Adds an NSQ offset as a last resort to avoid busting with CBR.

5 files changed, 33 insertions, 0 deletions

diff --git a/silk/NSQ.c b/silk/NSQ.c
index a0658840..39f35bd8 100644
--- a/silk/NSQ.c
+++ b/silk/NSQ.c
@@ -310,6 +310,15 @@ void silk_noise_shape_quantizer(
 
         /* Find two quantization level candidates and measure their rate-distortion */
         q1_Q10 = silk_SUB32( r_Q10, offset_Q10 );
+        if (NSQ->res_offset) {
+            if (q1_Q10 > NSQ->res_offset) {
+                q1_Q10 -= NSQ->res_offset;
+            } else if (q1_Q10 < -NSQ->res_offset) {
+                q1_Q10 += NSQ->res_offset;
+            } else {
+                q1_Q10 = 0;
+            }
+        }
         q1_Q0 = silk_RSHIFT( q1_Q10, 10 );
         if( q1_Q0 > 0 ) {
             q1_Q10  = silk_SUB32( silk_LSHIFT( q1_Q0, 10 ), QUANT_LEVEL_ADJUST_Q10 );
diff --git a/silk/NSQ_del_dec.c b/silk/NSQ_del_dec.c
index aff560c2..bfbd8f67 100644
--- a/silk/NSQ_del_dec.c
+++ b/silk/NSQ_del_dec.c
@@ -469,6 +469,15 @@ static OPUS_INLINE void silk_noise_shape_quantizer_del_dec(
 
             /* Find two quantization level candidates and measure their rate-distortion */
             q1_Q10 = silk_SUB32( r_Q10, offset_Q10 );
+            if (NSQ->res_offset) {
+                if (q1_Q10 > NSQ->res_offset) {
+                    q1_Q10 -= NSQ->res_offset;
+                } else if (q1_Q10 < -NSQ->res_offset) {
+                    q1_Q10 += NSQ->res_offset;
+                } else {
+                    q1_Q10 = 0;
+                }
+            }
             q1_Q0 = silk_RSHIFT( q1_Q10, 10 );
             if( q1_Q0 > 0 ) {
                 q1_Q10  = silk_SUB32( silk_LSHIFT( q1_Q0, 10 ), QUANT_LEVEL_ADJUST_Q10 );
diff --git a/silk/fixed/encode_frame_FIX.c b/silk/fixed/encode_frame_FIX.c
index 5ef44b03..4d2d3fcb 100644
--- a/silk/fixed/encode_frame_FIX.c
+++ b/silk/fixed/encode_frame_FIX.c
@@ -118,6 +118,7 @@ opus_int silk_encode_frame_FIX(
     silk_memcpy( x_frame + LA_SHAPE_MS * psEnc->sCmn.fs_kHz, psEnc->sCmn.inputBuf + 1, psEnc->sCmn.frame_length * sizeof( opus_int16 ) );
 
     if( !psEnc->sCmn.prefillFlag ) {
+        int res_offset = 0;
         VARDECL( opus_int32, xfw_Q3 );
         VARDECL( opus_int16, res_pitch );
         VARDECL( opus_uint8, ec_buf_copy );
@@ -193,6 +194,7 @@ opus_int silk_encode_frame_FIX(
                 /*****************************************/
                 /* Noise shaping quantization            */
                 /*****************************************/
+                psEnc->sCmn.sNSQ.res_offset = res_offset;
                 if( psEnc->sCmn.nStatesDelayedDecision > 1 || psEnc->sCmn.warping_Q16 > 0 ) {
                     silk_NSQ_del_dec( &psEnc->sCmn, &psEnc->sCmn.sNSQ, &psEnc->sCmn.indices, xfw_Q3, psEnc->sCmn.pulses,
                            sEncCtrl.PredCoef_Q12[ 0 ], sEncCtrl.LTPCoef_Q14, sEncCtrl.AR2_Q13, sEncCtrl.HarmShapeGain_Q14,
@@ -239,6 +241,11 @@ opus_int silk_encode_frame_FIX(
                 if( found_lower == 0 && iter >= 2 ) {
                     /* Adjust the quantizer's rate/distortion tradeoff and discard previous "upper" results */
                     sEncCtrl.Lambda_Q10 = silk_ADD_RSHIFT32( sEncCtrl.Lambda_Q10, sEncCtrl.Lambda_Q10, 1 );
+                    if (res_offset) {
+                        res_offset *= 2;
+                    } else {
+                        res_offset = 512;
+                    }
                     found_upper = 0;
                     gainsID_upper = -1;
                 } else {
diff --git a/silk/float/encode_frame_FLP.c b/silk/float/encode_frame_FLP.c
index 2092a4d9..e1e19e5e 100644
--- a/silk/float/encode_frame_FLP.c
+++ b/silk/float/encode_frame_FLP.c
@@ -126,6 +126,7 @@ opus_int silk_encode_frame_FLP(
     }
 
     if( !psEnc->sCmn.prefillFlag ) {
+        int res_offset = 0;
         /*****************************************/
         /* Find pitch lags, initial LPC analysis */
         /*****************************************/
@@ -188,6 +189,7 @@ opus_int silk_encode_frame_FLP(
                 /*****************************************/
                 /* Noise shaping quantization            */
                 /*****************************************/
+                psEnc->sCmn.sNSQ.res_offset = res_offset;
                 silk_NSQ_wrapper_FLP( psEnc, &sEncCtrl, &psEnc->sCmn.indices, &psEnc->sCmn.sNSQ, psEnc->sCmn.pulses, xfw );
 
                 /****************************************/
@@ -224,6 +226,11 @@ opus_int silk_encode_frame_FLP(
                 if( found_lower == 0 && iter >= 2 ) {
                     /* Adjust the quantizer's rate/distortion tradeoff and discard previous "upper" results */
                     sEncCtrl.Lambda *= 1.5f;
+                    if (res_offset) {
+                        res_offset *= 2;
+                    } else {
+                        res_offset = 512;
+                    }
                     found_upper = 0;
                     gainsID_upper = -1;
                 } else {
diff --git a/silk/structs.h b/silk/structs.h
index 827829dc..66c63d6b 100644
--- a/silk/structs.h
+++ b/silk/structs.h
@@ -54,6 +54,7 @@ typedef struct {
     opus_int32                  rand_seed;
     opus_int32                  prev_gain_Q16;
     opus_int                    rewhite_flag;
+    opus_int16                  res_offset;
 } silk_nsq_state;
 
 /********************************/