans Rullgard <mans@mansr.com>

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 */

23 #include "libavcodec/get_bits.h"

24 #include "libavcodec/put_bits.h"

25 #include "libavcodec/avcodec.h"

26 #include "libavcodec/mpeg4audio.h"

27 #include "libavutil/opt.h"

28 #include "avformat.h"

29 #include "apetag.h"

30 #include "id3v2.h"

32 #define ADTS_HEADER_SIZE 7

34 typedef struct ADTSContext {

35 AVClass *class;

36 int write_adts;

37 int objecttype;

38 int sample_rate_index;

39 int channel_conf;

40 int pce_size;

41 int apetag;

42 int id3v2tag;

43 uint8_t pce_data[MAX_PCE_SIZE];

44 } ADTSContext;

46 #define ADTS_MAX_FRAME_BYTES ((1 << 13) - 1)

48 static int adts_decode_extradata(AVFormatContext *s, ADTSContext *adts, const uint8_t *buf, int size)

49 {

50 GetBitContext gb;

51 PutBitContext pb;

52 MPEG4AudioConfig m4ac;

53 int off;

55 init_get_bits(&gb, buf, size * 8);

56 off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);

57 if (off < 0)

58 return off;

59 skip_bits_long(&gb, off);

60 adts->objecttype = m4ac.object_type - 1;

61 adts->sample_rate_index = m4ac.sampling_index;

62 adts->channel_conf = m4ac.chan_config;

64 if (adts->objecttype > 3U) {

65 av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);

66 return AVERROR_INVALIDDATA;

67 }

68 if (adts->sample_rate_index == 15) {

69 av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");

70 return AVERROR_INVALIDDATA;

71 }

72 if (get_bits(&gb, 1)) {

73 av_log(s, AV_LOG_ERROR, "960/120 MDCT window is not allowed in ADTS\n");

74 return AVERROR_INVALIDDATA;

75 }

76 if (get_bits(&gb, 1)) {

77 av_log(s, AV_LOG_ERROR, "Scalable configurations are not allowed in ADTS\n");

78 return AVERROR_INVALIDDATA;

79 }

80 if (get_bits(&gb, 1)) {

81 av_log(s, AV_LOG_ERROR, "Extension flag is not allowed in ADTS\n");

82 return AVERROR_INVALIDDATA;

83 }

84 if (!adts->channel_conf) {

85 init_put_bits(&pb, adts->pce_data, MAX_PCE_SIZE);

87 put_bits(&pb, 3, 5); //ID_PCE

88 adts->pce_size = (avpriv_copy_pce_data(&pb, &gb) + 3) / 8;

89 flush_put_bits(&pb);

90 }

92 adts->write_adts = 1;

94 return 0;

95 }

97 static int adts_write_header(AVFormatContext *s)

98 {

99 ADTSContext *adts = s->priv_data;

100 AVCodecContext *avc = s->streams[0]->codec;

101

102 if (adts->id3v2tag)

103 ff_id3v2_write_simple(s, 4, ID3v2_DEFAULT_MAGIC);

104 if (avc->extradata_size > 0)

105 return adts_decode_extradata(s, adts, avc->extradata,

106 avc->extradata_size);

107

108 return 0;

109 }

110

111 static int adts_write_frame_header(ADTSContext *ctx,

112 uint8_t *buf, int size, int pce_size)

113 {

114 PutBitContext pb;

115

116 unsigned full_frame_size = (unsigned)ADTS_HEADER_SIZE + size + pce_size;

117 if (full_frame_size > ADTS_MAX_FRAME_BYTES) {

118 av_log(NULL, AV_LOG_ERROR, "ADTS frame size too large: %u (max %d)\n",

119 full_frame_size, ADTS_MAX_FRAME_BYTES);

120 return AVERROR_INVALIDDATA;

121 }

122

123 init_put_bits(&pb, buf, ADTS_HEADER_SIZE);

124

125 /* adts_fixed_header */

126 put_bits(&pb, 12, 0xfff); /* syncword */

127 put_bits(&pb, 1, 0); /* ID */

128 put_bits(&pb, 2, 0); /* layer */

129 put_bits(&pb, 1, 1); /* protection_absent */

130 put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */

131 put_bits(&pb, 4, ctx->sample_rate_index);

132 put_bits(&pb, 1, 0); /* private_bit */

133 put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */

134 put_bits(&pb, 1, 0); /* original_copy */

135 put_bits(&pb, 1, 0); /* home */

136

137 /* adts_variable_header */

138 put_bits(&pb, 1, 0); /* copyright_identification_bit */

139 put_bits(&pb, 1, 0); /* copyright_identification_start */

140 put_bits(&pb, 13, full_frame_size); /* aac_frame_length */

141 put_bits(&pb, 11, 0x7ff); /* adts_buffer_fullness */

142 put_bits(&pb, 2, 0); /* number_of_raw_data_blocks_in_frame */

143

144 flush_put_bits(&pb);

145

146 return 0;

147 }

148

149 static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)

150 {

151 ADTSContext *adts = s->priv_data;

152 AVIOContext *pb = s->pb;

153 uint8_t buf[ADTS_HEADER_SIZE];

154

155 if (!pkt->size)

156 return 0;

157 if (adts->write_adts) {

158 int err = adts_write_frame_header(adts, buf, pkt->size,

159 adts->pce_size);

160 if (err < 0)

161 return err;

162 avio_write(pb, buf, ADTS_HEADER_SIZE);

163 if (adts->pce_size) {

164 avio_write(pb, adts->pce_data, adts->pce_size);

165 adts->pce_size = 0;

166 }

167 }

168 avio_write(pb, pkt->data, pkt->size);

169

170 return 0;

171 }

172

173 static int adts_write_trailer(AVFormatContext *s)

174 {

175 ADTSContext *adts = s->priv_data;

176

177 if (adts->apetag)

178 ff_ape_write_tag(s);

179

180 return 0;

181 }

182

183 #define ENC AV_OPT_FLAG_ENCODING_PARAM

184 #define OFFSET(obj) offsetof(ADTSContext, obj)

185 static const AVOption options[] = {

186 { "write_id3v2", "Enable ID3v2 tag writing", OFFSET(id3v2tag), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, ENC},

187 { "write_apetag", "Enable APE tag writing", OFFSET(apetag), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, ENC},

188 { NULL },

189 };

190

191 static const AVClass adts_muxer_class = {

192 .class_name = "ADTS muxer",

193 .item_name = av_default_item_name,

194 .option = options,

195 .version = LIBAVUTIL_VERSION_INT,

196 };

197

198 AVOutputFormat ff_adts_muxer = {

199 .name = "adts",

200 .long_name = NULL_IF_CONFIG_SMALL("ADTS AAC (Advanced Audio Coding)"),

201 .mime_type = "audio/aac",

202 .extensions = "aac,adts",

203 .priv_data_size = sizeof(ADTSContext),

204 .audio_codec = AV_CODEC_ID_AAC,

205 .video_codec = AV_CODEC_ID_NONE,

206 .write_header = adts_write_header,

207 .write_packet = adts_write_packet,

208 .write_trailer = adts_write_trailer,

209 .priv_class = &adts_muxer_class,

210 .flags = AVFMT_NOTIMESTAMPS,

211 };

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