From: drowe67 <drowe67@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Fri, 9 Oct 2009 01:45:26 +0000 (+0000)
Subject: added an explicit voicing decn flag
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=cd790b312218db1432f0822693b0a4da9b8651cb;p=freetel-svn-tracking.git

added an explicit voicing decn flag

git-svn-id: https://svn.code.sf.net/p/freetel/code@73 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/codec2/src/phase.c b/codec2/src/phase.c
index 2fdef26b..8f695411 100644
--- a/codec2/src/phase.c
+++ b/codec2/src/phase.c
@@ -32,8 +32,7 @@
 #include <assert.h>
 #include <string.h>
 
-#define VTHRESH1 2.0
-#define VTHRESH2 2.0
+#define VTHRESH 2.0
 
 /*---------------------------------------------------------------------------*\
 
@@ -129,7 +128,8 @@ float phase_model_first_order(
   float  aks[],                  /* LPC coeffs for this frame      */
   COMP   H[],		         /* LPC filter freq doamin samples */
   float *n_min,                  /* pulse position for min error   */ 
-  COMP  *minAm                   /* complex gain for min error     */
+  COMP  *minAm,                  /* complex gain for min error     */
+  int   *voiced
 ) 
 {
   float G;			/* LPC gain */
@@ -217,6 +217,10 @@ float phase_model_first_order(
   }
 
   snr = 10.0*log10(sig/Emin);
+  if (snr > VTHRESH)
+      *voiced = 1;
+  else
+      *voiced = 0;
 
   return snr;
 }
@@ -297,35 +301,15 @@ float phase_model_first_order(
 void phase_synth_zero_order(
   float  snr,     /* SNR from first order model                */
   COMP   H[],     /* LPC spectra samples                       */
-  float *ex_phase /* excitation phase of fundamental           */
+  float *ex_phase,/* excitation phase of fundamental           */
+  int    voiced
 )
 {
-  int   Lrand;
   int   m;
   float new_phi;
   COMP  Ex[MAX_AMP];		/* excitation samples */
   COMP  A_[MAX_AMP];		/* synthesised harmonic samples */
 
-  /* 
-     Bunch of mixed voicing thresholds tried but in the end a simple
-     voiced/unvoiced model worked best.  With mixed voicing some
-     unvoiced speech had a "clicky" sound due to occasional high SNR
-     causing the first few harmonics to be modelled as voiced. I don't
-     really understand why simple one bit V/UV sounds so good -
-     everyone else seems to think mixed voicing models are required
-     for good quality speech.
-
-     Note code below supports mixed voicing but with VTHRESH1 == VTHRESH2
-     we get a simple V/UV model.
-  */
-
-  Lrand = model.L;
-  if (snr < VTHRESH2) {
-    Lrand = floor(model.L*(snr-VTHRESH1)/(VTHRESH2-VTHRESH1));
-    if (Lrand < 1) Lrand = 0;
-    if (Lrand > model.L) Lrand = model.L;
-  }
-
   /* 
      Update excitation fundamental phase track, this sets the position
      of each pitch pulse during voiced speech.  After much experiment
@@ -344,7 +328,7 @@ void phase_synth_zero_order(
 
     /* generate excitation */
 
-    if (m <= Lrand) {
+    if (voiced) {
 	Ex[m].real = cos(ex_phase[0]*m);
         Ex[m].imag = sin(ex_phase[0]*m);
 
@@ -405,7 +389,8 @@ void phase_synth_first_order(
   float snr,     /* SNR from first order model */
   COMP  H[],     /* LPC spectra samples        */
   float n_min,   /* best pulse position        */
-  COMP  minAm    /* best complex gain          */
+  COMP  minAm,   /* best complex gain          */
+  int   voiced
 )
 {
   int   Lrand;
@@ -415,22 +400,13 @@ void phase_synth_first_order(
   COMP  A_[MAX_AMP];		/* synthesised harmonic samples */
   COMP  Tm;  			
 
-  /* see notes in zero phase function above to V/UV model */
-
-  Lrand = model.L;
-  if (snr < VTHRESH2) {
-    Lrand = floor(model.L*(snr-VTHRESH1)/(VTHRESH2-VTHRESH1));
-    if (Lrand < 1) Lrand = 1;
-    if (Lrand > model.L) Lrand = model.L;
-  }
-
   /* now modify sinusoidal model phase using phase model */
 
   for(m=1; m<=model.L; m++) {
 
     /* generate excitation */
 
-    if (m <= Lrand) {
+    if (voiced) {
 	Ex[m].real = cos(model.Wo*m*n_min);
 	Ex[m].imag = sin(-model.Wo*m*n_min);
     }
diff --git a/codec2/src/phase.h b/codec2/src/phase.h
index 996ed3fc..e6b4e8c3 100644
--- a/codec2/src/phase.h
+++ b/codec2/src/phase.h
@@ -32,8 +32,10 @@
 #define PHASE_LPC_ORD 10
 
 void aks_to_H(MODEL *model, float aks[], float G, COMP H[], int order);
-float phase_model_first_order(float aks[], COMP H[], float *n_min, COMP *min_Am);
-void phase_synth_zero_order(float snr, COMP H[], float *ex_phase);
-void phase_synth_first_order(float snr, COMP H[], float n_min, COMP min_Am);
+float phase_model_first_order(float aks[], COMP H[], float *n_min, COMP *min_Am,
+			      int *voiced);
+void phase_synth_zero_order(float snr, COMP H[], float *ex_phase, int voiced);
+void phase_synth_first_order(float snr, COMP H[], float n_min, COMP min_Am, 
+			     int voiced);
 
 #endif