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avcodec/flacdec: Attempt to auto-detect old buggy flac 

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2015-05-17 13:10:33 +02:00
parent 83356cf6cc
commit b6fcb2bb6d
1 changed files with 29 additions and 0 deletions
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29
libavcodec/flacdec.c
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@ -315,6 +315,33 @@ static int decode_subframe_fixed(FLACContext *s, int32_t *decoded,
return 0; return 0;
} }
static void lpc_analyze_remodulate(int32_t *decoded, const int coeffs[32],
int order, int qlevel, int len, int bps)
{
int i, j;
int ebps = 1 << (bps-1);
unsigned sigma = 0;
for (i = order; i < len; i++)
sigma |= decoded[i] + ebps;
if (sigma < 2*ebps)
return;
for (i = len - 1; i >= order; i--) {
int64_t p = 0;
for (j = 0; j < order; j++)
p += coeffs[j] * (int64_t)decoded[i-order+j];
decoded[i] -= p >> qlevel;
}
for (i = order; i < len; i++, decoded++) {
int32_t p = 0;
for (j = 0; j < order; j++)
p += coeffs[j] * (uint32_t)decoded[j];
decoded[j] += p >> qlevel;
}
}
static int decode_subframe_lpc(FLACContext *s, int32_t *decoded, int pred_order, static int decode_subframe_lpc(FLACContext *s, int32_t *decoded, int pred_order,
int bps) int bps)
{ {
@ -352,6 +379,8 @@ static int decode_subframe_lpc(FLACContext *s, int32_t *decoded, int pred_order,
s->dsp.lpc16(decoded, coeffs, pred_order, qlevel, s->blocksize); s->dsp.lpc16(decoded, coeffs, pred_order, qlevel, s->blocksize);
} else { } else {
s->dsp.lpc32(decoded, coeffs, pred_order, qlevel, s->blocksize); s->dsp.lpc32(decoded, coeffs, pred_order, qlevel, s->blocksize);
if (s->flac_stream_info.bps <= 16)
lpc_analyze_remodulate(decoded, coeffs, pred_order, qlevel, s->blocksize, bps);
} }
return 0; return 0;