SILK fixes following last codec WG meeting

decoder:
- fixed incorrect scaling of filter states for the smallest quantization
  step sizes
- NLSF2A now limits the prediction gain of LPC filters

encoder:
- increased damping of LTP coefficients in LTP analysis
- increased white noise fraction in noise shaping LPC analysis
- introduced maximum total prediction gain.  Used by Burg's method to
  exit early if prediction gain is exceeded.  This improves packet
  loss robustness and numerical robustness in Burg's method
- Prefiltered signal is now in int32 Q10 domain, from int16 Q0
- Increased max number of iterations in CBR gain control loop from 5 to 6
- Removed useless code from LTP scaling control
- Optimization: smarter LPC loop unrolling
- Switched default win32 compile mode to be floating-point

resampler:
- made resampler have constant delay of 0.75 ms; removed delay
  compensation from silk code.
- removed obsolete table entries (~850 Bytes)
- increased downsampling filter order from 16 to 18/24/36 (depending on
  frequency ratio)
- reoptimized filter coefficients

1 files changed, 4 insertions, 4 deletions

diff --git a/silk/NLSF2A.c b/silk/NLSF2A.c
index f2a26935..b10c6901 100644
--- a/silk/NLSF2A.c
+++ b/silk/NLSF2A.c
@@ -83,7 +83,7 @@ void silk_NLSF2A(
     opus_int32 P[ SILK_MAX_ORDER_LPC / 2 + 1 ], Q[ SILK_MAX_ORDER_LPC / 2 + 1 ];
     opus_int32 Ptmp, Qtmp, f_int, f_frac, cos_val, delta;
     opus_int32 a32_QA1[ SILK_MAX_ORDER_LPC ];
-    opus_int32 maxabs, absval, idx=0, sc_Q16, invGain_Q30;
+    opus_int32 maxabs, absval, idx=0, sc_Q16;
 
     silk_assert( LSF_COS_TAB_SZ_FIX == 128 );
     silk_assert( d==10||d==16 );
@@ -162,8 +162,8 @@ void silk_NLSF2A(
         }
     }
 
-    for( i = 1; i < MAX_LPC_STABILIZE_ITERATIONS; i++ ) {
-        if( silk_LPC_inverse_pred_gain( &invGain_Q30, a_Q12, d ) == 1 ) {
+    for( i = 1; i <= MAX_LPC_STABILIZE_ITERATIONS; i++ ) {
+        if( silk_LPC_inverse_pred_gain( a_Q12, d ) < SILK_FIX_CONST( 1.0 / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
             /* Prediction coefficients are (too close to) unstable; apply bandwidth expansion   */
             /* on the unscaled coefficients, convert to Q12 and measure again                   */
             silk_bwexpander_32( a32_QA1, d, 65536 - silk_SMULBB( 9 + i, i ) );            /* 10_Q16 = 0.00015 */
@@ -175,7 +175,7 @@ void silk_NLSF2A(
         }
     }
 
-    if( i == MAX_LPC_STABILIZE_ITERATIONS ) {
+    if( i > MAX_LPC_STABILIZE_ITERATIONS ) {
         /* Reached the last iteration, set coefficients to zero */
         for( k = 0; k < d; k++ ) {
             a_Q12[ k ] = 0;