3 * Copyright (c) 2007 Ian Caulfield
5 * This file is part of FFmpeg.
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.
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.
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
27 #include "libavutil/crc.h"
28 #include "bitstream.h"
30 #include "mlp_parser.h"
32 static const uint8_t mlp_quants[16] = {
33 16, 20, 24, 0, 0, 0, 0, 0,
34 0, 0, 0, 0, 0, 0, 0, 0,
37 static const uint8_t mlp_channels[32] = {
38 1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,
39 5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
42 static const uint8_t thd_chancount[13] = {
43 // LR C LFE LRs LRvh LRc LRrs Cs Ts LRsd LRw Cvh LFE2
44 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 1
47 static int mlp_samplerate(int in)
52 return (in & 8 ? 44100 : 48000) << (in & 7) ;
55 static int truehd_channels(int chanmap)
59 for (i = 0; i < 13; i++)
60 channels += thd_chancount[i] * ((chanmap >> i) & 1);
65 static int crc_init = 0;
66 static AVCRC crc_2D[1024];
68 /** MLP uses checksums that seem to be based on the standard CRC algorithm,
69 * but not (in implementation terms, the table lookup and XOR are reversed).
70 * We can implement this behavior using a standard av_crc on all but the
71 * last element, then XOR that with the last element.
74 static uint16_t mlp_checksum16(const uint8_t *buf, unsigned int buf_size)
79 av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D));
83 crc = av_crc(crc_2D, 0, buf, buf_size - 2);
84 crc ^= AV_RL16(buf + buf_size - 2);
88 /** Read a major sync info header - contains high level information about
89 * the stream - sample rate, channel arrangement etc. Most of this
90 * information is not actually necessary for decoding, only for playback.
91 * gb must be a freshly initialized GetBitContext with no bits read.
94 int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, GetBitContext *gb)
99 assert(get_bits_count(gb) == 0);
101 if (gb->size_in_bits < 28 << 3) {
102 av_log(log, AV_LOG_ERROR, "Packet too short, unable to read major sync\n");
106 checksum = mlp_checksum16(gb->buffer, 26);
107 if (checksum != AV_RL16(gb->buffer+26)) {
108 av_log(log, AV_LOG_ERROR, "Major sync info header checksum error\n");
112 if (get_bits_long(gb, 24) != 0xf8726f) /* Sync words */
115 mh->stream_type = get_bits(gb, 8);
117 if (mh->stream_type == 0xbb) {
118 mh->group1_bits = mlp_quants[get_bits(gb, 4)];
119 mh->group2_bits = mlp_quants[get_bits(gb, 4)];
121 ratebits = get_bits(gb, 4);
122 mh->group1_samplerate = mlp_samplerate(ratebits);
123 mh->group2_samplerate = mlp_samplerate(get_bits(gb, 4));
127 mh->channels_mlp = get_bits(gb, 5);
128 } else if (mh->stream_type == 0xba) {
129 mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
132 ratebits = get_bits(gb, 4);
133 mh->group1_samplerate = mlp_samplerate(ratebits);
134 mh->group2_samplerate = 0;
138 mh->channels_thd_stream1 = get_bits(gb, 5);
142 mh->channels_thd_stream2 = get_bits(gb, 13);
146 mh->access_unit_size = 40 << (ratebits & 7);
147 mh->access_unit_size_pow2 = 64 << (ratebits & 7);
149 skip_bits_long(gb, 48);
151 mh->is_vbr = get_bits1(gb);
153 mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;
155 mh->num_substreams = get_bits(gb, 4);
157 skip_bits_long(gb, 4 + 11 * 8);
162 typedef struct MLPParseContext
173 static int mlp_parse(AVCodecParserContext *s,
174 AVCodecContext *avctx,
175 const uint8_t **poutbuf, int *poutbuf_size,
176 const uint8_t *buf, int buf_size)
178 MLPParseContext *mp = s->priv_data;
189 // Not in sync - find a major sync header
191 for (i = 0; i < buf_size; i++) {
192 mp->pc.state = (mp->pc.state << 8) | buf[i];
193 if ((mp->pc.state & 0xfffffffe) == 0xf8726fba) {
201 ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
205 ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);
210 if (mp->bytes_left == 0) {
211 // Find length of this packet
213 /* Copy overread bytes from last frame into buffer. */
214 for(; mp->pc.overread>0; mp->pc.overread--) {
215 mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
218 if (mp->pc.index + buf_size < 2) {
219 ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
223 mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
224 | (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
225 mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
226 mp->bytes_left -= mp->pc.index;
229 next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;
231 if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
232 mp->bytes_left -= buf_size;
238 sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;
241 // First nibble of a frame is a parity check of the first few nibbles.
242 // Only check when this isn't a sync frame - syncs have a checksum.
245 for (i = -1; i < mp->num_substreams; i++) {
246 parity_bits ^= buf[p++];
247 parity_bits ^= buf[p++];
249 if (i < 0 || buf[p-2] & 0x80) {
250 parity_bits ^= buf[p++];
251 parity_bits ^= buf[p++];
255 if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
256 av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
263 init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
264 if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
267 #ifdef CONFIG_AUDIO_NONSHORT
268 avctx->bits_per_sample = mh.group1_bits;
269 if (avctx->bits_per_sample > 16)
270 avctx->sample_fmt = SAMPLE_FMT_S32;
272 avctx->sample_rate = mh.group1_samplerate;
273 avctx->frame_size = mh.access_unit_size;
275 if (mh.stream_type == 0xbb) {
277 avctx->channels = mlp_channels[mh.channels_mlp];
278 } else { /* mh.stream_type == 0xba */
280 if (mh.channels_thd_stream2)
281 avctx->channels = truehd_channels(mh.channels_thd_stream2);
283 avctx->channels = truehd_channels(mh.channels_thd_stream1);
286 if (!mh.is_vbr) /* Stream is CBR */
287 avctx->bit_rate = mh.peak_bitrate;
289 mp->num_substreams = mh.num_substreams;
293 *poutbuf_size = buf_size;
302 AVCodecParser mlp_parser = {
304 sizeof(MLPParseContext),