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Re: [Qemu-devel] [PATCH 0/6] The windows 7 audio support patch series.
From: |
malc |
Subject: |
Re: [Qemu-devel] [PATCH 0/6] The windows 7 audio support patch series. |
Date: |
Thu, 28 Oct 2010 13:46:53 +0400 (MSD) |
User-agent: |
Alpine 2.00 (LNX 1167 2008-08-23) |
On Thu, 28 Oct 2010, Gerd Hoffmann wrote:
> Hi,
>
> > Nice timing there. I wonder how long it took bright folks at redhat to
> > code this HDA stuff?
>
> A bunch of days. Played with the usb-audio patch first. But I suspect
> getting timing-sensitive isochronous usb devices emulated reasonable well is
> pretty hard due to the latency requirements. And it isn't just the usb
> subsytem, all qemu must improve here. Example: enabling the threaded vnc
> server improves usb-audio sound quality, you don't get dropouts on every bulky
> screen update then.
We (me, Wu Fengguang and Hans Peter Anvin) tried to do something about
usb-audio, to no avail.
>
> But for now I tried HDA route instead.
>
> > Since yesterday i was contacted by folks who wanted
> > to pay money to get VirtualBox's HDA ported to QEMU, and it took me from
> > 16:00 today till basically 15 minutes ago to get the sound pumping from
> > DOS and Linux..
>
> Oh, there is a HDA driver for DOS? /me looks surprised ...
DOS doesn't need drivers you know, anyhow:
http://mpxplay.sourceforge.net/
>
> > Regardless of the answer to my question the NIH is such a nice thing, eh?
>
> Sure ;) I don't do that just for fun though. I *have* looked at the vbox
> driver first.
>
> The fundamental problem is the qemu world didn't stop at the point where vbox
> forked off, and of course in vbox things are changing too. We have alot of
> infrastructure for drivers which isn't in vbox, and likewise the other way
> around. Most notable difference is qemu's qdev is quite useful to model the
> HDA bus.
>
> So there are basically two options:
>
> (1) Port the vbox driver to qemu, then to tons of changes and
> cleanups to properly integrate into modern qemu.
> (2) Start over from scratch.
>
> I believe in the end it wouldn't have saved work to use the vbox code as
> starting point.
At the very least their code does work here (on a PPC with DOS and
mpxplay) and yours doesn't. I'd have to check things on my x86_64 box
to ensure it's not a endianness issue of some sort, otherwise things
are hard to explain since mpxplay's hda handling is based on ALSA.
--
mailto:address@hidden
- [Qemu-devel] Re: [PATCH 5/6] Add support for a USB audio device model, (continued)
[Qemu-devel] [PATCH 6/6] Add Intel HD Audio support to qemu., Gerd Hoffmann, 2010/10/27
Re: [Qemu-devel] [PATCH 0/6] The windows 7 audio support patch series., malc, 2010/10/27