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lpc: correctly apply windowing to the samples in the float-only lpc

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Also change the window to Hamming (using coefficient which make it
a Hanning).

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
This commit is contained in:
Rostislav Pehlivanov 2015-09-19 16:25:58 +01:00
parent 9db6c8815d
commit 0cfdaf45c4
2 changed files with 7 additions and 5 deletions
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10
libavcodec/lpc.c
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@ -173,11 +173,13 @@ double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len,
int i;
double signal = 0.0f, avg_err = 0.0f;
double autoc[MAX_LPC_ORDER+1] = {0}, error[MAX_LPC_ORDER+1] = {0};
const double c = (len - 1)/2.0f;
const double a = 0.5f, b = 1.0f - a;
/* Welch window */
for (i = 0; i < len; i++)
s->windowed_samples[i] = 1.0f - ((samples[i]-c)/c)*((samples[i]-c)/c);
/* Apply windowing */
for (i = 0; i < len; i++) {
double weight = a - b*cos((2*M_PI*i)/(len - 1));
s->windowed_samples[i] = weight*samples[i];
}
s->lpc_compute_autocorr(s->windowed_samples, len, order, autoc);
signal = autoc[0];

2
tests/fate/aac.mak
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@ -181,7 +181,7 @@ fate-aac-tns-encode: CMD = enc_dec_pcm adts wav s16le $(TARGET_SAMPLES)/audio-re
fate-aac-tns-encode: CMP = stddev
fate-aac-tns-encode: REF = $(SAMPLES)/audio-reference/luckynight_2ch_44kHz_s16.wav
fate-aac-tns-encode: CMP_SHIFT = -4096
fate-aac-tns-encode: CMP_TARGET = 650.28
fate-aac-tns-encode: CMP_TARGET = 650.37
fate-aac-tns-encode: FUZZ = 2.8
fate-aac-tns-encode: SIZE_TOLERANCE = 3560