Tweak the SINC resampler parameters and double the performance. It's using about 10% CPU in the worse case now.
Change-Id: I50ac7e6c6702a427fa36ab6d976c507155057507
Signed-off-by: Glenn Kasten <gkasten@google.com>
diff --git a/tools/resampler_tools/fir.cpp b/tools/resampler_tools/fir.cpp
index f54c2cf..be33d54 100644
--- a/tools/resampler_tools/fir.cpp
+++ b/tools/resampler_tools/fir.cpp
@@ -62,10 +62,10 @@
// cut off frequency ratio Fc/Fs
// The bigger the stop-band, the less coefficients we'll need.
- double Fcr = 22050.0 / 48000.0;
+ double Fcr = 20000.0 / 48000.0;
// nzc is the number of zero-crossing on one half of the filter
- int nzc = 16;
+ int nzc = 8;
// alpha parameter of the kaiser window
// Larger numbers reduce ripples in the rejection band but increase
@@ -80,7 +80,7 @@
// 80 dB 7.865
// 90 dB 8.960
// 100 dB 10.056
- double alpha = 10.056; // -100dB stop-band attenuation
+ double alpha = 7.865; // -80dB stop-band attenuation
// 2^nz is the number coefficients per zero-crossing
// (int theory this should be 1<<(nc/2))