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FFmpeg/libavcodec/mlp_parser.c
Vittorio Giovara 970c76f322 mlp_parser: Drop in-parser downmix functionality 
request_channel_layout is a decoder option and it makes no sense
to have it in a parser.

This feature was needed in the past when the decoder was allowed
to reuse the avctx from the demuxer. Nowadays the decoder receives
only the parameters from it, already containing the real channel
layout (and the correct request_channel_layout option).

After initialization the decoder overwrites the channel layout
with the downmixed one that is actually output, so there is no need
to preserve this functionality in the parser.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
2017-04-27 14:19:54 -04:00

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/*
* MLP parser
* Copyright (c) 2007 Ian Caulfield
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* MLP parser
*/
#include <stdint.h>
#include "libavutil/channel_layout.h"
#include "libavutil/crc.h"
#include "libavutil/internal.h"
#include "bitstream.h"
#include "parser.h"
#include "mlp_parser.h"
#include "mlp.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 uint64_t mlp_layout[32] = {
AV_CH_LAYOUT_MONO,
AV_CH_LAYOUT_STEREO,
AV_CH_LAYOUT_2_1,
AV_CH_LAYOUT_2_2,
AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY,
AV_CH_LAYOUT_2_1|AV_CH_LOW_FREQUENCY,
AV_CH_LAYOUT_2_2|AV_CH_LOW_FREQUENCY,
AV_CH_LAYOUT_SURROUND,
AV_CH_LAYOUT_4POINT0,
AV_CH_LAYOUT_5POINT0,
AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
AV_CH_LAYOUT_5POINT1,
AV_CH_LAYOUT_4POINT0,
AV_CH_LAYOUT_5POINT0,
AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
AV_CH_LAYOUT_5POINT1,
AV_CH_LAYOUT_2_2|AV_CH_LOW_FREQUENCY,
AV_CH_LAYOUT_5POINT0,
AV_CH_LAYOUT_5POINT1,
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 const uint64_t thd_layout[13] = {
AV_CH_FRONT_LEFT|AV_CH_FRONT_RIGHT, // LR
AV_CH_FRONT_CENTER, // C
AV_CH_LOW_FREQUENCY, // LFE
AV_CH_SIDE_LEFT|AV_CH_SIDE_RIGHT, // LRs
AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT, // LRvh
AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER, // LRc
AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT, // LRrs
AV_CH_BACK_CENTER, // Cs
AV_CH_TOP_CENTER, // Ts
AV_CH_SURROUND_DIRECT_LEFT|AV_CH_SURROUND_DIRECT_RIGHT, // LRsd
AV_CH_WIDE_LEFT|AV_CH_WIDE_RIGHT, // LRw
AV_CH_TOP_FRONT_CENTER, // Cvh
AV_CH_LOW_FREQUENCY_2, // LFE2
};
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 uint64_t truehd_layout(int chanmap)
{
int i;
uint64_t layout = 0;
for (i = 0; i < 13; i++)
layout |= thd_layout[i] * ((chanmap >> i) & 1);
return layout;
}
static int mlp_get_major_sync_size(const uint8_t * buf, int bufsize)
{
int has_extension, extensions = 0;
int size = 28;
if (bufsize < 28)
return -1;
if (AV_RB32(buf) == 0xf8726fba) {
has_extension = buf[25] & 1;
if (has_extension) {
extensions = buf[26] >> 4;
size += 2 + extensions * 2;
}
}
return size;
}
/** 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.
* bc must be a freshly-initialized BitstreamContext with no bits read.
*/
int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, BitstreamContext *bc)
{
int ratebits, channel_arrangement, header_size;
uint16_t checksum;
assert(bitstream_tell(bc) == 0);
header_size = mlp_get_major_sync_size(bc->buffer, bc->size_in_bits >> 3);
if (header_size < 0 || bc->size_in_bits < header_size << 3) {
av_log(log, AV_LOG_ERROR, "packet too short, unable to read major sync\n");
return -1;
}
checksum = ff_mlp_checksum16(bc->buffer, header_size - 2);
if (checksum != AV_RL16(bc->buffer + header_size - 2)) {
av_log(log, AV_LOG_ERROR, "major sync info header checksum error\n");
return AVERROR_INVALIDDATA;
}
if (bitstream_read(bc, 24) != 0xf8726f) /* Sync words */
return AVERROR_INVALIDDATA;
mh->stream_type = bitstream_read(bc, 8);
mh->header_size = header_size;
if (mh->stream_type == 0xbb) {
mh->group1_bits = mlp_quants[bitstream_read(bc, 4)];
mh->group2_bits = mlp_quants[bitstream_read(bc, 4)];
ratebits = bitstream_read(bc, 4);
mh->group1_samplerate = mlp_samplerate(ratebits);
mh->group2_samplerate = mlp_samplerate(bitstream_read(bc, 4));
bitstream_skip(bc, 11);
channel_arrangement = bitstream_read(bc, 5);
mh->channels_mlp = mlp_channels[channel_arrangement];
mh->channel_layout_mlp = mlp_layout[channel_arrangement];
} else if (mh->stream_type == 0xba) {
mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
mh->group2_bits = 0;
ratebits = bitstream_read(bc, 4);
mh->group1_samplerate = mlp_samplerate(ratebits);
mh->group2_samplerate = 0;
bitstream_skip(bc, 4);
mh->channel_modifier_thd_stream0 = bitstream_read(bc, 2);
mh->channel_modifier_thd_stream1 = bitstream_read(bc, 2);
channel_arrangement = bitstream_read(bc, 5);
mh->channels_thd_stream1 = truehd_channels(channel_arrangement);
mh->channel_layout_thd_stream1 = truehd_layout(channel_arrangement);
mh->channel_modifier_thd_stream2 = bitstream_read(bc, 2);
channel_arrangement = bitstream_read(bc, 13);
mh->channels_thd_stream2 = truehd_channels(channel_arrangement);
mh->channel_layout_thd_stream2 = truehd_layout(channel_arrangement);
} else
return AVERROR_INVALIDDATA;
mh->access_unit_size = 40 << (ratebits & 7);
mh->access_unit_size_pow2 = 64 << (ratebits & 7);
bitstream_skip(bc, 48);
mh->is_vbr = bitstream_read_bit(bc);
mh->peak_bitrate = (bitstream_read(bc, 15) * mh->group1_samplerate + 8) >> 4;
mh->num_substreams = bitstream_read(bc, 4);
bitstream_skip(bc, 4 + (header_size - 17) * 8);
return 0;
}
typedef struct MLPParseContext
{
ParseContext pc;
int bytes_left;
int in_sync;
int num_substreams;
} MLPParseContext;
static av_cold int mlp_init(AVCodecParserContext *s)
{
ff_mlp_init_crc();
return 0;
}
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 &&
// ignore if we do not have the data for the start of header
mp->pc.index + i >= 7) {
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) {
/* The first nibble of a frame is a parity check of the 4-byte
* access unit header and all the 2- or 4-byte substream headers. */
// 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 {
BitstreamContext bc;
MLPHeaderInfo mh;
bitstream_init8(&bc, buf + 4, buf_size - 4);
if (ff_mlp_read_major_sync(avctx, &mh, &bc) < 0)
goto lost_sync;
avctx->bits_per_raw_sample = mh.group1_bits;
if (avctx->bits_per_raw_sample > 16)
avctx->sample_fmt = AV_SAMPLE_FMT_S32;
else
avctx->sample_fmt = AV_SAMPLE_FMT_S16;
avctx->sample_rate = mh.group1_samplerate;
s->duration = mh.access_unit_size;
if (mh.stream_type == 0xbb) {
/* MLP stream */
avctx->channels = mh.channels_mlp;
avctx->channel_layout = mh.channel_layout_mlp;
} else { /* mh.stream_type == 0xba */
/* TrueHD stream */
if (!mh.channels_thd_stream2) {
avctx->channels = mh.channels_thd_stream1;
avctx->channel_layout = mh.channel_layout_thd_stream1;
} else {
avctx->channels = mh.channels_thd_stream2;
avctx->channel_layout = mh.channel_layout_thd_stream2;
}
}
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 ff_mlp_parser = {
.codec_ids = { AV_CODEC_ID_MLP, AV_CODEC_ID_TRUEHD },
.priv_data_size = sizeof(MLPParseContext),
.parser_init = mlp_init,
.parser_parse = mlp_parse,
.parser_close = ff_parse_close,
};
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