No audio with ubuntu(virtual machine)

[gmikitiuk]

Hi,

I've successfully got audio working on Windows without any issues but it doesn't work with ubuntu at all.
Slightly modified uac2_headset example. 2 channels, 16bit, 48000kHz.

What I've found so far:

• It is detected as audio device on ubuntu aplay --list-device.
• Cannot play any system sounds, nor from the 3rd party apps like Audacity.
• Alternate interface for streaming is selected.
• No audio packets are sent(?), not reaching audiod_xfer_cb at all.
• It works with my other USB audio devices, so it's not VM/ubuntu issue most likely itself.

Is there anything I should know about audio with linux? Are there any special requirements(ie. on descriptor, endpoint sizes)?

[gmikitiuk]

Also no DCD_EVENT_XFER_COMPLETE at all

usbtop on ubuntu shows the expected traffic to the usb device.

I'm a little bit confused where the audio is getting lost...

[HiFiPhile]

Hum... anything in dmesg ?

The only issue I know is with composite device of multiples UAC instances, where entityID of different instances should be unique, but it doesn't applicable for uac2_headset since it has only one UAC instance.

https://github.com/hathach/tinyusb/blame/6bba41045a4224abb68256dcf2fce893da47a743/examples/device/uac2_headset/src/usb_descriptors.h#L32

[gmikitiuk]

Nothing unusual in dmesg, no errors from the usb device at all.

[gmikitiuk]

@HiFiPhile I've just tested with another machine which do have ubuntu(to exclude VM issues) and the audio is working as expected.
Now I think that it's the VM to blame, according to usbtop there is audio traffic ongoing, so it must be getting lost somewhere further.

[HiFiPhile]

Interesting, maybe USB passthrough doesn't work well with ISO transfer. Do you use Qemu KVM or something else ?

[gmikitiuk]

I do use virtualbox.
I've now changed to USB 3.0 xHCI Controller and at least transfers are going but they're way too slow which leads to multiple underruns on the device itself. This still needs investigation if any improvement is possible.