[Spice-devel] [PATCH v2] sndworker: add AudioVolume/AudioMute messages

[Marc-André Lureau]

Hi,

On Tue, Jun 21, 2011 at 10:48 AM, Christophe Fergeau
<cfergeau at redhat.com> wrote:
> On Tue, Jun 21, 2011 at 12:05:56AM +0200, Marc-André Lureau wrote:
>> So, the answer in short is that I don't know, but I know it can be
>> addressed later, for example when we use dB, which is way better for
>> emulated hw. But that needs even more work, I wanted the basics first.
>
> The thing is, once it's added to the protocol, we'll have to keep it around
> forever. So do we have a clear way to go from what you suggest to the
> future/better scale in dB? Ie will we add one more field in dB and fill
> both the old and new values, will we add capabilities check to know the
> format of the field, or is it something that you were planning to think
> about later?
>

The added volume/mute are not a criticial part of the protocol, it is optionnal.

So we can simply change the message "volume" in % to "volume_db" in
dB, if both parts say they have the capability to handle volume in dB.
That's roughly what I had in mind. I don't see major problems with
having both messages in % and dB simultaneously either, that's what
PulseAudio does, afaik: pro-audio UI will use dB, while volume sliders
for status & players use an arbitrary % scale. PA scale however,
allows to amplify above 100%. But in our case, the emulated hardware
doesn't allow this, and we could map Spice 0..100% to a different
scale on the client side: 0..300%. The client is free to do whatever
with the Spice scale basically.

regards

-- 
Marc-André Lureau