[Qemu-devel] Re: Webcam solution for QEMU

[Qemu-devel] Re: Webcam solution for QEMU

[Arnon Gilboa]

Hello Albert,

First of all, I have done nothing in the qemu project for more than two 
years now. My last contribution to qemu were some usb 1.1 uhci/ohci 
patches for very basic support of webcams and other isochronous devices 
(accepted), and a preliminary patch for usb 2.0 ehci (rejected due to 
high res timer requirement). If I remember it correctly the usb 1.1 
worked reasonably on several webcams (mostly old ones, usb 1.1) and with 
low frames-per-second rate.

I guess since then there were some significant changes in the qemu usb 
code, so I cannot really answer your questions. Anyway, in the following 
week or two I will try to catch up with qemu current usb status and 
update you if I have any insight.

Forwarding your message to qemu-devel, so you may get some smarter answers.
 
Best Regards,
Arnon

Albert Orriols Puig wrote:
>
> Hi Arnon,
>
> I'm Albert Orriols-Puig, an assistant professor at La Salle -- Ramon 
> Llull University (in Spain). Recently, we have started using a 
> virtualization solution based on Open Suse + KVM + QEMU. Currently we 
> have some machines that use this software and host two Windows 
> operating systems: WinXP and Win7. The machines work quite well, that 
> is, we have a quite good performance in both guest OS.
>
> One of the key aspects that we need is to give support to webcams, 
> since our users usually employ skype or similar software to make phone 
> calls. However, we have realized that QEMU does not give direct 
> support for webcams. We have searched for different patches, and found 
> yours, which enables transfers in redirected host USB devices.
>
> We have tried your patch in a machine with the two aforementioned 
> hosts and a couple of logitech webcams. We have realized that the 
> guest OS detected the existence of a webcam, but could not show the 
> images of these webcams. In the WinXP system, the image was in black. 
> In the Win7, he detected the webcam but didn't allow using it since an 
> error popped up indicating that the webcam was blocked by another 
> application. We have searched for other patches that may help us, but 
> we were not successful.
>
> So, I'm contacting you to ask you a couple of questions. First, in the 
> patch notes it is mentioned that the system worked for some USB 1.1 
> and USB 2.0 cameras on XP. Do you remember some of the specific 
> webcams that you tried and worked? If so, could you tell me the models 
> and any tweak you needed to do in the guest OS side to make them work? 
> It would be great if we could make this work even if we have to adapt 
> to particular webcams.
>
> The second question is about the state of the progress on the support 
> of devices in QEMU. I've seen in some forums that there are some 
> people (including you ;)) working on QEMU to give support to different 
> devices. Do you know if there will be new releases to support USB 
> devices in a short time? We are specially interested in webcams, but 
> we would also need other devices as well.
>
> Let me thank you in advance for the time spend on reading this email!
>
>
> Best,
>
> Albert Orriols-Puig, PhD
> La Salle -- Universitat Ramon Llull
> email: aorriols@gmail.com
> web: http://www.albertorriols.net <http://www.albertorriols.net/>
>
>
>

Re: [Qemu-devel] Re: Webcam solution for QEMU

[Natalia Portillo]

Hello Arnon,
Hola Albert,

Wouldn't be easier to implement a custom video capture device?
You can always emulate a simple one, like (to say) OV511 webcam, and feed that emulated device with video taken from any V4L2/DirectShow/BDA supported device (real host webcam).

I think this way, timing issues will not arise, and will support indeed any webcam or video capture device (tuners) past, present, and future.

Of course not to say video will come with a little lag to the guest but that lag will be a lot less than the timing lag connecting host<->guest devices in a more directly way.

That's just my 2 euro cent.

Natalia Portillo

El 09/05/2010, a las 15:59, Arnon Gilboa escribió:

> Hello Albert,
> 
> First of all, I have done nothing in the qemu project for more than two years now. My last contribution to qemu were some usb 1.1 uhci/ohci patches for very basic support of webcams and other isochronous devices (accepted), and a preliminary patch for usb 2.0 ehci (rejected due to high res timer requirement). If I remember it correctly the usb 1.1 worked reasonably on several webcams (mostly old ones, usb 1.1) and with low frames-per-second rate.
> 
> I guess since then there were some significant changes in the qemu usb code, so I cannot really answer your questions. Anyway, in the following week or two I will try to catch up with qemu current usb status and update you if I have any insight.
> 
> Forwarding your message to qemu-devel, so you may get some smarter answers.
> Best Regards,
> Arnon
> 
> Albert Orriols Puig wrote:
>> 
>> Hi Arnon,
>> 
>> I'm Albert Orriols-Puig, an assistant professor at La Salle -- Ramon Llull University (in Spain). Recently, we have started using a virtualization solution based on Open Suse + KVM + QEMU. Currently we have some machines that use this software and host two Windows operating systems: WinXP and Win7. The machines work quite well, that is, we have a quite good performance in both guest OS.
>> 
>> One of the key aspects that we need is to give support to webcams, since our users usually employ skype or similar software to make phone calls. However, we have realized that QEMU does not give direct support for webcams. We have searched for different patches, and found yours, which enables transfers in redirected host USB devices.
>> 
>> We have tried your patch in a machine with the two aforementioned hosts and a couple of logitech webcams. We have realized that the guest OS detected the existence of a webcam, but could not show the images of these webcams. In the WinXP system, the image was in black. In the Win7, he detected the webcam but didn't allow using it since an error popped up indicating that the webcam was blocked by another application. We have searched for other patches that may help us, but we were not successful.
>> 
>> So, I'm contacting you to ask you a couple of questions. First, in the patch notes it is mentioned that the system worked for some USB 1.1 and USB 2.0 cameras on XP. Do you remember some of the specific webcams that you tried and worked? If so, could you tell me the models and any tweak you needed to do in the guest OS side to make them work? It would be great if we could make this work even if we have to adapt to particular webcams.
>> 
>> The second question is about the state of the progress on the support of devices in QEMU. I've seen in some forums that there are some people (including you ;)) working on QEMU to give support to different devices. Do you know if there will be new releases to support USB devices in a short time? We are specially interested in webcams, but we would also need other devices as well.
>> 
>> Let me thank you in advance for the time spend on reading this email!
>> 
>> 
>> Best,
>> 
>> Albert Orriols-Puig, PhD
>> La Salle -- Universitat Ramon Llull
>> email: aorriols@gmail.com
>> web: http://www.albertorriols.net <http://www.albertorriols.net/>
>> 
>> 
>> 
> 
> 
> 

Re: [Qemu-devel] Re: Webcam solution for QEMU

[David Ahern]

On 05/09/2010 08:28 PM, Natalia Portillo wrote:
> Hello Arnon,
> Hola Albert,
> 
> Wouldn't be easier to implement a custom video capture device?
> You can always emulate a simple one, like (to say) OV511 webcam, and feed that emulated device with video taken from any V4L2/DirectShow/BDA supported device (real host webcam).
> 
> I think this way, timing issues will not arise, and will support indeed any webcam or video capture device (tuners) past, present, and future.
> 
> Of course not to say video will come with a little lag to the guest but that lag will be a lot less than the timing lag connecting host<->guest devices in a more directly way.
> 
> That's just my 2 euro cent.


Earlier this year I got a streaming audio device to work as a
passthrough device. The biggest pain was needing to modify the guest
driver to increase its number of outstanding URBs. That was required due
to the way isochronous requests are handled within the USB controller.

Based on that experience I thought an emulated device in qemu would help
with the low level timing issues. In addition it would provide an option
for VDI wherein the VM on a remote server is running a video/audio
streaming ap that requires webcam interaction (e.g., video phone or
integrated conferencing software).

Are you planning to create such a device for qemu?

David