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
29 #include "libavutil/crc.h"
30 #include "bitstream.h"
32 #include "mlp_parser.h"
34 static const uint8_t mlp_quants[16] = {
35 16, 20, 24, 0, 0, 0, 0, 0,
36 0, 0, 0, 0, 0, 0, 0, 0,
39 static const uint8_t mlp_channels[32] = {
40 1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,
41 5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
44 static const uint8_t thd_chancount[13] = {
45 // LR C LFE LRs LRvh LRc LRrs Cs Ts LRsd LRw Cvh LFE2
46 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 1
49 static int mlp_samplerate(int in)
54 return (in & 8 ? 44100 : 48000) << (in & 7) ;
57 static int truehd_channels(int chanmap)
61 for (i = 0; i < 13; i++)
62 channels += thd_chancount[i] * ((chanmap >> i) & 1);
67 static int crc_init = 0;
68 static AVCRC crc_2D[1024];
70 /** MLP uses checksums that seem to be based on the standard CRC algorithm, but
71 * are not (in implementation terms, the table lookup and XOR are reversed).
72 * We can implement this behavior using a standard av_crc on all but the
73 * last element, then XOR that with the last element.
76 static uint16_t mlp_checksum16(const uint8_t *buf, unsigned int buf_size)
81 av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D));
85 crc = av_crc(crc_2D, 0, buf, buf_size - 2);
86 crc ^= AV_RL16(buf + buf_size - 2);
90 /** Read a major sync info header - contains high level information about
91 * the stream - sample rate, channel arrangement etc. Most of this
92 * information is not actually necessary for decoding, only for playback.
93 * gb must be a freshly initialized GetBitContext with no bits read.
96 int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, GetBitContext *gb)
101 assert(get_bits_count(gb) == 0);
103 if (gb->size_in_bits < 28 << 3) {
104 av_log(log, AV_LOG_ERROR, "packet too short, unable to read major sync\n");
108 checksum = mlp_checksum16(gb->buffer, 26);
109 if (checksum != AV_RL16(gb->buffer+26)) {
110 av_log(log, AV_LOG_ERROR, "major sync info header checksum error\n");
114 if (get_bits_long(gb, 24) != 0xf8726f) /* Sync words */
117 mh->stream_type = get_bits(gb, 8);
119 if (mh->stream_type == 0xbb) {
120 mh->group1_bits = mlp_quants[get_bits(gb, 4)];
121 mh->group2_bits = mlp_quants[get_bits(gb, 4)];
123 ratebits = get_bits(gb, 4);
124 mh->group1_samplerate = mlp_samplerate(ratebits);
125 mh->group2_samplerate = mlp_samplerate(get_bits(gb, 4));
129 mh->channels_mlp = get_bits(gb, 5);
130 } else if (mh->stream_type == 0xba) {
131 mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
134 ratebits = get_bits(gb, 4);
135 mh->group1_samplerate = mlp_samplerate(ratebits);
136 mh->group2_samplerate = 0;
140 mh->channels_thd_stream1 = get_bits(gb, 5);
144 mh->channels_thd_stream2 = get_bits(gb, 13);
148 mh->access_unit_size = 40 << (ratebits & 7);
149 mh->access_unit_size_pow2 = 64 << (ratebits & 7);
151 skip_bits_long(gb, 48);
153 mh->is_vbr = get_bits1(gb);
155 mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;
157 mh->num_substreams = get_bits(gb, 4);
159 skip_bits_long(gb, 4 + 11 * 8);
164 typedef struct MLPParseContext
175 static int mlp_parse(AVCodecParserContext *s,
176 AVCodecContext *avctx,
177 const uint8_t **poutbuf, int *poutbuf_size,
178 const uint8_t *buf, int buf_size)
180 MLPParseContext *mp = s->priv_data;
191 // Not in sync - find a major sync header
193 for (i = 0; i < buf_size; i++) {
194 mp->pc.state = (mp->pc.state << 8) | buf[i];
195 if ((mp->pc.state & 0xfffffffe) == 0xf8726fba) {
203 ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
207 ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);
212 if (mp->bytes_left == 0) {
213 // Find length of this packet
215 /* Copy overread bytes from last frame into buffer. */
216 for(; mp->pc.overread>0; mp->pc.overread--) {
217 mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
220 if (mp->pc.index + buf_size < 2) {
221 ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
225 mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
226 | (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
227 mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
228 mp->bytes_left -= mp->pc.index;
231 next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;
233 if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
234 mp->bytes_left -= buf_size;
240 sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;
243 /* The first nibble of a frame is a parity check of the 4-byte
244 * access unit header and all the 2- or 4-byte substream headers. */
245 // Only check when this isn't a sync frame - syncs have a checksum.
248 for (i = -1; i < mp->num_substreams; i++) {
249 parity_bits ^= buf[p++];
250 parity_bits ^= buf[p++];
252 if (i < 0 || buf[p-2] & 0x80) {
253 parity_bits ^= buf[p++];
254 parity_bits ^= buf[p++];
258 if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
259 av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
266 init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
267 if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
270 #ifdef CONFIG_AUDIO_NONSHORT
271 avctx->bits_per_sample = mh.group1_bits;
272 if (avctx->bits_per_sample > 16)
273 avctx->sample_fmt = SAMPLE_FMT_S32;
275 avctx->sample_rate = mh.group1_samplerate;
276 avctx->frame_size = mh.access_unit_size;
278 if (mh.stream_type == 0xbb) {
280 avctx->channels = mlp_channels[mh.channels_mlp];
281 } else { /* mh.stream_type == 0xba */
283 if (mh.channels_thd_stream2)
284 avctx->channels = truehd_channels(mh.channels_thd_stream2);
286 avctx->channels = truehd_channels(mh.channels_thd_stream1);
289 if (!mh.is_vbr) /* Stream is CBR */
290 avctx->bit_rate = mh.peak_bitrate;
292 mp->num_substreams = mh.num_substreams;
296 *poutbuf_size = buf_size;
305 AVCodecParser mlp_parser = {
307 sizeof(MLPParseContext),