FFmpeg: libavformat/flacdec.c Source File

FFmpeg

[フレーム]

libavformat

flacdec.c

Go to the documentation of this file.

1 /*

2 * Raw FLAC demuxer

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 "libavcodec/flac.h"

23 #include "avformat.h"

24 #include "flac_picture.h"

25 #include "internal.h"

26 #include "rawdec.h"

27 #include "oggdec.h"

28 #include "vorbiscomment.h"

29 #include "replaygain.h"

31 static int flac_read_header(AVFormatContext *s)

32 {

33 int ret, metadata_last=0, metadata_type, metadata_size, found_streaminfo=0;

34 uint8_t header[4];

35 uint8_t *buffer=NULL;

36 AVStream *st = avformat_new_stream(s, NULL);

37 if (!st)

38 return AVERROR(ENOMEM);

39 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

40 st->codec->codec_id = AV_CODEC_ID_FLAC;

41 st->need_parsing = AVSTREAM_PARSE_FULL_RAW;

42 /* the parameters will be extracted from the compressed bitstream */

44 /* if fLaC marker is not found, assume there is no header */

45 if (avio_rl32(s->pb) != MKTAG('f','L','a','C')) {

46 avio_seek(s->pb, -4, SEEK_CUR);

47 return 0;

48 }

50 /* process metadata blocks */

51 while (!avio_feof(s->pb) && !metadata_last) {

52 avio_read(s->pb, header, 4);

53 flac_parse_block_header(header, &metadata_last, &metadata_type,

54 &metadata_size);

55 switch (metadata_type) {

56 /* allocate and read metadata block for supported types */

57 case FLAC_METADATA_TYPE_STREAMINFO:

58 case FLAC_METADATA_TYPE_CUESHEET:

59 case FLAC_METADATA_TYPE_PICTURE:

60 case FLAC_METADATA_TYPE_VORBIS_COMMENT:

61 buffer = av_mallocz(metadata_size + FF_INPUT_BUFFER_PADDING_SIZE);

62 if (!buffer) {

63 return AVERROR(ENOMEM);

64 }

65 if (avio_read(s->pb, buffer, metadata_size) != metadata_size) {

66 RETURN_ERROR(AVERROR(EIO));

67 }

68 break;

69 /* skip metadata block for unsupported types */

70 default:

71 ret = avio_skip(s->pb, metadata_size);

72 if (ret < 0)

73 return ret;

74 }

76 if (metadata_type == FLAC_METADATA_TYPE_STREAMINFO) {

77 uint32_t samplerate;

78 uint64_t samples;

80 /* STREAMINFO can only occur once */

81 if (found_streaminfo) {

82 RETURN_ERROR(AVERROR_INVALIDDATA);

83 }

84 if (metadata_size != FLAC_STREAMINFO_SIZE) {

85 RETURN_ERROR(AVERROR_INVALIDDATA);

86 }

87 found_streaminfo = 1;

88 st->codec->extradata = buffer;

89 st->codec->extradata_size = metadata_size;

90 buffer = NULL;

92 /* get sample rate and sample count from STREAMINFO header;

93 * other parameters will be extracted by the parser */

94 samplerate = AV_RB24(st->codec->extradata + 10) >> 4;

95 samples = (AV_RB64(st->codec->extradata + 13) >> 24) & ((1ULL << 36) - 1);

97 /* set time base and duration */

98 if (samplerate > 0) {

99 avpriv_set_pts_info(st, 64, 1, samplerate);

100 if (samples > 0)

101 st->duration = samples;

102 }

103 } else if (metadata_type == FLAC_METADATA_TYPE_CUESHEET) {

104 uint8_t isrc[13];

105 uint64_t start;

106 const uint8_t *offset;

107 int i, chapters, track, ti;

108 if (metadata_size < 431)

109 RETURN_ERROR(AVERROR_INVALIDDATA);

110 offset = buffer + 395;

111 chapters = bytestream_get_byte(&offset) - 1;

112 if (chapters <= 0)

113 RETURN_ERROR(AVERROR_INVALIDDATA);

114 for (i = 0; i < chapters; i++) {

115 if (offset + 36 - buffer > metadata_size)

116 RETURN_ERROR(AVERROR_INVALIDDATA);

117 start = bytestream_get_be64(&offset);

118 track = bytestream_get_byte(&offset);

119 bytestream_get_buffer(&offset, isrc, 12);

120 isrc[12] = 0;

121 offset += 14;

122 ti = bytestream_get_byte(&offset);

123 if (ti <= 0) RETURN_ERROR(AVERROR_INVALIDDATA);

124 offset += ti * 12;

125 avpriv_new_chapter(s, track, st->time_base, start, AV_NOPTS_VALUE, isrc);

126 }

127 av_freep(&buffer);

128 } else if (metadata_type == FLAC_METADATA_TYPE_PICTURE) {

129 ret = ff_flac_parse_picture(s, buffer, metadata_size);

130 av_freep(&buffer);

131 if (ret < 0) {

132 av_log(s, AV_LOG_ERROR, "Error parsing attached picture.\n");

133 return ret;

134 }

135 } else {

136 /* STREAMINFO must be the first block */

137 if (!found_streaminfo) {

138 RETURN_ERROR(AVERROR_INVALIDDATA);

139 }

140 /* process supported blocks other than STREAMINFO */

141 if (metadata_type == FLAC_METADATA_TYPE_VORBIS_COMMENT) {

142 AVDictionaryEntry *chmask;

143

144 ret = ff_vorbis_comment(s, &s->metadata, buffer, metadata_size, 1);

145 if (ret < 0) {

146 av_log(s, AV_LOG_WARNING, "error parsing VorbisComment metadata\n");

147 } else if (ret > 0) {

148 s->event_flags |= AVFMT_EVENT_FLAG_METADATA_UPDATED;

149 }

150

151 /* parse the channels mask if present */

152 chmask = av_dict_get(s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", NULL, 0);

153 if (chmask) {

154 uint64_t mask = strtol(chmask->value, NULL, 0);

155 if (!mask || mask & ~0x3ffffULL) {

156 av_log(s, AV_LOG_WARNING,

157 "Invalid value of WAVEFORMATEXTENSIBLE_CHANNEL_MASK\n");

158 } else {

159 st->codec->channel_layout = mask;

160 av_dict_set(&s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", NULL, 0);

161 }

162 }

163 }

164 av_freep(&buffer);

165 }

166 }

167

168 ret = ff_replaygain_export(st, s->metadata);

169 if (ret < 0)

170 return ret;

171

172 return 0;

173

174 fail:

175 av_free(buffer);

176 return ret;

177 }

178

179 static int flac_probe(AVProbeData *p)

180 {

181 if (p->buf_size < 4 || memcmp(p->buf, "fLaC", 4))

182 return 0;

183 return AVPROBE_SCORE_EXTENSION;

184 }

185

186 static av_unused int64_t flac_read_timestamp(AVFormatContext *s, int stream_index,

187 int64_t *ppos, int64_t pos_limit)

188 {

189 AVPacket pkt, out_pkt;

190 AVStream *st = s->streams[stream_index];

191 AVCodecParserContext *parser;

192 int ret;

193 int64_t pts = AV_NOPTS_VALUE;

194

195 if (avio_seek(s->pb, *ppos, SEEK_SET) < 0)

196 return AV_NOPTS_VALUE;

197

198 av_init_packet(&pkt);

199 parser = av_parser_init(st->codec->codec_id);

200 if (!parser){

201 return AV_NOPTS_VALUE;

202 }

203 parser->flags |= PARSER_FLAG_USE_CODEC_TS;

204

205 for (;;){

206 ret = ff_raw_read_partial_packet(s, &pkt);

207 if (ret < 0){

208 if (ret == AVERROR(EAGAIN))

209 continue;

210 else

211 break;

212 }

213 av_init_packet(&out_pkt);

214 ret = av_parser_parse2(parser, st->codec,

215 &out_pkt.data, &out_pkt.size, pkt.data, pkt.size,

216 pkt.pts, pkt.dts, *ppos);

217

218 av_free_packet(&pkt);

219 if (out_pkt.size){

220 int size = out_pkt.size;

221 if (parser->pts != AV_NOPTS_VALUE){

222 // seeking may not have started from beginning of a frame

223 // calculate frame start position from next frame backwards

224 *ppos = parser->next_frame_offset - size;

225 pts = parser->pts;

226 break;

227 }

228 }

229 }

230 av_parser_close(parser);

231 return pts;

232 }

233

234 AVInputFormat ff_flac_demuxer = {

235 .name = "flac",

236 .long_name = NULL_IF_CONFIG_SMALL("raw FLAC"),

237 .read_probe = flac_probe,

238 .read_header = flac_read_header,

239 .read_packet = ff_raw_read_partial_packet,

240 .read_timestamp = flac_read_timestamp,

241 .flags = AVFMT_GENERIC_INDEX,

242 .extensions = "flac",

243 .raw_codec_id = AV_CODEC_ID_FLAC,

244 };

Generated on Sun Mar 8 2015 02:34:51 for FFmpeg by doxygen 1.8.2