Decimation

h1. Summary of results

We compared

* @decimate@: the "Decimator"http://code.soundsoftware.ac.uk/projects/qm-dsp/embedded/classDecimator.html implementation in the "qm-dsp":/projects/qm-dsp library, which uses an 8-tap IIR lowpass filter;

* @resample_hq@, @resample_mq@, @resample_lq@: the "Resampler":http://code.soundsoftware.ac.uk/projects/qm-dsp/embedded/classResampler.html implementation in the "qm-dsp":/projects/qm-dsp library, which uses a lengthy Kaiser-windowed sinc filter, at three different quality settings;

* @src@: the sndfile-resample program which uses "libsamplerate":http://mega-nerd.com/SRC/, a well trusted resampler also using a Kaiser-windowed sinc implementation, at its default quality setting;

* @zoh@: the sndfile-resample zero-order hold resampler, which just takes every Nth sample without any filtering, serving as a baseline.

h2. Speed

h3. Implementations by decimation factor

For 5292000 input frames.

h4. Factor 2

|Frames per second|Clock time|Implementation|
| 14225806|0.372|decimate|
| 8939189|0.592|zoh|
| 3732016|1.418|resample_lq|
| 1856842|2.850|resample_mq|
| 989158|5.350|resample_hq|
| 516141|10.253|src|

h4. Factor 4
h4. Factor 8
h4. Factor 16
h4. Factor 32
h4. Factor 64