shithub: opus

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Fix potential overflow in IMDCT headroom

--- a/celt/mdct.c

+++ b/celt/mdct.c

@@ -292,11 +292,11 @@

       opus_val32 maxval=0;

       for (i=0;i<N2;i++) {

          maxval = MAX32(maxval, ABS32(in[i*stride]));

-         sumval = ADD32_ovflw(sumval, ABS32(SHR32(in[i*stride],4)));

+         sumval = ADD32_ovflw(sumval, ABS32(SHR32(in[i*stride],11)));

       }

       pre_shift = IMAX(0, 29-celt_ilog2(1+SHR32(maxval,2)*3));

       /* Worst-case where all the energy goes to a single sample. */

-      post_shift = IMAX(0, 26-celt_ilog2(ABS32(sumval)));

+      post_shift = IMAX(0, 19-celt_ilog2(ABS32(sumval)));

       post_shift = IMIN(post_shift, pre_shift);

       fft_shift = pre_shift - post_shift;

    }

-- 

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