Re: [virtio-dev] Re: [PATCH v3] virtio-snd: add virtio sound device specification

[Anton Yakovlev <anton.yakovlev@opensynergy.com>]

On 20.12.2019 13:41, Gerd Hoffmann wrote:
>    Hi,
>
> > > Period notification would be implicit (playback buffer completion) or
> > > explicit event queue message?
> >
> > Good question. I think, for message-base transport they would be implicit,
> > since we will require to enqueue period_size length buffers. The only
> > exception here will be the end of the stream for playback.
>
> Why is the end-of-stream different?

Since, as in the case of the input stream, the last buffer may contain less
than period_bytes of data.


> > > Not sure if we want add more properties.  hda codecs can also specify
> > > the color coding of physical jacks (line-in is red, ...) for example.
> > > Probably not useful for most use cases (i.e. when sound data lands @
> > > pulseaudio where the user can re-route things as he wants), but it might
> > > be useful when a fixed physical host output is assigned to the guest.
> >
> > Well, if we are gonna introduce jacks colors, then we should introduce a jack
> > entity itself. Like, define some kind of jack descriptor, enumerate all
> > available jacks for the stream, putting into the descriptor its color and
> > other properties, maybe allow jack hotplug/unplug, etc.
>
> We also need routing then (enable/disable jacks per stream), and link
> detection (is something plugged into the jack?) could be useful too.
>
> Should we make that an optional extension (and possibly hash out these
> details later)?  If you assign host machine jacks to your guest all this
> is useful.  If your guests's sound is routed to pulseaudio for playback
> not so much.

Yeah, we can put it off for later. In addition, in the case of PA, sinks and
sources can be moved, added and removed dynamically, so some logic with jacks
might be useful there as well.


> Note: I'll be offline for xmas and new year until january.

Happy holidays!


--
Anton Yakovlev
Senior Software Engineer

OpenSynergy GmbH
Rotherstr. 20, 10245 Berlin

Phone: +49 30 60 98 54 0
E-Mail: anton.yakovlev@opensynergy.com