Hello Natalia and Andreas,

Thank you for the replies and suggestions.  I will lookup V4L.  

Natalia,

So your patch creates a generic webcam under KVM/Qemu to allow many webcams to 
work?

My only concern is the following:   I use specific Philips webcams, and one in 
particular has a long exposure modification that the PWC driver (Fedora 11 
guest on Fedora 15 host) coupled with Qastrocam-G2 (v4.9) allows the "shutter" 
to remain open through USB control of the LED.  If the guest restorts to using 
a generic webcam driver, I think this would preclude functionality that the 
native driver supports ?  

Also, can you tell me - when KVM is running my guest, should the PWC webcam 
driver be loaded and/or the /dev/video0 on the HOST (F15), versus the guest 
(F11) ?   I am confused as to which components are supposed to be enabled or 
disabled while running the guest webcam.   What I see is when I enable the 
webcam USB device in KVM, it appears to disable the /dev/video0 on the host an 
brings it up in the guest.   And the pwc driver loads and remains on both host 
and guest.  

Peter


--- On Sun, 5/29/11, Natalia Portillo <clau...@claunia.com> wrote:

From: Natalia Portillo <clau...@claunia.com>
Subject: Re: [Qemu-devel] Webcams under KVM and Linux
To: "Andreas Färber" <andreas.faer...@web.de>
Cc: "Peter Baitz" <ussenterprisencc1...@rocketmail.com>, "QEMU Developers" 
<qemu-devel@nongnu.org>
Date: Sunday, May 29, 2011, 1:53 PM

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More concretely search for patches sent by me.

Even when EHCI is finished still is the problem of isochronous transfer not 
working well because of timing issues on QEMU.

My patches overcome the need for ISO transfer and EHCI controllers completely, 
as well as providing an universal device to the guest that works with every 
Windows >XP, every Linux and even Mac OS X.

El 29/05/2011, a las 14:37, Andreas Färber escribió:

> Hello,
> 
> Am 29.05.2011 um 15:01 schrieb Peter Baitz:
> 
>> 
>>> [...] You should notice that it is not just adding
>>> ISOC and USB 2.0 support, but also to prioritize the processing of isoc
>>> packets on a virtual environment, and to provide enough throughput for
>>> video streams
>> 
>> [...] Please check the qemu-devel mailing list archive, specifically 
>> regarding recent discussions about EHCI (USB 2.0). Some of those threads 
>> address isochronous transfer as well.
>> 
>> In the meantime, you could also try to assign a complete host controller to 
>> the guest to get a webcam working. I tried this a while ago, though the 
>> result was only moderately well working here.
> 
>> [...] I would indeed like to hear more about what the project is adding to 
>> KVM - Qemu to allow video to work with webcams
> [...]
>> I was told I could try to add a complete host controller to the guest, but 
>> am not entirely sure I understand what that means?  Looking for specifics?  
>> Is there a suggestion for doing this during install of the KVM guest, or can 
>> this be done while the guest is running, or otherwise?
> 
> Independent of the ongoing EHCI work, I remember a patch specifically for 
> webcams a while ago, try searching the archives for V4L.
> 
> Andreas

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