Re: [Qemu-devel] Webcams under KVM and Linux

[Gerd Hoffmann <kraxel@redhat.com>]

On 05/30/11 14:50, Natalia Portillo wrote:
> Exactly what my webcam does is:
>
> Takes a frame from ANY available V4L2 device (/dev/video0), caches it,
> and sends it completely to the guest before requesting any other frame.

I think you can double-buffer (i.e. let the host driver fill one buffer 
while sending the other one to the guest).  Probably gives a slightly 
higher frame rate, but maybe at cost of added latencies.

> The guest sees a common USB Video Class Device webcam with no controls
> (this can be enhanced easily), so basically you cannot change any parameter.
> However all the webcams I tested automatically managed that in the
> firmware with no intervention from any of the drivers (host or guest),
> changing white balance and brightness to the adequate values.

Nice.  Patches are waiting for EHCI being merged I guess?

cheers,
   Gerd