zipper noise with moving source and binaural effect about steam-audio HOT 4 OPEN

@grrrwaaa Do you encounter this issue when using IPL_HRTFINTERPOLATION_NEAREST? At first glance, things seem to be configured correctly in your code.

from steam-audio.

Hi there, thanks for looking at this.

Using IPL_HRTFINTERPOLATION_NEAREST doesn't make any difference as far as I can tell.

I've taken some screenshots of the waveforms I'm seeing, uploaded here:

https://www.dropbox.com/sh/023oy5r1a2swy1m/AADgDfkgN73X1QASZ1ZgqALea?dl=0

This was captured by panning a source signal that is a 2000Hz sinewave, panning around the listener a little faster than once per second. The sampling rate is 44.1kHz, IPL_HRTFINTERPOLATION_BILINEAR is enabled. Some are taken with a framesize of 64, some with a framesize of 1024 (indicated in the filename). OSX 64-bit.

In the most zoomed out picture there's very clearly linear stepping of the position, not interpolation. These artifacts seem to occur about every 2048 samples (regardless of my framesize -- I'm speculating that this is a function of the HRTF size so there's nothing I can do about it?) Still, in the most zoomed pictures at 64 framesize there's a very abrupt cut in both amplitude and phase, causing the crackle. In the zoomed in pictures at 1024 framesize, this manifests instead as a wobble over around 200ish samples -- presumably a crossfade between signals at different phases.

It's clear that there's going to be some kind of approximation for motion, since the direction vector is only updated as a step signal, at most once per framesize. But is there any way I can reduce the crackle? If the HRTFs are only updated every 2048 samples (which seems to be the case), then perhaps I can run two HRTFs in parallel and crossfade their outputs (perhaps interlaced, so that I can achieve a maximum rate of motion frequency of samplerate/1024)?

Graham

from steam-audio.

I've updated to the beta 10, and I still hear the zipper noise. It seems like the interpolation is now working correctly (with interpolation disabled I hear stepping as before). However even with interpolation enabled I am still seeing abrupt cuts with a frame size less than 2048 samples, leading to crackle. The lower the frame size, the more the crackle.

Is this library not intended to be used with frame sizes other than 2048 samples?

from steam-audio.

This issue has been automatically marked stale, and will automatically be closed in 30 days if no activity occurs.

from steam-audio.