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split up header parsing function 

Originally committed as revision 13705 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2008-06-07 22:30:51 +00:00
parent da04be10a2
commit 4397d95ce0
1 changed files with 43 additions and 32 deletions
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75
libavcodec/ac3dec.c
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@ -235,10 +235,50 @@ static av_cold int ac3_decode_init(AVCodecContext *avctx)
* start of the synchronized ac3 bitstream. * start of the synchronized ac3 bitstream.
*/ */
static int ac3_parse_header(AC3DecodeContext *s) static int ac3_parse_header(AC3DecodeContext *s)
{
GetBitContext *gbc = &s->gbc;
int i;
/* read the rest of the bsi. read twice for dual mono mode. */
i = !(s->channel_mode);
do {
skip_bits(gbc, 5); // skip dialog normalization
if (get_bits1(gbc))
skip_bits(gbc, 8); //skip compression
if (get_bits1(gbc))
skip_bits(gbc, 8); //skip language code
if (get_bits1(gbc))
skip_bits(gbc, 7); //skip audio production information
} while (i--);
skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
/* skip the timecodes (or extra bitstream information for Alternate Syntax)
TODO: read & use the xbsi1 downmix levels */
if (get_bits1(gbc))
skip_bits(gbc, 14); //skip timecode1 / xbsi1
if (get_bits1(gbc))
skip_bits(gbc, 14); //skip timecode2 / xbsi2
/* skip additional bitstream info */
if (get_bits1(gbc)) {
i = get_bits(gbc, 6);
do {
skip_bits(gbc, 8);
} while(i--);
}
return 0;
}
/**
* Common function to parse AC3 or E-AC3 frame header
*/
static int parse_frame_header(AC3DecodeContext *s)
{ {
AC3HeaderInfo hdr; AC3HeaderInfo hdr;
GetBitContext *gbc = &s->gbc; GetBitContext *gbc = &s->gbc;
int err, i; int err;
err = ff_ac3_parse_header(gbc, &hdr); err = ff_ac3_parse_header(gbc, &hdr);
if(err) if(err)
@ -271,36 +311,7 @@ static int ac3_parse_header(AC3DecodeContext *s)
s->channel_in_cpl[s->lfe_ch] = 0; s->channel_in_cpl[s->lfe_ch] = 0;
} }
/* read the rest of the bsi. read twice for dual mono mode. */ return ac3_parse_header(s);
i = !(s->channel_mode);
do {
skip_bits(gbc, 5); // skip dialog normalization
if (get_bits1(gbc))
skip_bits(gbc, 8); //skip compression
if (get_bits1(gbc))
skip_bits(gbc, 8); //skip language code
if (get_bits1(gbc))
skip_bits(gbc, 7); //skip audio production information
} while (i--);
skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
/* skip the timecodes (or extra bitstream information for Alternate Syntax)
TODO: read & use the xbsi1 downmix levels */
if (get_bits1(gbc))
skip_bits(gbc, 14); //skip timecode1 / xbsi1
if (get_bits1(gbc))
skip_bits(gbc, 14); //skip timecode2 / xbsi2
/* skip additional bitstream info */
if (get_bits1(gbc)) {
i = get_bits(gbc, 6);
do {
skip_bits(gbc, 8);
} while(i--);
}
return 0;
} }
/** /**
@ -1081,7 +1092,7 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
/* parse the syncinfo */ /* parse the syncinfo */
*data_size = 0; *data_size = 0;
err = ac3_parse_header(s); err = parse_frame_header(s);
/* check that reported frame size fits in input buffer */ /* check that reported frame size fits in input buffer */
if(s->frame_size > buf_size) { if(s->frame_size > buf_size) {