Libav
mlp_parser.c
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1 /*
2  * MLP parser
3  * Copyright (c) 2007 Ian Caulfield
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
27 #include <stdint.h>
28 
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"
36 
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 };
41 
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 };
46 
47 static const uint64_t mlp_layout[32] = {
52  AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY,
53  AV_CH_LAYOUT_2_1|AV_CH_LOW_FREQUENCY,
54  AV_CH_LAYOUT_2_2|AV_CH_LOW_FREQUENCY,
58  AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
59  AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
63  AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
64  AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
66  AV_CH_LAYOUT_2_2|AV_CH_LOW_FREQUENCY,
69  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
70 };
71 
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 };
76 
77 static const uint64_t thd_layout[13] = {
79  AV_CH_FRONT_CENTER, // C
80  AV_CH_LOW_FREQUENCY, // LFE
85  AV_CH_BACK_CENTER, // Cs
86  AV_CH_TOP_CENTER, // Ts
90  AV_CH_LOW_FREQUENCY_2, // LFE2
91 };
92 
93 static int mlp_samplerate(int in)
94 {
95  if (in == 0xF)
96  return 0;
97 
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 static uint64_t 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 
129 {
130  int ratebits, channel_arrangement;
131  uint16_t checksum;
132 
133  assert(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);
158 
159  skip_bits(gb, 11);
160 
161  channel_arrangement = get_bits(gb, 5);
162  mh->channels_mlp = mlp_channels[channel_arrangement];
163  mh->channel_layout_mlp = 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, 4);
173 
176 
177  channel_arrangement = get_bits(gb, 5);
178  mh->channels_thd_stream1 = truehd_channels(channel_arrangement);
179  mh->channel_layout_thd_stream1 = truehd_layout(channel_arrangement);
180 
182 
183  channel_arrangement = get_bits(gb, 13);
184  mh->channels_thd_stream2 = truehd_channels(channel_arrangement);
185  mh->channel_layout_thd_stream2 = truehd_layout(channel_arrangement);
186  } else
187  return AVERROR_INVALIDDATA;
188 
189  mh->access_unit_size = 40 << (ratebits & 7);
190  mh->access_unit_size_pow2 = 64 << (ratebits & 7);
191 
192  skip_bits_long(gb, 48);
193 
194  mh->is_vbr = get_bits1(gb);
195 
196  mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;
197 
198  mh->num_substreams = get_bits(gb, 4);
199 
200  skip_bits_long(gb, 4 + 11 * 8);
201 
202  return 0;
203 }
204 
205 typedef struct MLPParseContext
206 {
208 
210 
211  int in_sync;
212 
215 
217 {
218  ff_mlp_init_crc();
219  return 0;
220 }
221 
223  AVCodecContext *avctx,
224  const uint8_t **poutbuf, int *poutbuf_size,
225  const uint8_t *buf, int buf_size)
226 {
227  MLPParseContext *mp = s->priv_data;
228  int sync_present;
229  uint8_t parity_bits;
230  int next;
231  int i, p = 0;
232 
233  *poutbuf_size = 0;
234  if (buf_size == 0)
235  return 0;
236 
237  if (!mp->in_sync) {
238  // Not in sync - find a major sync header
239 
240  for (i = 0; i < buf_size; i++) {
241  mp->pc.state = (mp->pc.state << 8) | buf[i];
242  if ((mp->pc.state & 0xfffffffe) == 0xf8726fba &&
243  // ignore if we do not have the data for the start of header
244  mp->pc.index + i >= 7) {
245  mp->in_sync = 1;
246  mp->bytes_left = 0;
247  break;
248  }
249  }
250 
251  if (!mp->in_sync) {
252  ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
253  return buf_size;
254  }
255 
256  ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);
257 
258  return i - 7;
259  }
260 
261  if (mp->bytes_left == 0) {
262  // Find length of this packet
263 
264  /* Copy overread bytes from last frame into buffer. */
265  for(; mp->pc.overread>0; mp->pc.overread--) {
266  mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
267  }
268 
269  if (mp->pc.index + buf_size < 2) {
270  ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
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  mp->bytes_left -= mp->pc.index;
278  }
279 
280  next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;
281 
282  if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
283  mp->bytes_left -= buf_size;
284  return buf_size;
285  }
286 
287  mp->bytes_left = 0;
288 
289  sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;
290 
291  if (!sync_present) {
292  /* The first nibble of a frame is a parity check of the 4-byte
293  * access unit header and all the 2- or 4-byte substream headers. */
294  // Only check when this isn't a sync frame - syncs have a checksum.
295 
296  parity_bits = 0;
297  for (i = -1; i < mp->num_substreams; i++) {
298  parity_bits ^= buf[p++];
299  parity_bits ^= buf[p++];
300 
301  if (i < 0 || buf[p-2] & 0x80) {
302  parity_bits ^= buf[p++];
303  parity_bits ^= buf[p++];
304  }
305  }
306 
307  if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
308  av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
309  goto lost_sync;
310  }
311  } else {
312  GetBitContext gb;
313  MLPHeaderInfo mh;
314 
315  init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
316  if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
317  goto lost_sync;
318 
319  avctx->bits_per_raw_sample = mh.group1_bits;
320  if (avctx->bits_per_raw_sample > 16)
321  avctx->sample_fmt = AV_SAMPLE_FMT_S32;
322  else
323  avctx->sample_fmt = AV_SAMPLE_FMT_S16;
324  avctx->sample_rate = mh.group1_samplerate;
325  s->duration = mh.access_unit_size;
326 
327  if (mh.stream_type == 0xbb) {
328  /* MLP stream */
329 #if FF_API_REQUEST_CHANNELS
331  if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
332  mh.num_substreams > 1) {
333  avctx->channels = 2;
335  } else
337 #endif
338  if (avctx->request_channel_layout &&
340  avctx->request_channel_layout &&
341  mh.num_substreams > 1) {
342  avctx->channels = 2;
344  } else {
345  avctx->channels = mh.channels_mlp;
347  }
348  } else { /* mh.stream_type == 0xba */
349  /* TrueHD stream */
350 #if FF_API_REQUEST_CHANNELS
352  if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
353  mh.num_substreams > 1) {
354  avctx->channels = 2;
356  } else if (avctx->request_channels > 0 &&
357  avctx->request_channels <= mh.channels_thd_stream1) {
358  avctx->channels = mh.channels_thd_stream1;
360  } else
362 #endif
363  if (avctx->request_channel_layout &&
365  avctx->request_channel_layout &&
366  mh.num_substreams > 1) {
367  avctx->channels = 2;
369  } else if (!mh.channels_thd_stream2 ||
370  (avctx->request_channel_layout &&
372  avctx->request_channel_layout)) {
373  avctx->channels = mh.channels_thd_stream1;
375  } else {
376  avctx->channels = mh.channels_thd_stream2;
378  }
379  }
380 
381  if (!mh.is_vbr) /* Stream is CBR */
382  avctx->bit_rate = mh.peak_bitrate;
383 
385  }
386 
387  *poutbuf = buf;
388  *poutbuf_size = buf_size;
389 
390  return next;
391 
392 lost_sync:
393  mp->in_sync = 0;
394  return 1;
395 }
396 
399  .priv_data_size = sizeof(MLPParseContext),
400  .parser_init = mlp_init,
401  .parser_parse = mlp_parse,
402  .parser_close = ff_parse_close,
403 };