[pulseaudio-discuss] limits on maximum device volume?

[Lennart Poettering]

On Mon, 27.04.09 13:04, CJ van den Berg (cj at vdbonline.com) wrote:

> On Sat, Apr 25, 2009 at 02:53:30AM +0200, Lennart Poettering wrote:
> > What this boils down to is: 
> > 
> >   If you change the volume of a stream, you just change the volume of
> >   that one stream for now and for the future. It won't have any effect
> >   on the volume of *other* existing or future streams.
> > 
> >   If you change the volume of a sink, you change the volume of all
> >   streams on it at the same time for now and for the future. It will
> >   have a direct effect on existing or future streams.
> 
> That might be the *intended* behaviour, but the current pulseaudio in
> rawhide definitely doesn’t actually work that way. Let walk you through
> what happens here:
> 
> 1. Sink volume 60%, with no streams playing. Just to be sure I move it
> manually to 65%.
> 
> 2. Start an mpd stream. Sink volume drops to 37% (why?). Mpd’s stream
> volume is also 37%.

PA remembers the volume of your stream relative to the sink volume. If
you slide the stream volume to where it translates to a
multiplifcation factor relative to the sink of -- let's say -- 0.6,
and then disconnect, change the sink slider and reconnect, PA will set
the stream volume to 0.6 of the *new* sink volume.

(Note however that volumes in percantages are not multiplication
factors, so don't do calculations with the percentages!)

> 3. 37% is too low, so I turn up the sink volume to 65% again. Mpd’s
> stream volume also moves to 65%.
> 
> 4. I stop the MPD stream. The sink volume stays at 65%.

Yes, if you change the sink volume this will become the new reference
volume, and be fed back to the stream volume. In this case the stream
value is afterwards identical to the sink volume and the factor hence 1.0.

> 5. Start totem. Sink volume jumps to 85% (and blows my eardrums).
> Totem’s stream volume is also 85%.

Last time you apparently configured the totem volume to a factor that
was higher then the reference volume (i.e. > 1.0). Hence PA will
restore that this way, too.

> 6. Stop totem. Sink volume drops to 65% (huh?).

You didn't change the reference volume (because the refernce volume is
only changed when you adjust the sink volume) and hence it will drop
back to the reference volume in the UI when no stream is connected.

> Now, in step 3 I clearly set the *sink* volume manually to 65%. Which
> pulse apparently ignored when the totem stream started. I don’t see how
> this fits into your described behaviour above. The net effect of all
> this is that the sink volume jumps around, pretty much on every new
> stream startup. Which is annoying as hell.

PA didn't ignore that. It however applied the relative stream volume
of the last totem run to the new sink volume.

It does make a lot of sense the way it is. But I must admit that it is
still not particularly easy to grok, i.e. user-friendly.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4