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Move AC3 header parsing code together with the rest of the AC3 parsing code.

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Originally committed as revision 8739 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Diego Biurrun
2007-04-15 12:32:36 +00:00
parent d3255f6fd8
commit 98d0205145
6 changed files with 66 additions and 65 deletions
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51
libavcodec/parser.c
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@ -22,7 +22,6 @@
#include "avcodec.h"
#include "mpegvideo.h"
#include "mpegaudio.h"
#include "ac3.h"
#include "parser.h"
AVCodecParser *av_first_parser = NULL;
@ -605,6 +604,56 @@ static const int aac_channels[8] = {
#endif
#ifdef CONFIG_AC3_PARSER
int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr)
{
GetBitContext gbc;
memset(hdr, 0, sizeof(*hdr));
init_get_bits(&gbc, buf, 54);
hdr->sync_word = get_bits(&gbc, 16);
if(hdr->sync_word != 0x0B77)
return -1;
/* read ahead to bsid to make sure this is AC-3, not E-AC-3 */
hdr->bsid = show_bits_long(&gbc, 29) & 0x1F;
if(hdr->bsid > 10)
return -2;
hdr->crc1 = get_bits(&gbc, 16);
hdr->fscod = get_bits(&gbc, 2);
if(hdr->fscod == 3)
return -3;
hdr->frmsizecod = get_bits(&gbc, 6);
if(hdr->frmsizecod > 37)
return -4;
skip_bits(&gbc, 5); // skip bsid, already got it
hdr->bsmod = get_bits(&gbc, 3);
hdr->acmod = get_bits(&gbc, 3);
if((hdr->acmod & 1) && hdr->acmod != 1) {
hdr->cmixlev = get_bits(&gbc, 2);
}
if(hdr->acmod & 4) {
hdr->surmixlev = get_bits(&gbc, 2);
}
if(hdr->acmod == 2) {
hdr->dsurmod = get_bits(&gbc, 2);
}
hdr->lfeon = get_bits1(&gbc);
hdr->halfratecod = FFMAX(hdr->bsid, 8) - 8;
hdr->sample_rate = ff_ac3_freqs[hdr->fscod] >> hdr->halfratecod;
hdr->bit_rate = (ff_ac3_bitratetab[hdr->frmsizecod>>1] * 1000) >> hdr->halfratecod;
hdr->channels = ff_ac3_channels[hdr->acmod] + hdr->lfeon;
hdr->frame_size = ff_ac3_frame_sizes[hdr->frmsizecod][hdr->fscod] * 2;
return 0;
}
static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
int *bit_rate, int *samples)
{