FFmpeg: libavcodec/mlp_parser.c Source File

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libavcodec

mlp_parser.c

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1 /*

2 * MLP parser

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 /**

23 * @file

24 * MLP parser

25 */

27 #include <stdint.h>

29 #include "libavutil/channel_layout.h"

30 #include "libavutil/crc.h"

31 #include "libavutil/internal.h"

32 #include "get_bits.h"

33 #include "parser.h"

34 #include "mlp_parser.h"

35 #include "mlp.h"

37 static const uint8_t mlp_quants[16] = {

38 16, 20, 24, 0, 0, 0, 0, 0,

39 0, 0, 0, 0, 0, 0, 0, 0,

40 };

42 static const uint8_t mlp_channels[32] = {

43 1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,

44 5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

45 };

47 const uint64_t ff_mlp_layout[32] = {

48 AV_CH_LAYOUT_MONO,

49 AV_CH_LAYOUT_STEREO,

50 AV_CH_LAYOUT_2_1,

51 AV_CH_LAYOUT_QUAD,

52 AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY,

53 AV_CH_LAYOUT_2_1|AV_CH_LOW_FREQUENCY,

54 AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,

55 AV_CH_LAYOUT_SURROUND,

56 AV_CH_LAYOUT_4POINT0,

57 AV_CH_LAYOUT_5POINT0_BACK,

58 AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,

59 AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,

60 AV_CH_LAYOUT_5POINT1_BACK,

61 AV_CH_LAYOUT_4POINT0,

62 AV_CH_LAYOUT_5POINT0_BACK,

63 AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,

64 AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,

65 AV_CH_LAYOUT_5POINT1_BACK,

66 AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,

67 AV_CH_LAYOUT_5POINT0_BACK,

68 AV_CH_LAYOUT_5POINT1_BACK,

69 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

70 };

72 static const uint8_t thd_chancount[13] = {

73 // LR C LFE LRs LRvh LRc LRrs Cs Ts LRsd LRw Cvh LFE2

74 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 1

75 };

77 static const uint64_t thd_layout[13] = {

78 AV_CH_FRONT_LEFT|AV_CH_FRONT_RIGHT, // LR

79 AV_CH_FRONT_CENTER, // C

80 AV_CH_LOW_FREQUENCY, // LFE

81 AV_CH_SIDE_LEFT|AV_CH_SIDE_RIGHT, // LRs

82 AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT, // LRvh

83 AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER, // LRc

84 AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT, // LRrs

85 AV_CH_BACK_CENTER, // Cs

86 AV_CH_TOP_CENTER, // Ts

87 AV_CH_SURROUND_DIRECT_LEFT|AV_CH_SURROUND_DIRECT_RIGHT, // LRsd

88 AV_CH_WIDE_LEFT|AV_CH_WIDE_RIGHT, // LRw

89 AV_CH_TOP_FRONT_CENTER, // Cvh

90 AV_CH_LOW_FREQUENCY_2, // LFE2

91 };

93 static int mlp_samplerate(int in)

94 {

95 if (in == 0xF)

96 return 0;

98 return (in & 8 ? 44100 : 48000) << (in & 7) ;

99 }

100

101 static int truehd_channels(int chanmap)

102 {

103 int channels = 0, i;

104

105 for (i = 0; i < 13; i++)

106 channels += thd_chancount[i] * ((chanmap >> i) & 1);

107

108 return channels;

109 }

110

111 uint64_t ff_truehd_layout(int chanmap)

112 {

113 int i;

114 uint64_t layout = 0;

115

116 for (i = 0; i < 13; i++)

117 layout |= thd_layout[i] * ((chanmap >> i) & 1);

118

119 return layout;

120 }

121

122 /** Read a major sync info header - contains high level information about

123 * the stream - sample rate, channel arrangement etc. Most of this

124 * information is not actually necessary for decoding, only for playback.

125 * gb must be a freshly initialized GetBitContext with no bits read.

126 */

127

128 int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, GetBitContext *gb)

129 {

130 int ratebits, channel_arrangement;

131 uint16_t checksum;

132

133 av_assert1(get_bits_count(gb) == 0);

134

135 if (gb->size_in_bits < 28 << 3) {

136 av_log(log, AV_LOG_ERROR, "packet too short, unable to read major sync\n");

137 return -1;

138 }

139

140 checksum = ff_mlp_checksum16(gb->buffer, 26);

141 if (checksum != AV_RL16(gb->buffer+26)) {

142 av_log(log, AV_LOG_ERROR, "major sync info header checksum error\n");

143 return AVERROR_INVALIDDATA;

144 }

145

146 if (get_bits_long(gb, 24) != 0xf8726f) /* Sync words */

147 return AVERROR_INVALIDDATA;

148

149 mh->stream_type = get_bits(gb, 8);

150

151 if (mh->stream_type == 0xbb) {

152 mh->group1_bits = mlp_quants[get_bits(gb, 4)];

153 mh->group2_bits = mlp_quants[get_bits(gb, 4)];

154

155 ratebits = get_bits(gb, 4);

156 mh->group1_samplerate = mlp_samplerate(ratebits);

157 mh->group2_samplerate = mlp_samplerate(get_bits(gb, 4));

158

159 skip_bits(gb, 11);

160

161 mh->channel_arrangement=

162 channel_arrangement = get_bits(gb, 5);

163 mh->channels_mlp = mlp_channels[channel_arrangement];

164 mh->channel_layout_mlp = ff_mlp_layout[channel_arrangement];

165 } else if (mh->stream_type == 0xba) {

166 mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?

167 mh->group2_bits = 0;

168

169 ratebits = get_bits(gb, 4);

170 mh->group1_samplerate = mlp_samplerate(ratebits);

171 mh->group2_samplerate = 0;

172

173 skip_bits(gb, 4);

174

175 mh->channel_modifier_thd_stream0 = get_bits(gb, 2);

176 mh->channel_modifier_thd_stream1 = get_bits(gb, 2);

177

178 mh->channel_arrangement=

179 channel_arrangement = get_bits(gb, 5);

180 mh->channels_thd_stream1 = truehd_channels(channel_arrangement);

181 mh->channel_layout_thd_stream1 = ff_truehd_layout(channel_arrangement);

182

183 mh->channel_modifier_thd_stream2 = get_bits(gb, 2);

184

185 channel_arrangement = get_bits(gb, 13);

186 mh->channels_thd_stream2 = truehd_channels(channel_arrangement);

187 mh->channel_layout_thd_stream2 = ff_truehd_layout(channel_arrangement);

188 } else

189 return AVERROR_INVALIDDATA;

190

191 mh->access_unit_size = 40 << (ratebits & 7);

192 mh->access_unit_size_pow2 = 64 << (ratebits & 7);

193

194 skip_bits_long(gb, 48);

195

196 mh->is_vbr = get_bits1(gb);

197

198 mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;

199

200 mh->num_substreams = get_bits(gb, 4);

201

202 skip_bits_long(gb, 4 + 11 * 8);

203

204 return 0;

205 }

206

207 typedef struct MLPParseContext

208 {

209 ParseContext pc;

210

211 int bytes_left;

212

213 int in_sync;

214

215 int num_substreams;

216 } MLPParseContext;

217

218 static av_cold int mlp_init(AVCodecParserContext *s)

219 {

220 ff_mlp_init_crc();

221 return 0;

222 }

223

224 static int mlp_parse(AVCodecParserContext *s,

225 AVCodecContext *avctx,

226 const uint8_t **poutbuf, int *poutbuf_size,

227 const uint8_t *buf, int buf_size)

228 {

229 MLPParseContext *mp = s->priv_data;

230 int sync_present;

231 uint8_t parity_bits;

232 int next;

233 int ret;

234 int i, p = 0;

235

236 *poutbuf_size = 0;

237 if (buf_size == 0)

238 return 0;

239

240 if (!mp->in_sync) {

241 // Not in sync - find a major sync header

242

243 for (i = 0; i < buf_size; i++) {

244 mp->pc.state = (mp->pc.state << 8) | buf[i];

245 if ((mp->pc.state & 0xfffffffe) == 0xf8726fba &&

246 // ignore if we do not have the data for the start of header

247 mp->pc.index + i >= 7) {

248 mp->in_sync = 1;

249 mp->bytes_left = 0;

250 break;

251 }

252 }

253

254 if (!mp->in_sync) {

255 if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)

256 av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");

257 return buf_size;

258 }

259

260 if ((ret = ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size)) < 0) {

261 av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");

262 return ret;

263 }

264

265 return i - 7;

266 }

267

268 if (mp->bytes_left == 0) {

269 // Find length of this packet

270

271 /* Copy overread bytes from last frame into buffer. */

272 for(; mp->pc.overread>0; mp->pc.overread--) {

273 mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];

274 }

275

276 if (mp->pc.index + buf_size < 2) {

277 if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)

278 av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");

279 return buf_size;

280 }

281

282 mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)

283 | (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);

284 mp->bytes_left = (mp->bytes_left & 0xfff) * 2;

285 if (mp->bytes_left <= 0) { // prevent infinite loop

286 goto lost_sync;

287 }

288 mp->bytes_left -= mp->pc.index;

289 }

290

291 next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;

292

293 if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {

294 mp->bytes_left -= buf_size;

295 return buf_size;

296 }

297

298 mp->bytes_left = 0;

299

300 sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;

301

302 if (!sync_present) {

303 /* The first nibble of a frame is a parity check of the 4-byte

304 * access unit header and all the 2- or 4-byte substream headers. */

305 // Only check when this isn't a sync frame - syncs have a checksum.

306

307 parity_bits = 0;

308 for (i = -1; i < mp->num_substreams; i++) {

309 parity_bits ^= buf[p++];

310 parity_bits ^= buf[p++];

311

312 if (i < 0 || buf[p-2] & 0x80) {

313 parity_bits ^= buf[p++];

314 parity_bits ^= buf[p++];

315 }

316 }

317

318 if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {

319 av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");

320 goto lost_sync;

321 }

322 } else {

323 GetBitContext gb;

324 MLPHeaderInfo mh;

325

326 init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);

327 if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)

328 goto lost_sync;

329

330 avctx->bits_per_raw_sample = mh.group1_bits;

331 if (avctx->bits_per_raw_sample > 16)

332 avctx->sample_fmt = AV_SAMPLE_FMT_S32;

333 else

334 avctx->sample_fmt = AV_SAMPLE_FMT_S16;

335 avctx->sample_rate = mh.group1_samplerate;

336 s->duration = mh.access_unit_size;

337

338 if(!avctx->channels || !avctx->channel_layout) {

339 if (mh.stream_type == 0xbb) {

340 /* MLP stream */

341 #if FF_API_REQUEST_CHANNELS

342 FF_DISABLE_DEPRECATION_WARNINGS

343 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&

344 mh.num_substreams > 1) {

345 avctx->channels = 2;

346 avctx->channel_layout = AV_CH_LAYOUT_STEREO;

347 FF_ENABLE_DEPRECATION_WARNINGS

348 } else

349 #endif

350 if (avctx->request_channel_layout &&

351 (avctx->request_channel_layout & AV_CH_LAYOUT_STEREO) ==

352 avctx->request_channel_layout &&

353 mh.num_substreams > 1) {

354 avctx->channels = 2;

355 avctx->channel_layout = AV_CH_LAYOUT_STEREO;

356 } else {

357 avctx->channels = mh.channels_mlp;

358 avctx->channel_layout = mh.channel_layout_mlp;

359 }

360 } else { /* mh.stream_type == 0xba */

361 /* TrueHD stream */

362 #if FF_API_REQUEST_CHANNELS

363 FF_DISABLE_DEPRECATION_WARNINGS

364 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&

365 mh.num_substreams > 1) {

366 avctx->channels = 2;

367 avctx->channel_layout = AV_CH_LAYOUT_STEREO;

368 } else if (avctx->request_channels > 0 &&

369 avctx->request_channels <= mh.channels_thd_stream1) {

370 avctx->channels = mh.channels_thd_stream1;

371 avctx->channel_layout = mh.channel_layout_thd_stream1;

372 FF_ENABLE_DEPRECATION_WARNINGS

373 } else

374 #endif

375 if (avctx->request_channel_layout &&

376 (avctx->request_channel_layout & AV_CH_LAYOUT_STEREO) ==

377 avctx->request_channel_layout &&

378 mh.num_substreams > 1) {

379 avctx->channels = 2;

380 avctx->channel_layout = AV_CH_LAYOUT_STEREO;

381 } else if (!mh.channels_thd_stream2 ||

382 (avctx->request_channel_layout &&

383 (avctx->request_channel_layout & mh.channel_layout_thd_stream1) ==

384 avctx->request_channel_layout)) {

385 avctx->channels = mh.channels_thd_stream1;

386 avctx->channel_layout = mh.channel_layout_thd_stream1;

387 } else {

388 avctx->channels = mh.channels_thd_stream2;

389 avctx->channel_layout = mh.channel_layout_thd_stream2;

390 }

391 }

392 }

393

394 if (!mh.is_vbr) /* Stream is CBR */

395 avctx->bit_rate = mh.peak_bitrate;

396

397 mp->num_substreams = mh.num_substreams;

398 }

399

400 *poutbuf = buf;

401 *poutbuf_size = buf_size;

402

403 return next;

404

405 lost_sync:

406 mp->in_sync = 0;

407 return 1;

408 }

409

410 AVCodecParser ff_mlp_parser = {

411 .codec_ids = { AV_CODEC_ID_MLP, AV_CODEC_ID_TRUEHD },

412 .priv_data_size = sizeof(MLPParseContext),

413 .parser_init = mlp_init,

414 .parser_parse = mlp_parse,

415 .parser_close = ff_parse_close,

416 };

Generated on Sun Sep 14 2014 18:55:59 for FFmpeg by doxygen 1.8.2