[xiph-cvs] cvs commit: vorbis/lib envelope.c iir.c iir.h

[Monty]

xiphmont    00/11/04 02:24:16

  Modified:    lib      Tag: branch_beta3 envelope.c iir.c iir.h
  Log:
  Clamp IIR highpass in envelope code to zero below a threshhold to
  avoid underflow.

Revision  Changes    Path
No                   revision

No                   revision

1.23.2.4  +2 -1      vorbis/lib/envelope.c

Index: envelope.c
===================================================================
RCS file: /usr/local/cvsroot/vorbis/lib/envelope.c,v
retrieving revision 1.23.2.3
retrieving revision 1.23.2.4
diff -u -r1.23.2.3 -r1.23.2.4
--- envelope.c	2000/11/04 06:43:49	1.23.2.3
+++ envelope.c	2000/11/04 10:24:15	1.23.2.4
@@ -12,7 +12,7 @@
  ********************************************************************
 
  function: PCM data envelope analysis and manipulation
- last mod: $Id: envelope.c,v 1.23.2.3 2000/11/04 06:43:49 xiphmont Exp $
+ last mod: $Id: envelope.c,v 1.23.2.4 2000/11/04 10:24:15 xiphmont Exp $
 
  Preecho calculation.
 
@@ -174,6 +174,7 @@
     float *filtered=ve->filtered[i];
     float *pcm=v->pcm[i];
     IIR_state *iir=ve->iir+i;
+    IIR_clamp(iir,9e-15);
     
     for(j=ve->current;j<v->pcm_current;j++)
       filtered[j]=IIR_filter(iir,pcm[j]);

1.2.2.3   +12 -3     vorbis/lib/iir.c

Index: iir.c
===================================================================
RCS file: /usr/local/cvsroot/vorbis/lib/iir.c,v
retrieving revision 1.2.2.2
retrieving revision 1.2.2.3
diff -u -r1.2.2.2 -r1.2.2.3
--- iir.c	2000/11/04 06:43:50	1.2.2.2
+++ iir.c	2000/11/04 10:24:15	1.2.2.3
@@ -12,7 +12,7 @@
  ********************************************************************
 
   function: Direct Form I, II IIR filters, plus some specializations
-  last mod: $Id: iir.c,v 1.2.2.2 2000/11/04 06:43:50 xiphmont Exp $
+  last mod: $Id: iir.c,v 1.2.2.3 2000/11/04 10:24:15 xiphmont Exp $
 
  ********************************************************************/
 
@@ -32,7 +32,6 @@
   s->coeff_A=_ogg_malloc(stages*sizeof(float));
   s->coeff_B=_ogg_malloc((stages+1)*sizeof(float));
   s->z_A=_ogg_calloc(stages*2,sizeof(float));
-  s->z_B=_ogg_calloc(stages*2,sizeof(float));
 
   memcpy(s->coeff_A,A,stages*sizeof(float));
   memcpy(s->coeff_B,B,(stages+1)*sizeof(float));
@@ -43,7 +42,6 @@
     free(s->coeff_A);
     free(s->coeff_B);
     free(s->z_A);
-    free(s->z_B);
     memset(s,0,sizeof(IIR_state));
   }
 }
@@ -65,6 +63,17 @@
   if(++s->ring>=stages)s->ring=0;
 
   return(newB);
+}
+
+/* prevents ringing down to underflow */
+void IIR_clamp(IIR_state *s,float thresh){
+  float *zA=s->z_A+s->ring;
+  int i;
+  for(i=0;i<s->stages;i++)
+    if(fabs(zA[i])>=thresh)break;
+  
+  if(i<s->stages)
+    memset(s->z_A,0,sizeof(float)*s->stages*2);
 }
 
 /* this assumes the symmetrical structure of the feed-forward stage of

1.2.2.2   +6 -6      vorbis/lib/iir.h

Index: iir.h
===================================================================
RCS file: /usr/local/cvsroot/vorbis/lib/iir.h,v
retrieving revision 1.2.2.1
retrieving revision 1.2.2.2
diff -u -r1.2.2.1 -r1.2.2.2
--- iir.h	2000/11/04 06:21:44	1.2.2.1
+++ iir.h	2000/11/04 10:24:15	1.2.2.2
@@ -12,7 +12,7 @@
  ********************************************************************
 
   function: Direct Form I, II IIR filters, plus some specializations
-  last mod: $Id: iir.h,v 1.2.2.1 2000/11/04 06:21:44 xiphmont Exp $
+  last mod: $Id: iir.h,v 1.2.2.2 2000/11/04 10:24:15 xiphmont Exp $
 
  ********************************************************************/
 
@@ -24,14 +24,14 @@
   float *coeff_A;
   float *coeff_B;
   float *z_A;
-  float *z_B;
   int ring;
   float gain;
 } IIR_state;
 
-void IIR_init(IIR_state *s,int stages,float gain, float *A, float *B);
-void IIR_clear(IIR_state *s);
-float IIR_filter(IIR_state *s,float in);
-float IIR_filter_ChebBand(IIR_state *s,float in);
+extern void IIR_init(IIR_state *s,int stages,float gain, float *A, float *B);
+extern void IIR_clear(IIR_state *s);
+extern float IIR_filter(IIR_state *s,float in);
+extern float IIR_filter_ChebBand(IIR_state *s,float in);
+extern void IIR_clamp(IIR_state *s,float thresh);
 
 #endif

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'cvs-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.