diff options
| -rw-r--r-- | libavcodec/flac.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/libavcodec/flac.c b/libavcodec/flac.c index 74b245d0e5..d8e8813d9e 100644 --- a/libavcodec/flac.c +++ b/libavcodec/flac.c @@ -359,10 +359,25 @@ static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order) s->decoded[channel][i] += sum >> qlevel; } } else { - int sum; - for (i = pred_order; i < s->blocksize; i++) + for (i = pred_order; i < s->blocksize-1; i += 2) { - sum = 0; + int c = coeffs[pred_order-1]; + int s0 = c * s->decoded[channel][i-pred_order]; + int s1 = 0; + for (j = pred_order-1; j > 0; j--) + { + int d = s->decoded[channel][i-j]; + s1 += c*d; + c = coeffs[j-1]; + s0 += c*d; + } + s0 = s->decoded[channel][i] += s0 >> qlevel; + s1 += c * s0; + s->decoded[channel][i+1] += s1 >> qlevel; + } + if (i < s->blocksize) + { + int sum = 0; for (j = 0; j < pred_order; j++) sum += coeffs[j] * s->decoded[channel][i-j-1]; s->decoded[channel][i] += sum >> qlevel; |