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don't need to synchronize in the decoder. the parser does that already.

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Originally committed as revision 9772 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-07-21 13:56:04 +00:00
parent de34875c75
commit 9ef6039043
1 changed files with 1 additions and 28 deletions
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29
libavcodec/ac3dec.c
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@ -320,24 +320,6 @@ static int ac3_decode_init(AVCodecContext *avctx)
} }
/*********** END INIT FUNCTIONS ***********/ /*********** END INIT FUNCTIONS ***********/
/* Synchronize to ac3 bitstream.
* This function searches for the syncword '0xb77'.
*
* @param buf Pointer to "probable" ac3 bitstream buffer
* @param buf_size Size of buffer
* @return Returns the position where syncword is found, -1 if no syncword is found
*/
static int ac3_synchronize(uint8_t *buf, int buf_size)
{
int i;
for (i = 0; i < buf_size - 1; i++)
if (buf[i] == 0x0b && buf[i + 1] == 0x77)
return i;
return -1;
}
/* Parse the 'sync_info' from the ac3 bitstream. /* Parse the 'sync_info' from the ac3 bitstream.
* This function extracts the sync_info from ac3 bitstream. * This function extracts the sync_info from ac3 bitstream.
* GetBitContext within AC3DecodeContext must point to * GetBitContext within AC3DecodeContext must point to
@ -1645,7 +1627,6 @@ static inline int16_t convert(int32_t i)
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size) static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
{ {
AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data; AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
int frame_start;
int16_t *out_samples = (int16_t *)data; int16_t *out_samples = (int16_t *)data;
int i, j, k, start; int i, j, k, start;
int32_t *int_ptr[6]; int32_t *int_ptr[6];
@ -1653,16 +1634,8 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
for (i = 0; i < 6; i++) for (i = 0; i < 6; i++)
int_ptr[i] = (int32_t *)(&ctx->output[i]); int_ptr[i] = (int32_t *)(&ctx->output[i]);
//Synchronize the frame.
frame_start = ac3_synchronize(buf, buf_size);
if (frame_start == -1) {
av_log(avctx, AV_LOG_ERROR, "frame is not synchronized\n");
*data_size = 0;
return buf_size;
}
//Initialize the GetBitContext with the start of valid AC3 Frame. //Initialize the GetBitContext with the start of valid AC3 Frame.
init_get_bits(&(ctx->gb), buf + frame_start, (buf_size - frame_start) * 8); init_get_bits(&ctx->gb, buf, buf_size * 8);
//Parse the syncinfo. //Parse the syncinfo.
//If 'fscod' or 'bsid' is not valid the decoder shall mute as per the standard. //If 'fscod' or 'bsid' is not valid the decoder shall mute as per the standard.