Teensy 4 Audio Library with ASIO4ALL for Low-Latency Playback

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JayShoe

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Hello,

I'm testing my new DAC, and opened Ableton Live 10 Suite to see if I can use the DAC with it. I was hoping ASIO4ALL would work but I'm getting the following error.

abelton live teensy error.png

Live does not support 11025 as a sample rate for the device ASIO4ALL v2. I was searching forums for this problem and I came across the "ASIO4ALL Off-line Settings" and I know it's only the Teensy enabled.

ASIO4ALL teensy audio off-line settings.png

Has anyone else used Ableton Live with Teensy? With ASIO4ALL? Any advice would be appreciated.

Jay
 
How do you set up the USB audio-in endpoint? Are you using the audio library / setup?
I don't see code in the USB library to set up 11 kHz (it all sets up at 44 kHz) but maybe you changed something?
What DAC are you using, and how do you set that up?
 
Hello jwatte,

Sorry for the delayed response on this. I thought about your question.

How do you set up the USB audio-in endpoint? Are you using the audio library / setup?

This is a stock T4, with the USB Passthrough example running. File>Examples>Audio>PassThroughUSB. Sound comes through the DAC from the computer. ASIO requires a host application. So the ASIO4ALL is setup inside Live.

What DAC are you using, and how do you set that up?
I'm using my custom DAC, which is using I2S. In this example, I would assume (although I suppose not certain) that it doesn't matter. The DAC is just receiving the I2S data. I don't happen to have a PJRC audio shield currently for the T4.

I don't see code in the USB library to set up 11 kHz (it all sets up at 44 kHz) but maybe you changed something?

No I didn't change anything. At first I was wondering if the Teensy library didn't declare all the descriptors for the USB Audio spec. But then I found this, so it appears that the information is there. I wonder how I can view/test what's being seen by Windows in the descriptors?

Why would ASIO4ALL assume the T4 is running a sample rate of 11025??? There must be a way. Last night while jamming with friends I mistakenly and regretfully plugged a 12v supply into my 5v audio interface (Behringer) and broke it. At the same time I had a T4 and DAC sitting here and boy I wish this would work. It would be great to run the T4 as an audio recording interface.

Jay
 
So I just began to try out FlexASIO and good news - it works with the Teensy so far.

The latency is still a little too long for playing an instrument without lag... I'll continue testing different things to make it work.

I'm pretty sure the backend it's using is directshow. I'm pretty sure Teensy doesn't support WASAPI yet? Are there any plans for this? Here is a quote from the beta forum.

Results for type "Audio":
Works only for DirectSound. input output are functional.
Strange behavior in device manager: three endpoints listed under Audio inputs and outputs.
This even after USB oblivion or manual removal of all present and nonpresent entries of teensy.

Soundmapper works input and output, links to DirectSound.

Teensy reports to WASAPI as device, but no input or output channels available at no sample rate or format, no shared, no polled.
Looks like an error in the device descriptor.

WDM streaming fails.

ASIO non existent.

EDIT: when setting FlexASIO to WASAPI it does not work - "Failed to open audio device".
 
Hi PaulS,

Ahh yes! OK so I went crazy and uninstalled every sound device but the Teensy. Since I knew it CAN work, I tried that and it fixed it! There was some other device calling for the larger sample rate...

I wasn't even getting to the screen you see to select a samplerate. It was just the error.

OK, so I got it working on ASIO4ALL. Looks like I can get it down to 16.6 ms delay. Not bad. My instrument sounds ok so far. Would like to get it down to 11ms for sure. I'll experiment and report back. Thanks for your post. :)

Jay
 
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