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saturate MDCT output

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This commit is contained in:
Jean-Marc Valin 2016-07-21 19:48:55 -04:00
parent 273906404c
commit 382ab797cf
2 changed files with 7 additions and 4 deletions
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3
celt/arch.h
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@ -101,6 +101,9 @@ typedef opus_val32 celt_ener;
#define Q15ONE 32767 #define Q15ONE 32767
#define SIG_SHIFT 12 #define SIG_SHIFT 12
/* Safe saturation value for 32-bit signals. Should be less than
2^31*(1-0.85) to avoid blowing up on DC at deemphasis.*/
#define SIG_SAT (300000000)
#define NORM_SCALING 16384 #define NORM_SCALING 16384

8
celt/mdct.c
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@ -306,16 +306,16 @@ void clt_mdct_backward_c(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_sca
/* We swap real and imag because we're using an FFT instead of an IFFT. */ /* We swap real and imag because we're using an FFT instead of an IFFT. */
re = yp1[1]; re = yp1[1];
im = yp1[0]; im = yp1[0];
yp0[0] = yr; yp0[0] = SATURATE(yr, SIG_SAT);
yp1[1] = yi; yp1[1] = SATURATE(yi, SIG_SAT);
t0 = t[(N4-i-1)]; t0 = t[(N4-i-1)];
t1 = t[(N2-i-1)]; t1 = t[(N2-i-1)];
/* We'd scale up by 2 here, but instead it's done when mixing the windows */ /* We'd scale up by 2 here, but instead it's done when mixing the windows */
yr = ADD32_ovflw(S_MUL(re,t0), S_MUL(im,t1)); yr = ADD32_ovflw(S_MUL(re,t0), S_MUL(im,t1));
yi = SUB32_ovflw(S_MUL(re,t1), S_MUL(im,t0)); yi = SUB32_ovflw(S_MUL(re,t1), S_MUL(im,t0));
yp1[0] = yr; yp1[0] = SATURATE(yr, SIG_SAT);
yp0[1] = yi; yp0[1] = SATURATE(yi, SIG_SAT);
yp0 += 2; yp0 += 2;
yp1 -= 2; yp1 -= 2;
} }