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/* |
* LPCM codecs for PCM formats found in Video DVD streams |
* Copyright (c) 2013 Christian Schmidt |
* |
* 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 |
* LPCM codecs for PCM formats found in Video DVD streams |
*/ |
|
#include "avcodec.h" |
#include "bytestream.h" |
#include "internal.h" |
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typedef struct PCMDVDContext { |
uint32_t last_header; // Cached header to see if parsing is needed |
int block_size; // Size of a block of samples in bytes |
int last_block_size; // Size of the last block of samples in bytes |
int samples_per_block; // Number of samples per channel per block |
int groups_per_block; // Number of 20/24bit sample groups per block |
uint8_t *extra_samples; // Pointer to leftover samples from a frame |
int extra_sample_count; // Number of leftover samples in the buffer |
} PCMDVDContext; |
|
static av_cold int pcm_dvd_decode_init(AVCodecContext *avctx) |
{ |
PCMDVDContext *s = avctx->priv_data; |
|
/* Invalid header to force parsing of the first header */ |
s->last_header = -1; |
/* reserve space for 8 channels, 3 bytes/sample, 4 samples/block */ |
if (!(s->extra_samples = av_malloc(8 * 3 * 4))) |
return AVERROR(ENOMEM); |
|
return 0; |
} |
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static av_cold int pcm_dvd_decode_uninit(AVCodecContext *avctx) |
{ |
PCMDVDContext *s = avctx->priv_data; |
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av_freep(&s->extra_samples); |
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return 0; |
} |
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static int pcm_dvd_parse_header(AVCodecContext *avctx, const uint8_t *header) |
{ |
/* no traces of 44100 and 32000Hz in any commercial software or player */ |
static const uint32_t frequencies[4] = { 48000, 96000, 44100, 32000 }; |
PCMDVDContext *s = avctx->priv_data; |
int header_int = (header[0] & 0xe0) | (header[1] << 8) | (header[2] << 16); |
|
/* early exit if the header didn't change apart from the frame number */ |
if (s->last_header == header_int) |
return 0; |
|
if (avctx->debug & FF_DEBUG_PICT_INFO) |
av_dlog(avctx, "pcm_dvd_parse_header: header = %02x%02x%02x\n", |
header[0], header[1], header[2]); |
/* |
* header[0] emphasis (1), muse(1), reserved(1), frame number(5) |
* header[1] quant (2), freq(2), reserved(1), channels(3) |
* header[2] dynamic range control (0x80 = off) |
*/ |
|
/* Discard potentially existing leftover samples from old channel layout */ |
s->extra_sample_count = 0; |
|
/* get the sample depth and derive the sample format from it */ |
avctx->bits_per_coded_sample = 16 + (header[1] >> 6 & 3) * 4; |
if (avctx->bits_per_coded_sample == 28) { |
av_log(avctx, AV_LOG_ERROR, |
"PCM DVD unsupported sample depth %i\n", |
avctx->bits_per_coded_sample); |
return AVERROR_INVALIDDATA; |
} |
avctx->sample_fmt = avctx->bits_per_coded_sample == 16 ? AV_SAMPLE_FMT_S16 |
: AV_SAMPLE_FMT_S32; |
avctx->bits_per_raw_sample = avctx->bits_per_coded_sample; |
|
/* get the sample rate */ |
avctx->sample_rate = frequencies[header[1] >> 4 & 3]; |
|
/* get the number of channels */ |
avctx->channels = 1 + (header[1] & 7); |
/* calculate the bitrate */ |
avctx->bit_rate = avctx->channels * |
avctx->sample_rate * |
avctx->bits_per_coded_sample; |
|
/* 4 samples form a group in 20/24bit PCM on DVD Video. |
* A block is formed by the number of groups that are |
* needed to complete a set of samples for each channel. */ |
if (avctx->bits_per_coded_sample == 16) { |
s->samples_per_block = 1; |
s->block_size = avctx->channels * 2; |
} else { |
switch (avctx->channels) { |
case 1: |
case 2: |
case 4: |
/* one group has all the samples needed */ |
s->block_size = 4 * avctx->bits_per_coded_sample / 8; |
s->samples_per_block = 4 / avctx->channels; |
s->groups_per_block = 1; |
break; |
case 8: |
/* two groups have all the samples needed */ |
s->block_size = 8 * avctx->bits_per_coded_sample / 8; |
s->samples_per_block = 1; |
s->groups_per_block = 2; |
break; |
default: |
/* need avctx->channels groups */ |
s->block_size = 4 * avctx->channels * |
avctx->bits_per_coded_sample / 8; |
s->samples_per_block = 4; |
s->groups_per_block = avctx->channels; |
break; |
} |
} |
|
if (avctx->debug & FF_DEBUG_PICT_INFO) |
av_dlog(avctx, |
"pcm_dvd_parse_header: %d channels, %d bits per sample, %d Hz, %d bit/s\n", |
avctx->channels, avctx->bits_per_coded_sample, |
avctx->sample_rate, avctx->bit_rate); |
|
s->last_header = header_int; |
|
return 0; |
} |
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static void *pcm_dvd_decode_samples(AVCodecContext *avctx, const uint8_t *src, |
void *dst, int blocks) |
{ |
PCMDVDContext *s = avctx->priv_data; |
int16_t *dst16 = dst; |
int32_t *dst32 = dst; |
GetByteContext gb; |
int i; |
uint8_t t; |
int samples; |
|
bytestream2_init(&gb, src, blocks * s->block_size); |
switch (avctx->bits_per_coded_sample) { |
case 16: |
#if HAVE_BIGENDIAN |
bytestream2_get_buffer(&gb, dst16, blocks * s->block_size); |
dst16 += blocks * s->block_size / 2; |
#else |
samples = blocks * avctx->channels; |
do { |
*dst16++ = bytestream2_get_be16u(&gb); |
} while (--samples); |
#endif |
return dst16; |
case 20: |
if (avctx->channels == 1) { |
do { |
for (i = 2; i; i--) { |
dst32[0] = bytestream2_get_be16u(&gb) << 16; |
dst32[1] = bytestream2_get_be16u(&gb) << 16; |
t = bytestream2_get_byteu(&gb); |
*dst32++ += (t & 0xf0) << 8; |
*dst32++ += (t & 0x0f) << 12; |
} |
} while (--blocks); |
} else { |
do { |
for (i = s->groups_per_block; i; i--) { |
dst32[0] = bytestream2_get_be16u(&gb) << 16; |
dst32[1] = bytestream2_get_be16u(&gb) << 16; |
dst32[2] = bytestream2_get_be16u(&gb) << 16; |
dst32[3] = bytestream2_get_be16u(&gb) << 16; |
t = bytestream2_get_byteu(&gb); |
*dst32++ += (t & 0xf0) << 8; |
*dst32++ += (t & 0x0f) << 12; |
t = bytestream2_get_byteu(&gb); |
*dst32++ += (t & 0xf0) << 8; |
*dst32++ += (t & 0x0f) << 12; |
} |
} while (--blocks); |
} |
return dst32; |
case 24: |
if (avctx->channels == 1) { |
do { |
for (i = 2; i; i--) { |
dst32[0] = bytestream2_get_be16u(&gb) << 16; |
dst32[1] = bytestream2_get_be16u(&gb) << 16; |
*dst32++ += bytestream2_get_byteu(&gb) << 8; |
*dst32++ += bytestream2_get_byteu(&gb) << 8; |
} |
} while (--blocks); |
} else { |
do { |
for (i = s->groups_per_block; i; i--) { |
dst32[0] = bytestream2_get_be16u(&gb) << 16; |
dst32[1] = bytestream2_get_be16u(&gb) << 16; |
dst32[2] = bytestream2_get_be16u(&gb) << 16; |
dst32[3] = bytestream2_get_be16u(&gb) << 16; |
*dst32++ += bytestream2_get_byteu(&gb) << 8; |
*dst32++ += bytestream2_get_byteu(&gb) << 8; |
*dst32++ += bytestream2_get_byteu(&gb) << 8; |
*dst32++ += bytestream2_get_byteu(&gb) << 8; |
} |
} while (--blocks); |
} |
return dst32; |
default: |
return NULL; |
} |
} |
|
static int pcm_dvd_decode_frame(AVCodecContext *avctx, void *data, |
int *got_frame_ptr, AVPacket *avpkt) |
{ |
AVFrame *frame = data; |
const uint8_t *src = avpkt->data; |
int buf_size = avpkt->size; |
PCMDVDContext *s = avctx->priv_data; |
int retval; |
int blocks; |
void *dst; |
|
if (buf_size < 3) { |
av_log(avctx, AV_LOG_ERROR, "PCM packet too small\n"); |
return AVERROR_INVALIDDATA; |
} |
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if ((retval = pcm_dvd_parse_header(avctx, src))) |
return retval; |
if (s->last_block_size != s->block_size) { |
av_log(avctx, AV_LOG_WARNING, "block_size has changed\n"); |
s->extra_sample_count = 0; |
} |
s->last_block_size = s->block_size; |
src += 3; |
buf_size -= 3; |
|
blocks = (buf_size + s->extra_sample_count) / s->block_size; |
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/* get output buffer */ |
frame->nb_samples = blocks * s->samples_per_block; |
if ((retval = ff_get_buffer(avctx, frame, 0)) < 0) |
return retval; |
dst = frame->data[0]; |
|
/* consume leftover samples from last packet */ |
if (s->extra_sample_count) { |
int missing_samples = s->block_size - s->extra_sample_count; |
if (buf_size >= missing_samples) { |
memcpy(s->extra_samples + s->extra_sample_count, src, |
missing_samples); |
dst = pcm_dvd_decode_samples(avctx, s->extra_samples, dst, 1); |
src += missing_samples; |
buf_size -= missing_samples; |
s->extra_sample_count = 0; |
blocks--; |
} else { |
/* new packet still doesn't have enough samples */ |
memcpy(s->extra_samples + s->extra_sample_count, src, buf_size); |
s->extra_sample_count += buf_size; |
return avpkt->size; |
} |
} |
|
/* decode remaining complete samples */ |
if (blocks) { |
pcm_dvd_decode_samples(avctx, src, dst, blocks); |
buf_size -= blocks * s->block_size; |
} |
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/* store leftover samples */ |
if (buf_size) { |
src += blocks * s->block_size; |
memcpy(s->extra_samples, src, buf_size); |
s->extra_sample_count = buf_size; |
} |
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*got_frame_ptr = 1; |
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return avpkt->size; |
} |
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AVCodec ff_pcm_dvd_decoder = { |
.name = "pcm_dvd", |
.long_name = NULL_IF_CONFIG_SMALL("PCM signed 16|20|24-bit big-endian for DVD media"), |
.type = AVMEDIA_TYPE_AUDIO, |
.id = AV_CODEC_ID_PCM_DVD, |
.priv_data_size = sizeof(PCMDVDContext), |
.init = pcm_dvd_decode_init, |
.decode = pcm_dvd_decode_frame, |
.close = pcm_dvd_decode_uninit, |
.capabilities = CODEC_CAP_DR1, |
.sample_fmts = (const enum AVSampleFormat[]) { |
AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_NONE |
} |
}; |