Re: Sound error: Could not initialize DirectSoundCapture

[Peter Maydell]

On Mon, 7 Dec 2020 at 13:56, kazusanosuke_kaz
<kazusanosuke_kaz@yahoo.co.jp> wrote:
>
> Hi, all!
>
> I've just installed qemu to my PC, Windows 8.1(x64) with Core i5-4670 / MSI 
> MS-7817(OnBoard Sound) / GeForce GT 640
> Windows 98SE was successfully installed on qemu, but sound device doesn't 
> work ...
>
> "C:\Program Files\qemu\qemu-system-i386.exe" -device sb16 -m 512 
> Windows98SE.qcow2
> dsound: Could not initialize DirectSoundCapture
> dsound: Reason: No sound driver is available for use, or the given GUID is 
> not a valid DirectSound device ID

(I don't use Windows, but here are some suggestions based on
reading the source code.)

> Even though I choose another soundhw, the result is all the same

That's because this error message is not related to what sound
hardware is being given to the guest. It's the QEMU DirectSound
audio backend complaining that when it asked the host Windows
for a sound-input device (ie a microphone or similar) it got
an error back. (Specifically, the IDirectSoundCapture_Initialize()
call failed.) So the warnings are basically saying "sound input
to QEMU is not going to work", and they'll be printed for any
kind of sound hardware you give to the guest (sb16, ac97, ...).

That said, looking at the code I think that the DirectSound
backend attempts to continue even if audio input doesn't work.
So if you only care about audio output, in theory these warnings
should be harmless.

You could try some of the suggestions in this stack overflow
post:
https://stackoverflow.com/questions/55601413/how-to-fix-could-not-initialize-directsoundcapture-in-android-studio
(effectively "plug in a microphone" or "enable some windows-internal
input device") to see if they help. If that makes the warnings
go away and also makes sound output start working, then there
might be a bug in the QEMU code that is supposed to handle
"input doesn't work but proceed with output anyway". If the
warnings go away but sound output still doesn't work, then
the output problem is not related to the warnings.

thanks
-- PMM