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adts aac parser 

Originally committed as revision 4954 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Måns Rullgård 2006-02-08 00:50:22 +00:00
parent 79b0b66ba0
commit da46276ff8
3 changed files with 92 additions and 9 deletions
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1
libavcodec/allcodecs.c
View File

@ -622,5 +622,6 @@ PCM_CODEC(CODEC_ID_ADPCM_YAMAHA, adpcm_yamaha);
#ifdef CONFIG_DVBSUB_DECODER
av_register_codec_parser(&dvbsub_parser);
#endif
av_register_codec_parser(&aac_parser);
}

1
libavcodec/avcodec.h
View File

@ -2516,6 +2516,7 @@ extern AVCodecParser mpegaudio_parser;
extern AVCodecParser ac3_parser;
extern AVCodecParser dvdsub_parser;
extern AVCodecParser dvbsub_parser;
extern AVCodecParser aac_parser;
/* memory */
void *av_malloc(unsigned int size);

99
libavcodec/parser.c
View File

@ -727,13 +727,18 @@ static int mpegaudio_parse(AVCodecParserContext *s1,
return buf_ptr - buf;
}
/* also used for ADTS AAC */
typedef struct AC3ParseContext {
uint8_t inbuf[4096]; /* input buffer */
uint8_t *inbuf_ptr;
int frame_size;
int header_size;
int (*sync)(const uint8_t *buf, int *channels, int *sample_rate,
int *bit_rate, int *samples);
} AC3ParseContext;
#define AC3_HEADER_SIZE 7
#define AAC_HEADER_SIZE 8
static const int ac3_sample_rates[4] = {
48000, 44100, 32000, 0
@ -790,8 +795,17 @@ static const int ac3_channels[8] = {
2, 1, 2, 3, 3, 4, 4, 5
};
static int aac_sample_rates[16] = {
96000, 88200, 64000, 48000, 44100, 32000,
24000, 22050, 16000, 12000, 11025, 8000, 7350
};
static int aac_channels[8] = {
0, 1, 2, 3, 4, 5, 6, 8
};
static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
int *bit_rate)
int *bit_rate, int *samples)
{
unsigned int fscod, frmsizecod, acmod, bsid, lfeon;
GetBitContext bits;
@ -824,17 +838,70 @@ static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
*sample_rate = ac3_sample_rates[fscod];
*bit_rate = ac3_bitrates[frmsizecod] * 1000;
*channels = ac3_channels[acmod] + lfeon;
*samples = 6 * 256;
return ac3_frame_sizes[frmsizecod][fscod] * 2;
}
static int aac_sync(const uint8_t *buf, int *channels, int *sample_rate,
int *bit_rate, int *samples)
{
GetBitContext bits;
int size, rdb, ch, sr;
init_get_bits(&bits, buf, AAC_HEADER_SIZE * 8);
if(get_bits(&bits, 12) != 0xfff)
return 0;
get_bits(&bits, 1);
get_bits(&bits, 2);
get_bits(&bits, 1); /* protection_absent */
get_bits(&bits, 2);
sr = get_bits(&bits, 4);
if(!aac_sample_rates[sr])
return 0;
get_bits(&bits, 1); /* private_bit */
ch = get_bits(&bits, 3);
if(!aac_channels[ch])
return 0;
get_bits(&bits, 1); /* original/copy */
get_bits(&bits, 1); /* home */
/* adts_variable_header */
get_bits(&bits, 1); /* copyright_identification_bit */
get_bits(&bits, 1); /* copyright_identification_start */
size = get_bits(&bits, 13);
get_bits(&bits, 11); /* adts_buffer_fullness */
rdb = get_bits(&bits, 2);
*channels = aac_channels[ch];
*sample_rate = aac_sample_rates[sr];
*samples = (rdb + 1) * 1024;
*bit_rate = size * 8 * *sample_rate / *samples;
return size;
}
static int ac3_parse_init(AVCodecParserContext *s1)
{
AC3ParseContext *s = s1->priv_data;
s->inbuf_ptr = s->inbuf;
s->header_size = AC3_HEADER_SIZE;
s->sync = ac3_sync;
return 0;
}
static int aac_parse_init(AVCodecParserContext *s1)
{
AC3ParseContext *s = s1->priv_data;
s->inbuf_ptr = s->inbuf;
s->header_size = AAC_HEADER_SIZE;
s->sync = aac_sync;
return 0;
}
/* also used for ADTS AAC */
static int ac3_parse(AVCodecParserContext *s1,
AVCodecContext *avctx,
uint8_t **poutbuf, int *poutbuf_size,
@ -842,7 +909,7 @@ static int ac3_parse(AVCodecParserContext *s1,
{
AC3ParseContext *s = s1->priv_data;
const uint8_t *buf_ptr;
int len, sample_rate, bit_rate, channels;
int len, sample_rate, bit_rate, channels, samples;
*poutbuf = NULL;
*poutbuf_size = 0;
@ -851,29 +918,35 @@ static int ac3_parse(AVCodecParserContext *s1,
while (buf_size > 0) {
len = s->inbuf_ptr - s->inbuf;
if (s->frame_size == 0) {
/* no header seen : find one. We need at least 7 bytes to parse it */
len = FFMIN(AC3_HEADER_SIZE - len, buf_size);
/* no header seen : find one. We need at least s->header_size
bytes to parse it */
len = FFMIN(s->header_size - len, buf_size);
memcpy(s->inbuf_ptr, buf_ptr, len);
buf_ptr += len;
s->inbuf_ptr += len;
buf_size -= len;
if ((s->inbuf_ptr - s->inbuf) == AC3_HEADER_SIZE) {
len = ac3_sync(s->inbuf, &channels, &sample_rate, &bit_rate);
if ((s->inbuf_ptr - s->inbuf) == s->header_size) {
len = s->sync(s->inbuf, &channels, &sample_rate, &bit_rate,
&samples);
if (len == 0) {
/* no sync found : move by one byte (inefficient, but simple!) */
memmove(s->inbuf, s->inbuf + 1, AC3_HEADER_SIZE - 1);
memmove(s->inbuf, s->inbuf + 1, s->header_size - 1);
s->inbuf_ptr--;
} else {
s->frame_size = len;
/* update codec info */
avctx->sample_rate = sample_rate;
/* set channels,except if the user explicitly requests 1 or 2 channels, XXX/FIXME this is a bit ugly */
if(avctx->channels!=1 && avctx->channels!=2){
if(avctx->codec_id == CODEC_ID_AC3){
if(avctx->channels!=1 && avctx->channels!=2){
avctx->channels = channels;
}
} else {
avctx->channels = channels;
}
avctx->bit_rate = bit_rate;
avctx->frame_size = 6 * 256;
avctx->frame_size = samples;
}
}
} else {
@ -929,3 +1002,11 @@ AVCodecParser ac3_parser = {
ac3_parse,
NULL,
};
AVCodecParser aac_parser = {
{ CODEC_ID_AAC },
sizeof(AC3ParseContext),
aac_parse_init,
ac3_parse,
NULL,
};