ref: fbfddf70412897fce824940806b5580a0082fe19
parent: 692c33f8bb36ed9e1fd34c852899de82be815b85
author: Jean-Marc Valin <[email protected]>
date: Sun Jul 19 17:07:12 EDT 2009
Making sure each band has a width that's a multiple of the number of MDCTs
--- a/libcelt/modes.c
+++ b/libcelt/modes.c
@@ -84,12 +84,6 @@
#define PBANDS 8
-#ifdef STDIN_TUNING
-int MIN_BINS;
-#else
-#define MIN_BINS 3
-#endif
-
/* Defining 25 critical bands for the full 0-20 kHz audio bandwidth
Taken from http://ccrma.stanford.edu/~jos/bbt/Bark_Frequency_Scale.html */
#define BARK_BANDS 25
@@ -128,12 +122,16 @@
};
#endif
-static celt_int16_t *compute_ebands(celt_int32_t Fs, int frame_size, int *nbEBands)
+static celt_int16_t *compute_ebands(celt_int32_t Fs, int frame_size, int nbShortMdcts, int *nbEBands)
{+ int min_bins = 2;
celt_int16_t *eBands;
int i, res, min_width, lin, low, high, nBark;
+
+ if (min_bins < nbShortMdcts)
+ min_bins = nbShortMdcts;
res = (Fs+frame_size)/(2*frame_size);
- min_width = MIN_BINS*res;
+ min_width = min_bins*res;
/* Find the number of critical bands supported by our sampling rate */
for (nBark=1;nBark<BARK_BANDS;nBark++)
@@ -145,7 +143,7 @@
if (bark_freq[lin+1]-bark_freq[lin] >= min_width)
break;
- low = ((bark_freq[lin]/res)+(MIN_BINS-1))/MIN_BINS;
+ low = ((bark_freq[lin]/res)+(min_bins-1))/min_bins;
high = nBark-lin;
*nbEBands = low+high;
eBands = celt_alloc(sizeof(celt_int16_t)*(*nbEBands+2));
@@ -155,19 +153,28 @@
/* Linear spacing (min_width) */
for (i=0;i<low;i++)
- eBands[i] = MIN_BINS*i;
+ eBands[i] = min_bins*i;
/* Spacing follows critical bands */
for (i=0;i<high;i++)
- eBands[i+low] = (bark_freq[lin+i]+res/2)/res;
+ eBands[i+low] = (bark_freq[lin+i]+res/2)/res/nbShortMdcts*nbShortMdcts;
/* Enforce the minimum spacing at the boundary */
for (i=0;i<*nbEBands;i++)
- if (eBands[i] < MIN_BINS*i)
- eBands[i] = MIN_BINS*i;
- eBands[*nbEBands] = (bark_freq[nBark]+res/2)/res;
+ if (eBands[i] < min_bins*i)
+ eBands[i] = min_bins*i;
+ eBands[*nbEBands] = (bark_freq[nBark]+res/2)/res/nbShortMdcts*nbShortMdcts;
eBands[*nbEBands+1] = frame_size;
if (eBands[*nbEBands] > eBands[*nbEBands+1])
eBands[*nbEBands] = eBands[*nbEBands+1];
-
+ for (i=1;i<*nbEBands-1;i++)
+ {+ if (eBands[i+1]-eBands[i] < eBands[i]-eBands[i-1])
+ {+ eBands[i] -= min_bins;
+ }
+ }
+ /*for (i=0;i<*nbEBands+1;i++)
+ printf ("%d ", eBands[i]);+ printf ("\n");*//* FIXME: Remove last band if too small */
return eBands;
}
@@ -344,12 +351,6 @@
mode->Fs = Fs;
mode->mdctSize = frame_size;
mode->nbChannels = channels;
- mode->eBands = compute_ebands(Fs, frame_size, &mode->nbEBands);
- if (mode->eBands==NULL)
- goto failure;
- compute_pbands(mode, res);
- if (mode->pBands==NULL)
- goto failure;
mode->ePredCoef = QCONST16(.8f,15);
if (frame_size > 640 && (frame_size%16)==0)
@@ -377,6 +378,13 @@
{mode->nbShortMdcts = 1;
}
+
+ mode->eBands = compute_ebands(Fs, frame_size, mode->nbShortMdcts, &mode->nbEBands);
+ if (mode->eBands==NULL)
+ goto failure;
+ compute_pbands(mode, res);
+ if (mode->pBands==NULL)
+ goto failure;
/* Overlap must be divisible by 4 */
if (mode->nbShortMdcts > 1)