Merge pull request #1271 from sultanqasim/performance

performance: Improve resampler performance

resources/news.txt

@@ -26,6 +26,7 @@
   IMPROVED: Waterfall span setting is stored in milliseconds.
   IMPROVED: Added 6 dB attenuation to WAV file recordings to prevent clipping.
   IMPROVED: Use logarithmic scale for frequency zoom slider.
+  IMPROVED: Reduced CPU utilization of demodulators.
    CHANGED: Frequency zoom slider zooms around center of display.
    CHANGED: Disallow scrolling beyond the FFT frequency limits.
    CHANGED: Default narrow FM deviation increased to 5 kHz.

src/dsp/resampler_xx.cpp

@@ -25,6 +25,7 @@
 #include <gnuradio/filter/firdes.h>
 #include "dsp/resampler_xx.h"
 
+#define RESAMPLER_OUTPUT_MULTIPLE 4096
 
 /* Create a new instance of resampler_cc and return
  * a shared_ptr. This is effectively the public constructor.
@@ -57,6 +58,7 @@ resampler_cc::resampler_cc(float rate)
 
     /* create the filter */
     d_filter = gr::filter::pfb_arb_resampler_ccf::make(rate, d_taps, flt_size);
+    d_filter->set_output_multiple(RESAMPLER_OUTPUT_MULTIPLE);
 
     /* connect filter */
     connect(self(), 0, d_filter, 0);
@@ -82,6 +84,7 @@ void resampler_cc::set_rate(float rate)
     disconnect(d_filter, 0, self(), 0);
     d_filter.reset();
     d_filter = gr::filter::pfb_arb_resampler_ccf::make(rate, d_taps, flt_size);
+    d_filter->set_output_multiple(RESAMPLER_OUTPUT_MULTIPLE);
     connect(self(), 0, d_filter, 0);
     connect(d_filter, 0, self(), 0);
     unlock();