webaudiofftperf

WebAudio FFT Performance Test

Aim

To have a simple repeatable test for looking at performance of JS FFT implementations run realtime within WebAudio using ScriptProcessorNode now, and AudioWorker node (when that's added) to compare and contrast against native implementation.

This fell out of the WebAudio Spec discussion

How?

Runs simple FFT passes over random data using either dsp.js, jsfft or fft-asm.js. (Please fork and add more)

The FFT size is settable, and so is the length of time the data is collected. The chunkSize for the ScriptProcessorNode is set to the same as FFT size.

The data collected is DOMHighResolutionTimeStamp at the following moments :

immediately at the beginning callback of the ScriptProcessorNode : onAudioProcessStart
before FFT calculation : onFFTStart
after FFT calculation : onFFTEnd
at the end of callback of the ScriptProcessorNode: onAudioProcessEnd

Using this data, the current graph plots :

the time difference between successive ScriptProcessorNode callbacks : (onAudioProcessStart[index]-onAudioProcessEnd[index-1]) - labelled as Callback (msec)
the time taken for the FFT : perf.onFFTEnd[index]-perf.onFFTStart[index] - labelled as FFTTime (msec)