Cannot use microphone. Applications that try to record audio hang

[abacabadabacaba]

After I upgraded VirtualBox from 5.x to 6.0.4, I can no longer use microphone from within the VirtualBox VM. I run Debian on both the host and the guest system.

Steps to reproduce:

• Create a new VM. Set guest OS to Debian 64-bit, don't change any other settings.
• Boot the VM using a Debian live CD.
• Enable audio input for the VM.
• Inside the VM, try to use a program that tries to record audio, such as SOX (run these commands: apt-get install sox; rec -n).
• Observe that the program hangs. On the host system, the same program works fine.

[Socratis]

It's usually better and faster, if issues get first addressed in the ​VirtualBox forums, a lot more eyes there. More than 95% of the issues are resolved in the forums, which keeps the developers focusing on the bug fixes and enhancements, and there is no need for another ticket to keep track of. For example, yours is most probably not a bug and someone from the developers has to deal with it and close it as "Invalid".

Plus a discussion and analysis on the bug tracker is going to help you, me, and potentially a future drive-by user or two. Not so in the forums, many more tend to benefit...

00:00:11.389600 VirtualBox VM 6.0.4_Debian r128164 linux.amd64 (Jan 31 2019 14:42:02) release log

It looks like you're using the Debian fork version of VirtualBox. You can either ask in their forums/channels for help, or completely remove/uninstall/delete/purge their version and install the official version from the Linux Downloads section of VirtualBox.

00:00:11.510345 File system of '/path/to/vm/test/test.vdi' is ext4

Please do not obfuscate the information requested. You may have a path with non-ASCII characters and that may turn out to be a bug in itself. "​Stasi" has closed shop, there's not that much to worry about... ;)

00:00:11.573375   Driver <string>  = "ALSAAudio" (cb=10)

Tried anything else, like Pulse?

I tested a clean Debian 9.5 installation on an OSX host. I went to the Debian System Preferences and I could clearly see the microphone input reading changing while I was speaking in the microphone. Did you try something as simple as the basic tests to see if the microphone is working? Or did you go straight to the app?

I then installed "sox", and run "rec -n". I'm not familiar with that program, so I don't know what I should be seeing, but here's what I did see:

$ rec -n

Input File     : 'default' (alsa)
Channels       : 2
Sample Rate    : 48000
Precision      : 16-bit
Sample Encoding: 16-bit Signed Integer PCM

In:0.00% 00:00:14.76 [00:00:00.00] Out:705k  [   -==|==-   ]        Clip:0    ^C
Aborted.

With the "[ -==|==- ]" part dynamically reflecting the audio input level.

[phaoost]

I have the same issue with ALSA driver on 6.1.6r137129

[phaoost]

vbox log from 6.1.6r137129