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 "get_bits.h"
32 #include "parser.h"
33 #include "mlp_parser.h"
34 #include "mlp.h"
35 
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 };
40 
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 };
45 
46 static const uint64_t mlp_layout[32] = {
51  AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY,
52  AV_CH_LAYOUT_2_1|AV_CH_LOW_FREQUENCY,
53  AV_CH_LAYOUT_2_2|AV_CH_LOW_FREQUENCY,
57  AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
58  AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
62  AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
63  AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
65  AV_CH_LAYOUT_2_2|AV_CH_LOW_FREQUENCY,
68  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
69 };
70 
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 };
75 
76 static const uint64_t thd_layout[13] = {
78  AV_CH_FRONT_CENTER, // C
79  AV_CH_LOW_FREQUENCY, // LFE
84  AV_CH_BACK_CENTER, // Cs
85  AV_CH_TOP_CENTER, // Ts
89  AV_CH_LOW_FREQUENCY_2, // LFE2
90 };
91 
92 static int mlp_samplerate(int in)
93 {
94  if (in == 0xF)
95  return 0;
96 
97  return (in & 8 ? 44100 : 48000) << (in & 7) ;
98 }
99 
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 static uint64_t 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 
128 {
129  int ratebits, channel_arrangement;
130  uint16_t checksum;
131 
132  assert(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);
157 
158  skip_bits(gb, 11);
159 
160  channel_arrangement = get_bits(gb, 5);
161  mh->channels_mlp = mlp_channels[channel_arrangement];
162  mh->channel_layout_mlp = mlp_layout[channel_arrangement];
163  } else if (mh->stream_type == 0xba) {
164  mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
165  mh->group2_bits = 0;
166 
167  ratebits = get_bits(gb, 4);
168  mh->group1_samplerate = mlp_samplerate(ratebits);
169  mh->group2_samplerate = 0;
170 
171  skip_bits(gb, 8);
172 
173  channel_arrangement = get_bits(gb, 5);
174  mh->channels_thd_stream1 = truehd_channels(channel_arrangement);
175  mh->channel_layout_thd_stream1 = truehd_layout(channel_arrangement);
176 
177  skip_bits(gb, 2);
178 
179  channel_arrangement = get_bits(gb, 13);
180  mh->channels_thd_stream2 = truehd_channels(channel_arrangement);
181  mh->channel_layout_thd_stream2 = truehd_layout(channel_arrangement);
182  } else
183  return AVERROR_INVALIDDATA;
184 
185  mh->access_unit_size = 40 << (ratebits & 7);
186  mh->access_unit_size_pow2 = 64 << (ratebits & 7);
187 
188  skip_bits_long(gb, 48);
189 
190  mh->is_vbr = get_bits1(gb);
191 
192  mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;
193 
194  mh->num_substreams = get_bits(gb, 4);
195 
196  skip_bits_long(gb, 4 + 11 * 8);
197 
198  return 0;
199 }
200 
201 typedef struct MLPParseContext
202 {
204 
206 
207  int in_sync;
208 
211 
213 {
214  ff_mlp_init_crc();
215  return 0;
216 }
217 
219  AVCodecContext *avctx,
220  const uint8_t **poutbuf, int *poutbuf_size,
221  const uint8_t *buf, int buf_size)
222 {
223  MLPParseContext *mp = s->priv_data;
224  int sync_present;
225  uint8_t parity_bits;
226  int next;
227  int i, p = 0;
228 
229  *poutbuf_size = 0;
230  if (buf_size == 0)
231  return 0;
232 
233  if (!mp->in_sync) {
234  // Not in sync - find a major sync header
235 
236  for (i = 0; i < buf_size; i++) {
237  mp->pc.state = (mp->pc.state << 8) | buf[i];
238  if ((mp->pc.state & 0xfffffffe) == 0xf8726fba &&
239  // ignore if we do not have the data for the start of header
240  mp->pc.index + i >= 7) {
241  mp->in_sync = 1;
242  mp->bytes_left = 0;
243  break;
244  }
245  }
246 
247  if (!mp->in_sync) {
248  ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
249  return buf_size;
250  }
251 
252  ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);
253 
254  return i - 7;
255  }
256 
257  if (mp->bytes_left == 0) {
258  // Find length of this packet
259 
260  /* Copy overread bytes from last frame into buffer. */
261  for(; mp->pc.overread>0; mp->pc.overread--) {
262  mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
263  }
264 
265  if (mp->pc.index + buf_size < 2) {
266  ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
267  return buf_size;
268  }
269 
270  mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
271  | (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
272  mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
273  mp->bytes_left -= mp->pc.index;
274  }
275 
276  next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;
277 
278  if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
279  mp->bytes_left -= buf_size;
280  return buf_size;
281  }
282 
283  mp->bytes_left = 0;
284 
285  sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;
286 
287  if (!sync_present) {
288  /* The first nibble of a frame is a parity check of the 4-byte
289  * access unit header and all the 2- or 4-byte substream headers. */
290  // Only check when this isn't a sync frame - syncs have a checksum.
291 
292  parity_bits = 0;
293  for (i = -1; i < mp->num_substreams; i++) {
294  parity_bits ^= buf[p++];
295  parity_bits ^= buf[p++];
296 
297  if (i < 0 || buf[p-2] & 0x80) {
298  parity_bits ^= buf[p++];
299  parity_bits ^= buf[p++];
300  }
301  }
302 
303  if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
304  av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
305  goto lost_sync;
306  }
307  } else {
308  GetBitContext gb;
309  MLPHeaderInfo mh;
310 
311  init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
312  if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
313  goto lost_sync;
314 
315  avctx->bits_per_raw_sample = mh.group1_bits;
316  if (avctx->bits_per_raw_sample > 16)
317  avctx->sample_fmt = AV_SAMPLE_FMT_S32;
318  else
319  avctx->sample_fmt = AV_SAMPLE_FMT_S16;
320  avctx->sample_rate = mh.group1_samplerate;
321  s->duration = mh.access_unit_size;
322 
323  if (mh.stream_type == 0xbb) {
324  /* MLP stream */
325  avctx->channels = mh.channels_mlp;
327  } else { /* mh.stream_type == 0xba */
328  /* TrueHD stream */
329  if (mh.channels_thd_stream2) {
330  avctx->channels = mh.channels_thd_stream2;
332  } else {
333  avctx->channels = mh.channels_thd_stream1;
335  }
336  }
337 
338  if (!mh.is_vbr) /* Stream is CBR */
339  avctx->bit_rate = mh.peak_bitrate;
340 
342  }
343 
344  *poutbuf = buf;
345  *poutbuf_size = buf_size;
346 
347  return next;
348 
349 lost_sync:
350  mp->in_sync = 0;
351  return 1;
352 }
353 
356  .priv_data_size = sizeof(MLPParseContext),
357  .parser_init = mlp_init,
358  .parser_parse = mlp_parse,
359  .parser_close = ff_parse_close,
360 };