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From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] hw/usb/dev-audio.c: make USB audio card
	sound perfect
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Programmingkid <programmingkidx@gmail.com>, "H. Peter Anvin" <hpa@linux.intel.com>, qemu-devel qemu-devel <qemu-devel@nongnu.org>, spice-devel <spice-devel@freedesktop.org>

  Hi,

> > Higher chance is with video playback.  lip sync issues might show up,
> > although you probably still have to watch carefully to actually notice.
> 
> Regarding the video playback workload: video playback is not a
> low-latency audio use case.  That's why you won't notice any difference
> if the USB audio device has a larger buffer size.

Well, yes, it isn't low-latency indeed, but probably still sensitive to
the buffer size.  The buffer we are talking about here is a pure
host-side thing, the guest doesn't know it exists and how big it is.

> This can be implemented with large audio buffers,

Yes, but for that the player needs to know how big the buffer is so the
audio clock math is correct ...

cheers,
  Gerd