From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=48169 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OCEX8-00008k-Ic for qemu-devel@nongnu.org; Wed, 12 May 2010 12:11:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OCEX2-00080K-EQ for qemu-devel@nongnu.org; Wed, 12 May 2010 12:11:42 -0400 Received: from mail-ww0-f47.google.com ([74.125.82.47]:47951) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OCEX1-0007zw-9G for qemu-devel@nongnu.org; Wed, 12 May 2010 12:11:36 -0400 Received: by wwb39 with SMTP id 39so122790wwb.34 for ; Wed, 12 May 2010 09:11:32 -0700 (PDT) Message-ID: <4BEAD330.9070106@gmail.com> Date: Wed, 12 May 2010 10:11:28 -0600 From: David Ahern MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: Webcam solution for QEMU References: <4BE520D9.1080400@gmail.com> <4BE6CDBB.2090401@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Natalia Portillo Cc: Albert Orriols Puig , uri lublin , Jonathan Blandford , Arnon Gilboa , qemu-devel 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