From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: USB Passthrough 1.1 performance problem...
Date: Mon, 13 Dec 2010 11:36:27 +0100
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References: <4D04B645.3010100@brakkee.org>
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To: Erik Brakkee <erik@brakkee.org>
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   Hi,

> I am using a tv card in a VM and get jerky video.As I understand it, the
> VM is using USB 1.1. However, when I set the USB controller in the BIOS
> of my server to Fullspeed (12 Mbit/s) which is the USB 1.1 speed I am
> able to get perfect results on the host but still on the guest the video
> is jerky.

There is a patch series from Hans de Goede on qemu-devel which adds 
buffering for isochronous usb transfers to the usb passthrough code. 
Certainly worth a try.

cheers,
   Gerd