mirror of https://git.ffmpeg.org/ffmpeg.git
flacdec: reverse lpc coeff order, simplify filter
Reversing the lpc coefficient order simplifies indexing in the filter. Signed-off-by: Mans Rullgard <mans@mansr.com>
This commit is contained in:
parent
9f97af2688
commit
bf1cf4d5a5
|
@ -321,7 +321,7 @@ static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order,
|
||||||
}
|
}
|
||||||
|
|
||||||
for (i = 0; i < pred_order; i++) {
|
for (i = 0; i < pred_order; i++) {
|
||||||
coeffs[i] = get_sbits(&s->gb, coeff_prec);
|
coeffs[pred_order - i - 1] = get_sbits(&s->gb, coeff_prec);
|
||||||
}
|
}
|
||||||
|
|
||||||
if (decode_residuals(s, channel, pred_order) < 0)
|
if (decode_residuals(s, channel, pred_order) < 0)
|
||||||
|
|
|
@ -45,27 +45,26 @@ static void flac_lpc_16_c(int32_t *decoded, const int coeffs[32],
|
||||||
{
|
{
|
||||||
int i, j;
|
int i, j;
|
||||||
|
|
||||||
for (i = pred_order; i < len - 1; i += 2) {
|
for (i = pred_order; i < len - 1; i += 2, decoded += 2) {
|
||||||
int c;
|
int c = coeffs[0];
|
||||||
int d = decoded[i-pred_order];
|
int d = decoded[0];
|
||||||
int s0 = 0, s1 = 0;
|
int s0 = 0, s1 = 0;
|
||||||
for (j = pred_order-1; j > 0; j--) {
|
for (j = 1; j < pred_order; j++) {
|
||||||
|
s0 += c*d;
|
||||||
|
d = decoded[j];
|
||||||
|
s1 += c*d;
|
||||||
c = coeffs[j];
|
c = coeffs[j];
|
||||||
s0 += c*d;
|
|
||||||
d = decoded[i-j];
|
|
||||||
s1 += c*d;
|
|
||||||
}
|
}
|
||||||
c = coeffs[0];
|
|
||||||
s0 += c*d;
|
s0 += c*d;
|
||||||
d = decoded[i] += s0 >> qlevel;
|
d = decoded[j] += s0 >> qlevel;
|
||||||
s1 += c*d;
|
s1 += c*d;
|
||||||
decoded[i+1] += s1 >> qlevel;
|
decoded[j + 1] += s1 >> qlevel;
|
||||||
}
|
}
|
||||||
if (i < len) {
|
if (i < len) {
|
||||||
int sum = 0;
|
int sum = 0;
|
||||||
for (j = 0; j < pred_order; j++)
|
for (j = 0; j < pred_order; j++)
|
||||||
sum += coeffs[j] * decoded[i-j-1];
|
sum += coeffs[j] * decoded[j];
|
||||||
decoded[i] += sum >> qlevel;
|
decoded[j] += sum >> qlevel;
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
|
@ -74,11 +73,11 @@ static void flac_lpc_32_c(int32_t *decoded, const int coeffs[32],
|
||||||
{
|
{
|
||||||
int i, j;
|
int i, j;
|
||||||
|
|
||||||
for (i = pred_order; i < len; i++) {
|
for (i = pred_order; i < len; i++, decoded++) {
|
||||||
int64_t sum = 0;
|
int64_t sum = 0;
|
||||||
for (j = 0; j < pred_order; j++)
|
for (j = 0; j < pred_order; j++)
|
||||||
sum += (int64_t)coeffs[j] * decoded[i-j-1];
|
sum += (int64_t)coeffs[j] * decoded[j];
|
||||||
decoded[i] += sum >> qlevel;
|
decoded[j] += sum >> qlevel;
|
||||||
}
|
}
|
||||||
|
|
||||||
}
|
}
|
||||||
|
|
Loading…
Reference in New Issue