Re: Switching output sink(?)

[Mandar Mitra]

That's a lot of inputs, thanks very very much! It'll take me a while to digest 
and try out your various suggestions. I expect to report back within a week.

-mandar


Mike Kazantsev wrote (Fri, Oct 30, 2020 at 10:07:22PM +0500):
> On Fri, 30 Oct 2020 22:01:43 +0530
> Mandar Mitra <mandar.mitra@gmail.com> wrote:
> 
> > I can use the mate volume control applet to switch between the
> > builtin speakers on my computer and an external speaker connected via
> > bluetooth.
> > Other applications like Firefox and mpv (played from the command-line)
> > send the output to whatever is currently selected as the sound sink,
> 
> With mpv this should probably happens when you start a fresh instance,
> so it selects new default sink, but if you start mpv before switching,
> it won't auto-migrate running playback stream to a new sink, correct?
> 
> 
> > but emms seems to always send output to the default builtin speaker,
> > even when a bluetooth speaker is connected and selected in the volume
> > control applet.
> 
> If you use mpv as a player in emms, then it should use a long-running
> mpv process that doesn't get restarted between tracks by default.
> 
> It does however close and re-open the output stream for each track,
> which might play on the new default sink, so that might be a hacky fix,
> if the issue is only with currently-playing stuff - hit "stop" and then
> "play" key.
> Not a nice fix though, obviously.
> 
> (not entirely sure if mpv/libpulse will use different sink for new
> stream, but it probably should, unless directed to do otherwise via
> e.g. PULSE_SINK env option)
> 
> 
> > I can probably use the discussion here
> > 
> > https://askubuntu.com/questions/71863/how-to-change-pulseaudio-sink-with-pacmd-s
> > et-default-sink-during-playback
> > 
> > and cobble together an elisp function to run the necessary shell commands, 
> > but
> > don't know how to integrate this into emms.
> 
> To be clear, one of the essential commands that you're talking about is
> something like "pactl move-sink-input 5 1"?
> I.e. to move currently-playing music stream to a new sink?
> 
> As I assume that you change default sink in the desktop environment
> applet already (as otherwise not sure what else it might be doing),
> so there's no need to run that part from the link.
> 
> 
> > Could you please give me a hint or two -- maybe point me to which .el files 
> > I
> > should look at for more info? Or let me know that this is not easily doable?
> 
> Do you want emacs or emms to detect when default sink in pulseaudio
> changes and migrate running mpv playback stream to a new default sink?
> 
> Don't think it has much to do with emms, as it doesn't monitor
> pulseaudio state in any way, and doesn't really know that it even
> exists, as only mpv interacts with it, if it is the output configured
> there.
> 
> I'd suggest these options:
> 
> - Checking DE volume applet for some hook that it might run when
>   changing sinks and adding a script there to also migrate any running
>   streams.
> 
> - Contacting applet devs, asking if there's an option to do that, and
>   maybe considering adding it, as it sounds generally useful.
> 
> - Making a script that'd do that independently of emms (as again, it
>   shouldn't have much to do with this).
> 
>   For example, with shell, guess you can monitor "pactl subscribe"
>   output and react to relevant sink state changes there.
>   Or you can make same script with e.g. python, elisp or in any other
>   language, of course, some of which have more convenient libpulse
>   bindings.
> 
> But feel like maybe I've misunderstood the question, given how it seem
> to be directed to this mailing list, while having little to do with
> emms in my current understanding.
> 
>