shithub: opus

Info  •  Files  •  Log  •  Branches

Tighter bound in filter control in PLC

We can't use the attenuation since it doesn't apply to the memory

--- a/celt/celt_decoder.c

+++ b/celt/celt_decoder.c

@@ -641,13 +641,13 @@

 #ifdef FIXED_POINT

          /* For fixed-point, apply bandwidth expansion until we can guarantee that

             no overflow can happen in the IIR filter. This means:

-            attenuation*32768*sum(abs(filter)) < 2^31 */

+            32768*sum(abs(filter)) < 2^31 */

          while (1) {

             opus_val16 tmp=Q15ONE;

             opus_val32 sum=QCONST16(1., SIG_SHIFT);

             for (i=0;i<LPC_ORDER;i++)

                sum += ABS16(lpc[c*LPC_ORDER+i]);

-            if (MULT16_32_Q15(attenuation, sum) < 65535) break;

+            if (sum < 65535) break;

             for (i=0;i<LPC_ORDER;i++)

             {

                tmp = MULT16_16_Q15(QCONST16(.99f,15), tmp);