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better AC3 header error reporting 

Originally committed as revision 10496 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-09-15 02:41:24 +00:00
parent d5b7144e1f
commit 3df880934e
3 changed files with 32 additions and 9 deletions
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8
libavcodec/ac3_parser.c
View File

@ -44,21 +44,21 @@ int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr)
hdr->sync_word = get_bits(&gbc, 16);
if(hdr->sync_word != 0x0B77)
return -1;
return AC3_PARSE_ERROR_SYNC;
/* 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;
return AC3_PARSE_ERROR_BSID;
hdr->crc1 = get_bits(&gbc, 16);
hdr->fscod = get_bits(&gbc, 2);
if(hdr->fscod == 3)
return -3;
return AC3_PARSE_ERROR_SAMPLE_RATE;
hdr->frmsizecod = get_bits(&gbc, 6);
if(hdr->frmsizecod > 37)
return -4;
return AC3_PARSE_ERROR_FRAME_SIZE;
skip_bits(&gbc, 5); // skip bsid, already got it

7
libavcodec/ac3_parser.h
View File

@ -25,6 +25,13 @@
#include "ac3.h"
typedef enum {
AC3_PARSE_ERROR_SYNC = -1,
AC3_PARSE_ERROR_BSID = -2,
AC3_PARSE_ERROR_SAMPLE_RATE = -3,
AC3_PARSE_ERROR_FRAME_SIZE = -4,
} AC3ParseError;
/**
* Parses AC-3 frame header.
* Parses the header up to the lfeon element, which is the first 52 or 54 bits

26
libavcodec/ac3dec.c
View File

@ -1089,16 +1089,32 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
{
AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
int16_t *out_samples = (int16_t *)data;
int i, blk, ch;
int i, blk, ch, err;
/* initialize the GetBitContext with the start of valid AC-3 Frame */
init_get_bits(&ctx->gb, buf, buf_size * 8);
/* parse the syncinfo */
if (ac3_parse_header(ctx)) {
av_log(avctx, AV_LOG_ERROR, "\n");
*data_size = 0;
return buf_size;
err = ac3_parse_header(ctx);
if(err) {
switch(err) {
case AC3_PARSE_ERROR_SYNC:
av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
break;
case AC3_PARSE_ERROR_BSID:
av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
break;
case AC3_PARSE_ERROR_SAMPLE_RATE:
av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
break;
case AC3_PARSE_ERROR_FRAME_SIZE:
av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
break;
default:
av_log(avctx, AV_LOG_ERROR, "invalid header\n");
break;
}
return -1;
}
avctx->sample_rate = ctx->sampling_rate;