Distortions present when using audio interface of remote API

How to use Voicemeeter Remote API and control Voicemeeter Audio Engine
erik.vanhamme
Posts: 8
Joined: Tue Jan 17, 2017 11:46 am

Distortions present when using audio interface of remote API

Postby erik.vanhamme » Fri Sep 22, 2017 10:55 pm

I have these distortions both with my own small remote API client and with Equalizer APO.

If no remote is connected, the audio stream plays perfectly. Even when I do nothing in the plugin (just copy) I get the distortions.

I tested:
sample rates: 44.1kHz 48kHz and 96kHz
resolution: 16 and 24 bit
Devices: 1 WDM (asus xonar essence stx II), 2 ASIO (same asus and focusrite scarlett 18i20).

Using the normal voicemeeter, not the Banana.

64 Bit windows 10 pro.

What am I doing wrong?

erik.vanhamme
Posts: 8
Joined: Tue Jan 17, 2017 11:46 am

Re: Distortions present when using audio interface of remote API

Postby erik.vanhamme » Sat Sep 23, 2017 1:10 pm

It's the same on my secondary PC (Core i7 2600k, 8GB RAM).

Primary machine is: Core i7 6700k, 32GB RAM.

How can I attempt to debug this?

Vincent Burel
Site Admin
Posts: 579
Joined: Sun Jan 17, 2010 12:01 pm

Re: Distortions present when using audio interface of remote API

Postby Vincent Burel » Sun Sep 24, 2017 3:50 pm

Sounds like a problem of CPU load and/or too small buffering...
try with a buffering around 512 or 1024 sample on Voicemeeter Main Stream (output A1).

Then check your processing CPU load : must be below 80% real time.
any CPU load peak over 80%RT are expected to create a sound discontinuity.

erik.vanhamme
Posts: 8
Joined: Tue Jan 17, 2017 11:46 am

Re: Distortions present when using audio interface of remote API

Postby erik.vanhamme » Sun Sep 24, 2017 4:47 pm

Thanks for the response.

I just retested. CPU load is 2%. Buffer size is at 1024 samples. 24-bit 96kHz settings. I am configured for 8 channels. Voicemeeter outputs into ASIO device.

I even have the distortions when I plug in my own code which only copies input to output. I will continue to test, see if I can isolate the issue.

Vincent Burel
Site Admin
Posts: 579
Joined: Sun Jan 17, 2010 12:01 pm

Re: Distortions present when using audio interface of remote API

Postby Vincent Burel » Sun Sep 24, 2017 7:22 pm

strange... you should make the test with our gain Matrix example
(you can download the exe directly there: http://download.vb-audio.com/Download_C ... _v1000.zip
and if this example works ok, compare your code to this example...

erik.vanhamme
Posts: 8
Joined: Tue Jan 17, 2017 11:46 am

Re: Distortions present when using audio interface of remote API

Postby erik.vanhamme » Sun Sep 24, 2017 10:11 pm

I was able to get the distortions also with the 8x8 matrix example. I got into that situation 2 times in half an hour of reboots and tests.

The problem does not occur all the time. With equalizer APO it occurs 50-60% of the time. For the 8x8 matrix, it happens much much less, but it did happen twice.

The problems occur more on my fastest PC. I have seen it only occasionally on my 2600k machine, and never on my laptop.

It smells like a race condition in the initialization of the VMR_APO.

Is there a log or debug tracer I can enable in VoiceMeeter to do more tests?

It's hard to describe the distortions, but I noticed that the sound with distortions is always quieter then without the VMR_APO active. (If I kill the APO process, the volume increases) It's like there are a bunch of 0's in the buffers. I will try to make a VMR APO that dumps the input data to disk to see what gets passed into the APO.

erik.vanhamme
Posts: 8
Joined: Tue Jan 17, 2017 11:46 am

Re: Distortions present when using audio interface of remote API

Postby erik.vanhamme » Sun Sep 24, 2017 10:48 pm

The plot thickens...

I have made recordings with Audacity of the distortions. To obtain the recordings, I linked the virtual input to strip B, and recorded from voicemeeter output in Audacity.

First recording is the start of a DnB liveset:
http://users.telenet.be/rsq/distortions.wav

From the waveform I could not tell what was going on, no zeroes as I thought.

To get a clearer picture, I generated a 440Hz sine wave in audacity and played it back, again recording the distortions. There are clear phasing errors apparent in the waveform.
http://users.telenet.be/rsq/distorted_sine.wav

These distortions were made with the vmr_matrix.exe you linked to earlier.

If there are more tests I can do, please let me know.

Vincent Burel
Site Admin
Posts: 579
Joined: Sun Jan 17, 2010 12:01 pm

Re: Distortions present when using audio interface of remote API

Postby Vincent Burel » Mon Sep 25, 2017 8:07 am

your sound shows clearly a discontinuity problem (due to timing issue in audio buffering process somewhere).

i've just made the test with Voicemeeter 1.0.5.5 / 2.0.3.5 on WIN7 32 & 64 bits
and i got no problem with the Gain Matrix Example.
Also made the test on WIN10 x64 family (96kz / 1024 smp).

So, i cannot reproduce the problem here. The only problem i saw is that GAIN MATRIX must be launched after having configuring Voicemeeter, to be sure that it will work ok, because sometimes the client audio app stop working after having changed the samplerate in Voicemeeter System Settings... will be corrected later.

So, your problem is maybe more located on the Voicemeeter Main Stream ... given by the audio device selected as output A1
this stream must work ok, if this stream (usually used for monitoring) is not working, nothing else could not work correct.

if you need more help, you may send a screenshot of Voicemeeter System Settings Dialog Box to let me see your configuration.


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