mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-11-21 10:55:51 +02:00
308 lines
8.3 KiB
C
308 lines
8.3 KiB
C
/*
|
|
* MLP parser
|
|
* Copyright (c) 2007 Ian Caulfield
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
/**
|
|
* @file mlp_parser.c
|
|
* MLP parser
|
|
*/
|
|
|
|
#include "libavutil/crc.h"
|
|
#include "bitstream.h"
|
|
#include "parser.h"
|
|
#include "mlp_parser.h"
|
|
|
|
static const uint8_t mlp_quants[16] = {
|
|
16, 20, 24, 0, 0, 0, 0, 0,
|
|
0, 0, 0, 0, 0, 0, 0, 0,
|
|
};
|
|
|
|
static const uint8_t mlp_channels[32] = {
|
|
1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,
|
|
5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
|
|
};
|
|
|
|
static const uint8_t thd_chancount[13] = {
|
|
// LR C LFE LRs LRvh LRc LRrs Cs Ts LRsd LRw Cvh LFE2
|
|
2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 1
|
|
};
|
|
|
|
static int mlp_samplerate(int in)
|
|
{
|
|
if (in == 0xF)
|
|
return 0;
|
|
|
|
return (in & 8 ? 44100 : 48000) << (in & 7) ;
|
|
}
|
|
|
|
static int truehd_channels(int chanmap)
|
|
{
|
|
int channels = 0, i;
|
|
|
|
for (i = 0; i < 13; i++)
|
|
channels += thd_chancount[i] * ((chanmap >> i) & 1);
|
|
|
|
return channels;
|
|
}
|
|
|
|
static int crc_init = 0;
|
|
static AVCRC crc_2D[1024];
|
|
|
|
/** MLP uses checksums that seem to be based on the standard CRC algorithm,
|
|
* but not (in implementation terms, the table lookup and XOR are reversed).
|
|
* We can implement this behavior using a standard av_crc on all but the
|
|
* last element, then XOR that with the last element.
|
|
*/
|
|
|
|
static uint16_t mlp_checksum16(const uint8_t *buf, unsigned int buf_size)
|
|
{
|
|
uint16_t crc;
|
|
|
|
if (!crc_init) {
|
|
av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D));
|
|
crc_init = 1;
|
|
}
|
|
|
|
crc = av_crc(crc_2D, 0, buf, buf_size - 2);
|
|
crc ^= AV_RL16(buf + buf_size - 2);
|
|
return crc;
|
|
}
|
|
|
|
/** Read a major sync info header - contains high level information about
|
|
* the stream - sample rate, channel arrangement etc. Most of this
|
|
* information is not actually necessary for decoding, only for playback.
|
|
*/
|
|
|
|
int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, const uint8_t *buf,
|
|
unsigned int buf_size)
|
|
{
|
|
GetBitContext gb;
|
|
int ratebits;
|
|
uint16_t checksum;
|
|
|
|
if (buf_size < 28) {
|
|
av_log(log, AV_LOG_ERROR, "Packet too short, unable to read major sync\n");
|
|
return -1;
|
|
}
|
|
|
|
checksum = mlp_checksum16(buf, 26);
|
|
if (checksum != AV_RL16(buf+26)) {
|
|
av_log(log, AV_LOG_ERROR, "Major sync info header checksum error\n");
|
|
return -1;
|
|
}
|
|
|
|
init_get_bits(&gb, buf, buf_size * 8);
|
|
|
|
if (get_bits_long(&gb, 24) != 0xf8726f) /* Sync words */
|
|
return -1;
|
|
|
|
mh->stream_type = get_bits(&gb, 8);
|
|
|
|
if (mh->stream_type == 0xbb) {
|
|
mh->group1_bits = mlp_quants[get_bits(&gb, 4)];
|
|
mh->group2_bits = mlp_quants[get_bits(&gb, 4)];
|
|
|
|
ratebits = get_bits(&gb, 4);
|
|
mh->group1_samplerate = mlp_samplerate(ratebits);
|
|
mh->group2_samplerate = mlp_samplerate(get_bits(&gb, 4));
|
|
|
|
skip_bits(&gb, 11);
|
|
|
|
mh->channels_mlp = get_bits(&gb, 5);
|
|
} else if (mh->stream_type == 0xba) {
|
|
mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
|
|
mh->group2_bits = 0;
|
|
|
|
ratebits = get_bits(&gb, 4);
|
|
mh->group1_samplerate = mlp_samplerate(ratebits);
|
|
mh->group2_samplerate = 0;
|
|
|
|
skip_bits(&gb, 8);
|
|
|
|
mh->channels_thd_stream1 = get_bits(&gb, 5);
|
|
|
|
skip_bits(&gb, 2);
|
|
|
|
mh->channels_thd_stream2 = get_bits(&gb, 13);
|
|
} else
|
|
return -1;
|
|
|
|
mh->access_unit_size = 40 << (ratebits & 7);
|
|
mh->access_unit_size_pow2 = 64 << (ratebits & 7);
|
|
|
|
skip_bits_long(&gb, 48);
|
|
|
|
mh->is_vbr = get_bits1(&gb);
|
|
|
|
mh->peak_bitrate = (get_bits(&gb, 15) * mh->group1_samplerate + 8) >> 4;
|
|
|
|
mh->num_substreams = get_bits(&gb, 4);
|
|
|
|
skip_bits_long(&gb, 4 + 11 * 8);
|
|
|
|
return 0;
|
|
}
|
|
|
|
typedef struct MLPParseContext
|
|
{
|
|
ParseContext pc;
|
|
|
|
int bytes_left;
|
|
|
|
int in_sync;
|
|
|
|
int num_substreams;
|
|
} MLPParseContext;
|
|
|
|
static int mlp_parse(AVCodecParserContext *s,
|
|
AVCodecContext *avctx,
|
|
const uint8_t **poutbuf, int *poutbuf_size,
|
|
const uint8_t *buf, int buf_size)
|
|
{
|
|
MLPParseContext *mp = s->priv_data;
|
|
int sync_present;
|
|
uint8_t parity_bits;
|
|
int next;
|
|
int i, p = 0;
|
|
|
|
*poutbuf_size = 0;
|
|
if (buf_size == 0)
|
|
return 0;
|
|
|
|
if (!mp->in_sync) {
|
|
// Not in sync - find a major sync header
|
|
|
|
for (i = 0; i < buf_size; i++) {
|
|
mp->pc.state = (mp->pc.state << 8) | buf[i];
|
|
if ((mp->pc.state & 0xfffffffe) == 0xf8726fba) {
|
|
mp->in_sync = 1;
|
|
mp->bytes_left = 0;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!mp->in_sync) {
|
|
ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
|
|
return buf_size;
|
|
}
|
|
|
|
ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);
|
|
|
|
return i - 7;
|
|
}
|
|
|
|
if (mp->bytes_left == 0) {
|
|
// Find length of this packet
|
|
|
|
/* Copy overread bytes from last frame into buffer. */
|
|
for(; mp->pc.overread>0; mp->pc.overread--) {
|
|
mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
|
|
}
|
|
|
|
if (mp->pc.index + buf_size < 2) {
|
|
ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
|
|
return buf_size;
|
|
}
|
|
|
|
mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
|
|
| (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
|
|
mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
|
|
mp->bytes_left -= mp->pc.index;
|
|
}
|
|
|
|
next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;
|
|
|
|
if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
|
|
mp->bytes_left -= buf_size;
|
|
return buf_size;
|
|
}
|
|
|
|
mp->bytes_left = 0;
|
|
|
|
sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;
|
|
|
|
if (!sync_present) {
|
|
// First nibble of a frame is a parity check of the first few nibbles.
|
|
// Only check when this isn't a sync frame - syncs have a checksum.
|
|
|
|
parity_bits = 0;
|
|
for (i = -1; i < mp->num_substreams; i++) {
|
|
parity_bits ^= buf[p++];
|
|
parity_bits ^= buf[p++];
|
|
|
|
if (i < 0 || buf[p-2] & 0x80) {
|
|
parity_bits ^= buf[p++];
|
|
parity_bits ^= buf[p++];
|
|
}
|
|
}
|
|
|
|
if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
|
|
av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
|
|
goto lost_sync;
|
|
}
|
|
} else {
|
|
MLPHeaderInfo mh;
|
|
|
|
if (ff_mlp_read_major_sync(avctx, &mh, buf + 4, buf_size - 4) < 0)
|
|
goto lost_sync;
|
|
|
|
#ifdef CONFIG_AUDIO_NONSHORT
|
|
avctx->bits_per_sample = mh.group1_bits;
|
|
if (avctx->bits_per_sample > 16)
|
|
avctx->sample_fmt = SAMPLE_FMT_S32;
|
|
#endif
|
|
avctx->sample_rate = mh.group1_samplerate;
|
|
avctx->frame_size = mh.access_unit_size;
|
|
|
|
if (mh.stream_type == 0xbb) {
|
|
/* MLP stream */
|
|
avctx->channels = mlp_channels[mh.channels_mlp];
|
|
} else { /* mh.stream_type == 0xba */
|
|
/* TrueHD stream */
|
|
if (mh.channels_thd_stream2)
|
|
avctx->channels = truehd_channels(mh.channels_thd_stream2);
|
|
else
|
|
avctx->channels = truehd_channels(mh.channels_thd_stream1);
|
|
}
|
|
|
|
if (!mh.is_vbr) /* Stream is CBR */
|
|
avctx->bit_rate = mh.peak_bitrate;
|
|
|
|
mp->num_substreams = mh.num_substreams;
|
|
}
|
|
|
|
*poutbuf = buf;
|
|
*poutbuf_size = buf_size;
|
|
|
|
return next;
|
|
|
|
lost_sync:
|
|
mp->in_sync = 0;
|
|
return 1;
|
|
}
|
|
|
|
AVCodecParser mlp_parser = {
|
|
{ CODEC_ID_MLP },
|
|
sizeof(MLPParseContext),
|
|
NULL,
|
|
mlp_parse,
|
|
NULL,
|
|
};
|