FFmpeg: libavformat/mpc8.c Source File

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libavformat

mpc8.c

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1 /*

2 * Musepack SV8 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/get_bits.h"

23 #include "libavcodec/unary.h"

24 #include "apetag.h"

25 #include "avformat.h"

26 #include "internal.h"

27 #include "avio_internal.h"

29 /// Two-byte MPC tag

30 #define MKMPCTAG(a, b) (a | (b << 8))

32 #define TAG_MPCK MKTAG('M','P','C','K')

34 /// Reserved MPC tags

35 enum MPCPacketTags{

36 TAG_STREAMHDR = MKMPCTAG('S','H'),

37 TAG_STREAMEND = MKMPCTAG('S','E'),

39 TAG_AUDIOPACKET = MKMPCTAG('A','P'),

41 TAG_SEEKTBLOFF = MKMPCTAG('S','O'),

42 TAG_SEEKTABLE = MKMPCTAG('S','T'),

44 TAG_REPLAYGAIN = MKMPCTAG('R','G'),

45 TAG_ENCINFO = MKMPCTAG('E','I'),

46 };

48 static const int mpc8_rate[8] = { 44100, 48000, 37800, 32000, -1, -1, -1, -1 };

50 typedef struct {

51 int ver;

52 int64_t header_pos;

53 int64_t samples;

55 int64_t apetag_start;

56 } MPCContext;

58 static inline int64_t bs_get_v(const uint8_t **bs)

59 {

60 int64_t v = 0;

61 int br = 0;

62 int c;

64 do {

65 c = **bs; (*bs)++;

66 v <<= 7;

67 v |= c & 0x7F;

68 br++;

69 if (br > 10)

70 return -1;

71 } while (c & 0x80);

73 return v - br;

74 }

76 static int mpc8_probe(AVProbeData *p)

77 {

78 const uint8_t *bs = p->buf + 4;

79 const uint8_t *bs_end = bs + p->buf_size;

80 int64_t size;

82 if (p->buf_size < 16)

83 return 0;

84 if (AV_RL32(p->buf) != TAG_MPCK)

85 return 0;

86 while (bs < bs_end + 3) {

87 int header_found = (bs[0] == 'S' && bs[1] == 'H');

88 if (bs[0] < 'A' || bs[0] > 'Z' || bs[1] < 'A' || bs[1] > 'Z')

89 return 0;

90 bs += 2;

91 size = bs_get_v(&bs);

92 if (size < 2)

93 return 0;

94 if (bs + size - 2 >= bs_end)

95 return AVPROBE_SCORE_MAX / 4 - 1; //seems to be valid MPC but no header yet

96 if (header_found) {

97 if (size < 11 || size > 28)

98 return 0;

99 if (!AV_RL32(bs)) //zero CRC is invalid

100 return 0;

101 return AVPROBE_SCORE_MAX;

102 } else {

103 bs += size - 2;

104 }

105 }

106 return 0;

107 }

108

109 static inline int64_t gb_get_v(GetBitContext *gb)

110 {

111 int64_t v = 0;

112 int bits = 0;

113 while(get_bits1(gb) && bits < 64-7){

114 v <<= 7;

115 v |= get_bits(gb, 7);

116 bits += 7;

117 }

118 v <<= 7;

119 v |= get_bits(gb, 7);

120

121 return v;

122 }

123

124 static void mpc8_get_chunk_header(AVIOContext *pb, int *tag, int64_t *size)

125 {

126 int64_t pos;

127 pos = avio_tell(pb);

128 *tag = avio_rl16(pb);

129 *size = ffio_read_varlen(pb);

130 *size -= avio_tell(pb) - pos;

131 }

132

133 static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)

134 {

135 MPCContext *c = s->priv_data;

136 int tag;

137 int64_t size, pos, ppos[2];

138 uint8_t *buf;

139 int i, t, seekd;

140 GetBitContext gb;

141

142 avio_seek(s->pb, off, SEEK_SET);

143 mpc8_get_chunk_header(s->pb, &tag, &size);

144 if(tag != TAG_SEEKTABLE){

145 av_log(s, AV_LOG_ERROR, "No seek table at given position\n");

146 return;

147 }

148 if (size > INT_MAX/10 || size<=0) {

149 av_log(s, AV_LOG_ERROR, "Seek table size is invalid\n");

150 return;

151 }

152 if(!(buf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE)))

153 return;

154 avio_read(s->pb, buf, size);

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

156 size = gb_get_v(&gb);

157 if(size > UINT_MAX/4 || size > c->samples/1152){

158 av_log(s, AV_LOG_ERROR, "Seek table is too big\n");

159 return;

160 }

161 seekd = get_bits(&gb, 4);

162 for(i = 0; i < 2; i++){

163 pos = gb_get_v(&gb) + c->header_pos;

164 ppos[1 - i] = pos;

165 av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);

166 }

167 for(; i < size; i++){

168 t = get_unary(&gb, 1, 33) << 12;

169 t += get_bits(&gb, 12);

170 if(t & 1)

171 t = -(t & ~1);

172 pos = (t >> 1) + ppos[0]*2 - ppos[1];

173 av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME);

174 ppos[1] = ppos[0];

175 ppos[0] = pos;

176 }

177 av_free(buf);

178 }

179

180 static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, int64_t size)

181 {

182 AVIOContext *pb = s->pb;

183 int64_t pos, off;

184

185 switch(tag){

186 case TAG_SEEKTBLOFF:

187 pos = avio_tell(pb) + size;

188 off = ffio_read_varlen(pb);

189 mpc8_parse_seektable(s, chunk_pos + off);

190 avio_seek(pb, pos, SEEK_SET);

191 break;

192 default:

193 avio_skip(pb, size);

194 }

195 }

196

197 static int mpc8_read_header(AVFormatContext *s)

198 {

199 MPCContext *c = s->priv_data;

200 AVIOContext *pb = s->pb;

201 AVStream *st;

202 int tag = 0;

203 int64_t size, pos;

204

205 c->header_pos = avio_tell(pb);

206 if(avio_rl32(pb) != TAG_MPCK){

207 av_log(s, AV_LOG_ERROR, "Not a Musepack8 file\n");

208 return AVERROR_INVALIDDATA;

209 }

210

211 while(!url_feof(pb)){

212 pos = avio_tell(pb);

213 mpc8_get_chunk_header(pb, &tag, &size);

214 if(tag == TAG_STREAMHDR)

215 break;

216 mpc8_handle_chunk(s, tag, pos, size);

217 }

218 if(tag != TAG_STREAMHDR){

219 av_log(s, AV_LOG_ERROR, "Stream header not found\n");

220 return AVERROR_INVALIDDATA;

221 }

222 pos = avio_tell(pb);

223 avio_skip(pb, 4); //CRC

224 c->ver = avio_r8(pb);

225 if(c->ver != 8){

226 av_log(s, AV_LOG_ERROR, "Unknown stream version %d\n", c->ver);

227 return AVERROR_PATCHWELCOME;

228 }

229 c->samples = ffio_read_varlen(pb);

230 ffio_read_varlen(pb); //silence samples at the beginning

231

232 st = avformat_new_stream(s, NULL);

233 if (!st)

234 return AVERROR(ENOMEM);

235 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

236 st->codec->codec_id = AV_CODEC_ID_MUSEPACK8;

237 st->codec->bits_per_coded_sample = 16;

238

239 st->codec->extradata_size = 2;

240 st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);

241 avio_read(pb, st->codec->extradata, st->codec->extradata_size);

242

243 st->codec->channels = (st->codec->extradata[1] >> 4) + 1;

244 st->codec->sample_rate = mpc8_rate[st->codec->extradata[0] >> 5];

245 avpriv_set_pts_info(st, 32, 1152 << (st->codec->extradata[1]&3)*2, st->codec->sample_rate);

246 st->start_time = 0;

247 st->duration = c->samples / (1152 << (st->codec->extradata[1]&3)*2);

248 size -= avio_tell(pb) - pos;

249 if (size > 0)

250 avio_skip(pb, size);

251

252 if (pb->seekable) {

253 int64_t pos = avio_tell(s->pb);

254 c->apetag_start = ff_ape_parse_tag(s);

255 avio_seek(s->pb, pos, SEEK_SET);

256 }

257

258 return 0;

259 }

260

261 static int mpc8_read_packet(AVFormatContext *s, AVPacket *pkt)

262 {

263 MPCContext *c = s->priv_data;

264 int tag;

265 int64_t pos, size;

266

267 while(!url_feof(s->pb)){

268 pos = avio_tell(s->pb);

269

270 /* don't return bogus packets with the ape tag data */

271 if (c->apetag_start && pos >= c->apetag_start)

272 return AVERROR_EOF;

273

274 mpc8_get_chunk_header(s->pb, &tag, &size);

275 if (size < 0)

276 return -1;

277 if(tag == TAG_AUDIOPACKET){

278 if(av_get_packet(s->pb, pkt, size) < 0)

279 return AVERROR(ENOMEM);

280 pkt->stream_index = 0;

281 pkt->duration = 1;

282 return 0;

283 }

284 if(tag == TAG_STREAMEND)

285 return AVERROR(EIO);

286 mpc8_handle_chunk(s, tag, pos, size);

287 }

288 return AVERROR_EOF;

289 }

290

291 static int mpc8_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)

292 {

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

294 int index = av_index_search_timestamp(st, timestamp, flags);

295

296 if(index < 0) return -1;

297 if (avio_seek(s->pb, st->index_entries[index].pos, SEEK_SET) < 0)

298 return -1;

299 ff_update_cur_dts(s, st, st->index_entries[index].timestamp);

300 return 0;

301 }

302

303

304 AVInputFormat ff_mpc8_demuxer = {

305 .name = "mpc8",

306 .long_name = NULL_IF_CONFIG_SMALL("Musepack SV8"),

307 .priv_data_size = sizeof(MPCContext),

308 .read_probe = mpc8_probe,

309 .read_header = mpc8_read_header,

310 .read_packet = mpc8_read_packet,

311 .read_seek = mpc8_read_seek,

312 };

Generated on Sat May 25 2013 03:58:37 for FFmpeg by doxygen 1.8.2