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 "get_bits.h"

32 #include "parser.h"

33 #include "mlp_parser.h"

34 #include "mlp.h"

36 static const uint8_t mlp_quants[16] = {

37 16, 20, 24, 0, 0, 0, 0, 0,

38 0, 0, 0, 0, 0, 0, 0, 0,

39 };

41 static const uint8_t mlp_channels[32] = {

42 1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,

43 5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

44 };

46 const uint64_t ff_mlp_layout[32] = {

47 AV_CH_LAYOUT_MONO,

48 AV_CH_LAYOUT_STEREO,

49 AV_CH_LAYOUT_2_1,

50 AV_CH_LAYOUT_QUAD,

51 AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY,

52 AV_CH_LAYOUT_2_1|AV_CH_LOW_FREQUENCY,

53 AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,

54 AV_CH_LAYOUT_SURROUND,

55 AV_CH_LAYOUT_4POINT0,

56 AV_CH_LAYOUT_5POINT0_BACK,

57 AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,

58 AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,

59 AV_CH_LAYOUT_5POINT1_BACK,

60 AV_CH_LAYOUT_4POINT0,

61 AV_CH_LAYOUT_5POINT0_BACK,

62 AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,

63 AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,

64 AV_CH_LAYOUT_5POINT1_BACK,

65 AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,

66 AV_CH_LAYOUT_5POINT0_BACK,

67 AV_CH_LAYOUT_5POINT1_BACK,

68 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

69 };

71 static const uint8_t thd_chancount[13] = {

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

73 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 1

74 };

76 static const uint64_t thd_layout[13] = {

77 AV_CH_FRONT_LEFT|AV_CH_FRONT_RIGHT, // LR

78 AV_CH_FRONT_CENTER, // C

79 AV_CH_LOW_FREQUENCY, // LFE

80 AV_CH_SIDE_LEFT|AV_CH_SIDE_RIGHT, // LRs

81 AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT, // LRvh

82 AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER, // LRc

83 AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT, // LRrs

84 AV_CH_BACK_CENTER, // Cs

85 AV_CH_TOP_CENTER, // Ts

86 AV_CH_SURROUND_DIRECT_LEFT|AV_CH_SURROUND_DIRECT_RIGHT, // LRsd

87 AV_CH_WIDE_LEFT|AV_CH_WIDE_RIGHT, // LRw

88 AV_CH_TOP_FRONT_CENTER, // Cvh

89 AV_CH_LOW_FREQUENCY_2, // LFE2

90 };

92 static int mlp_samplerate(int in)

93 {

94 if (in == 0xF)

95 return 0;

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

98 }

100 static int truehd_channels(int chanmap)

101 {

102 int channels = 0, i;

103

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

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

106

107 return channels;

108 }

109

110 uint64_t ff_truehd_layout(int chanmap)

111 {

112 int i;

113 uint64_t layout = 0;

114

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

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

117

118 return layout;

119 }

120

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

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

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

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

125 */

126

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

128 {

129 int ratebits, channel_arrangement;

130 uint16_t checksum;

131

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

133

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

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

136 return -1;

137 }

138

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

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

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

142 return AVERROR_INVALIDDATA;

143 }

144

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

146 return AVERROR_INVALIDDATA;

147

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

149

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

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

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

153

154 ratebits = get_bits(gb, 4);

155 mh->group1_samplerate = mlp_samplerate(ratebits);

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

157

158 skip_bits(gb, 11);

159

160 mh->channel_arrangement=

161 channel_arrangement = get_bits(gb, 5);

162 mh->channels_mlp = mlp_channels[channel_arrangement];

163 mh->channel_layout_mlp = ff_mlp_layout[channel_arrangement];

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

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

166 mh->group2_bits = 0;

167

168 ratebits = get_bits(gb, 4);

169 mh->group1_samplerate = mlp_samplerate(ratebits);

170 mh->group2_samplerate = 0;

171

172 skip_bits(gb, 8);

173

174 mh->channel_arrangement=

175 channel_arrangement = get_bits(gb, 5);

176 mh->channels_thd_stream1 = truehd_channels(channel_arrangement);

177 mh->channel_layout_thd_stream1 = ff_truehd_layout(channel_arrangement);

178

179 skip_bits(gb, 2);

180

181 channel_arrangement = get_bits(gb, 13);

182 mh->channels_thd_stream2 = truehd_channels(channel_arrangement);

183 mh->channel_layout_thd_stream2 = ff_truehd_layout(channel_arrangement);

184 } else

185 return AVERROR_INVALIDDATA;

186

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

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

189

190 skip_bits_long(gb, 48);

191

192 mh->is_vbr = get_bits1(gb);

193

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

195

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

197

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

199

200 return 0;

201 }

202

203 typedef struct MLPParseContext

204 {

205 ParseContext pc;

206

207 int bytes_left;

208

209 int in_sync;

210

211 int num_substreams;

212 } MLPParseContext;

213

214 static av_cold int mlp_init(AVCodecParserContext *s)

215 {

216 ff_mlp_init_crc();

217 return 0;

218 }

219

220 static int mlp_parse(AVCodecParserContext *s,

221 AVCodecContext *avctx,

222 const uint8_t **poutbuf, int *poutbuf_size,

223 const uint8_t *buf, int buf_size)

224 {

225 MLPParseContext *mp = s->priv_data;

226 int sync_present;

227 uint8_t parity_bits;

228 int next;

229 int i, p = 0;

230

231 *poutbuf_size = 0;

232 if (buf_size == 0)

233 return 0;

234

235 if (!mp->in_sync) {

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

237

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

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

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

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

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

243 mp->in_sync = 1;

244 mp->bytes_left = 0;

245 break;

246 }

247 }

248

249 if (!mp->in_sync) {

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

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

252 return buf_size;

253 }

254

255 ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);

256

257 return i - 7;

258 }

259

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

261 // Find length of this packet

262

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

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

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

266 }

267

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

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

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

271 return buf_size;

272 }

273

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

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

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

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

278 goto lost_sync;

279 }

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

281 }

282

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

284

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

286 mp->bytes_left -= buf_size;

287 return buf_size;

288 }

289

290 mp->bytes_left = 0;

291

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

293

294 if (!sync_present) {

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

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

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

298

299 parity_bits = 0;

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

301 parity_bits ^= buf[p++];

302 parity_bits ^= buf[p++];

303

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

305 parity_bits ^= buf[p++];

306 parity_bits ^= buf[p++];

307 }

308 }

309

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

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

312 goto lost_sync;

313 }

314 } else {

315 GetBitContext gb;

316 MLPHeaderInfo mh;

317

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

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

320 goto lost_sync;

321

322 avctx->bits_per_raw_sample = mh.group1_bits;

323 if (avctx->bits_per_raw_sample > 16)

324 avctx->sample_fmt = AV_SAMPLE_FMT_S32;

325 else

326 avctx->sample_fmt = AV_SAMPLE_FMT_S16;

327 avctx->sample_rate = mh.group1_samplerate;

328 s->duration = mh.access_unit_size;

329

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

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

332 /* MLP stream */

333 #if FF_API_REQUEST_CHANNELS

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

335 mh.num_substreams > 1) {

336 avctx->channels = 2;

337 avctx->channel_layout = AV_CH_LAYOUT_STEREO;

338 } else

339 #endif

340 if (avctx->request_channel_layout == AV_CH_LAYOUT_STEREO &&

341 mh.num_substreams > 1) {

342 avctx->channels = 2;

343 avctx->channel_layout = AV_CH_LAYOUT_STEREO;

344 } else {

345 avctx->channels = mh.channels_mlp;

346 avctx->channel_layout = mh.channel_layout_mlp;

347 }

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

349 /* TrueHD stream */

350 #if FF_API_REQUEST_CHANNELS

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

352 mh.num_substreams > 1) {

353 avctx->channels = 2;

354 avctx->channel_layout = AV_CH_LAYOUT_STEREO;

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

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

357 avctx->channels = mh.channels_thd_stream1;

358 avctx->channel_layout = mh.channel_layout_thd_stream1;

359 } else

360 #endif

361 if (avctx->request_channel_layout == AV_CH_LAYOUT_STEREO &&

362 mh.num_substreams > 1) {

363 avctx->channels = 2;

364 avctx->channel_layout = AV_CH_LAYOUT_STEREO;

365 } else if (avctx->request_channel_layout == mh.channel_layout_thd_stream1 ||

366 !mh.channels_thd_stream2) {

367 avctx->channels = mh.channels_thd_stream1;

368 avctx->channel_layout = mh.channel_layout_thd_stream1;

369 } else {

370 avctx->channels = mh.channels_thd_stream2;

371 avctx->channel_layout = mh.channel_layout_thd_stream2;

372 }

373 }

374 }

375

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

377 avctx->bit_rate = mh.peak_bitrate;

378

379 mp->num_substreams = mh.num_substreams;

380 }

381

382 *poutbuf = buf;

383 *poutbuf_size = buf_size;

384

385 return next;

386

387 lost_sync:

388 mp->in_sync = 0;

389 return 1;

390 }

391

392 AVCodecParser ff_mlp_parser = {

393 .codec_ids = { AV_CODEC_ID_MLP, AV_CODEC_ID_TRUEHD },

394 .priv_data_size = sizeof(MLPParseContext),

395 .parser_init = mlp_init,

396 .parser_parse = mlp_parse,

397 .parser_close = ff_parse_close,

398 };

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