[#1350] Set defaults for scaling in the event of an all-zero input vector, or all zero power spectrum.

git-svn-id: https://gforge.ti.com/svn/tiesr/trunk@74 469fd053-429d-4955-9e4c-93c0d7a8ff27

2 files changed, 34 insertions, 33 deletions

diff --git a/TIesrEngine/src/dist.cpp b/TIesrEngine/src/dist.cpp
index 024d467..587ab88 100755
--- a/TIesrEngine/src/dist.cpp
+++ b/TIesrEngine/src/dist.cpp
@@ -510,10 +510,11 @@ log_polyfit(long value, short compensate)
      Here we treat 2^30 as 0.5, so we need to compensate 31,
      31 - norm -compensate */
   tmp >>= 6;                                          /* Q 25 */
+  tmp += 1040187392;                                  /* 31 in Q 25 */
   tmp -= (long) norm << 25;                           /* log norm */
   tmp -= (long) compensate << 25;
 
-  tmp += 1040187392;                                  /* 31 in Q 25 */
+
 
   result =  LONG_RIGHT_SHIFT_N( tmp , 16 );        /* Q 25 - 16 = Q 9 */
 
diff --git a/TIesrEngine/src/mfcc_f.cpp b/TIesrEngine/src/mfcc_f.cpp
index 7d22a72..08f4ad7 100755
--- a/TIesrEngine/src/mfcc_f.cpp
+++ b/TIesrEngine/src/mfcc_f.cpp
@@ -572,12 +572,15 @@ ss_power_spectrum_to_mfcc(const short *power_spectrum,
   /* mel_energy : Q24 */
   
   /* log cannot handle 0, so substitute with min / 2 */
-  tmp = 2147483647;    /* LONG_MAX */
+  tmp = LONG_MAX;    /* LONG_MAX */
   for (i = 0; i < n_filter; i++)
     if ( mel_energy[ i ] != 0 && mel_energy[ i ] < tmp ) 
       tmp = mel_energy[ i ];
 
-  tmp = tmp >= 2 ? ( tmp >> 1 ) : tmp;
+  if( tmp == LONG_MAX )
+    tmp = 0;
+
+  tmp = tmp >= 2 ? ( tmp >> 1 ) : 1;
 
   for (i = 0; i < n_filter; i++)
     if ( mel_energy[ i ] == 0 ) mel_energy[ i ] = tmp;    
@@ -699,12 +702,15 @@ fft_spectrum_to_mfcc(const short *real_sig,const short *imag_sig,
   mel_scale_fft_spectrum(real_sig, imag_sig, mel_energy, n_filter, mel_filter);
   /* mel_energy is Q24 */
   /* log cannot handle 0, so substitute with min / 2 */
-  min = 2147483647;    /* LONG_MAX */
+  min = LONG_MAX;    /* LONG_MAX */
   for (i = 0; i < n_filter; i++)
     if ( mel_energy[ i ] != 0 && mel_energy[ i ] < min ) 
       min = mel_energy[ i ];
 
-  min = min >= 2 ? ( min >> 1 ) : min;
+  if( min == LONG_MAX )
+    min = 0;
+
+  min = min >= 2 ? ( min >> 1 ) : 1;
 
   for (i = 0; i < n_filter; i++)
     if ( mel_energy[ i ] == 0 ) mel_energy[ i ] = min;    
@@ -891,30 +897,25 @@ static short hamming_window(short *sig)
   short i;
   long  tmp, max;
   short norm1;
-  max = 0;
 
-  /* find max */
+  /* For scaling in case input sig is all zeros, set max
+   to minimum value it could have if any sig were non-zero. */
+  max = (1<<13) * hw[0];
 
+  /* find max */
   for (i = 0; i < WINDOW_LEN; i++) {
     tmp = sig[i] * hw[i];             /* Q 15 * Q 15 = Q 30 */
     tmp = tmp > 0 ? tmp : (- tmp);
     if ( tmp > max ) max = tmp;
   }
 
-  /* normalize to most precision */
-
-  if ( max > 0 ) {
-
-    for (norm1 = 0; max < 0x40000000; norm1++)
-      max <<= 1;
+   /* normalize to most precision */
+  for (norm1 = 0; max < 0x40000000; norm1++)
+    max <<= 1;
     
-    norm1 = norm1 > 0 ? norm1 - 1 : norm1;
-
-  } else {
-
-    norm1 = 0;
-  }
+  norm1 = norm1 > 0 ? norm1 - 1 : norm1;
 
+  
   /* Hamming window */
 
   for (i = 0; i < WINDOW_LEN; i++) {
@@ -954,9 +955,11 @@ static short preemphasis(short *sig_in, short *sig_out, short *last_sig_0)
     
     norm0 = norm0 > 0 ? norm0 - 1 : norm0;
 
-  } else {
-
-    norm0 = 0;
+  } 
+  else 
+  {
+    /* If sig_in is all zeros, set normalization factor as if max=1*/
+    norm0 = 13;
   }
 
   tmp1 = (last_sig << norm0) * PREEMPHASIS;          /* Q 15 * Q 15 = Q 30 */
@@ -983,10 +986,14 @@ static short fft_to_power_spectrum(const short *real, const short *imag, short *
   short i, norm2;
   long  tmp, max;
 
-  max = 0;
+   /* For scaling in case input signal is all zeros resulting in all zero
+   fft coefficients, set max to minimum value squared fft magnitude
+   could have if any signal input were non-zero. */
+  max = 20968 >> WINDOW_PWR;
+  max = 2*max*max;
 
   /* find max */
-  
+
   for (i = 0; i < WINDOW_LEN >> 1; i++) {
     tmp = real[i] * real[i] + imag[i] * imag[i];
     tmp <<= 1; /* Times 2 */
@@ -995,15 +1002,8 @@ static short fft_to_power_spectrum(const short *real, const short *imag, short *
 
   /* normalize to most precision */
 
-  if ( max > 0 ) {
-
-    for (norm2 = 0; max < 0x40000000; norm2++)
-      max <<= 1;
-
-  } else { /* max == 0 */
-
-    norm2 = 2;
-  }
+  for (norm2 = 0; max < 0x40000000; norm2++)
+    max <<= 1;
 
 
   //  assert( ( norm2 - 2 ) < 0);