Re: Sound system - user perspective

[Stefan Kost <ensonic hora-obscura de>]

Lennart Poettering schrieb:
> On Sun, 13.09.09 19:18, Maciej Piechotka (uzytkownik2 gmail com) wrote:
> 
>> I spotted an area in which Gnome desktop can offer better user
>> experience.
>>
>> Imagine I use VoIP (skype, empathy or anything like that) and some music
>> player (Banshee, Rhythmbox etc.). I listen to some music or a podcast
>> when someone ring.
>>
>> I have to stop the music and answer the phone. However I guess that
>> music/podcast should actually be paused (i.e. state in application
>> should be stopped) instead of being just volume down. 
>>
>> I'm not sure if current architecture would allow such integration and
>> probably it would require changes to few packages (music player and
>> empathy at least) I prefer to post the idea here firstly. 
> 
> This logic is actually already supported in PulseAudio and activated
> by default.
> 
> This all depends on that applications properly tag their audio
> streams, i.e. so that it is clear which stream is telephony, which one
> is event sounds, and which one is music. Some apps have now started to
> do this properly. In fact the next beta of Skype will do this too. And
> if your favourite telephony or music app still doesn't then please
> complain and file a bug and ask them to read this:
> 
>      http://0pointer.de/blog/projects/tagging-audio.html
> 
> and this:
> 
>      http://pulseaudio.org/wiki/ApplicationProperties
> 
> The logic in PA will mute every stream tagged as "music" as soon as a
> stream tagged as "phone" is active. It will also send an asynchronous
> event to each music playing client requesting that it should pause its
> playback. If the "phone" stream goes away the "music" streams will be
> unmuted again and the apps notified that it is a good idea to unpause
> playback again.
> 
> Unfortunately GStreamer does not have a nice API for tagging streams
> yet (this limitation can be circumvented via using environment
> variables which PA will pick up, but that's not a very nice
> solution). Also, GStreamer does not actually forward the pause request
> message to the applications and hence you'll effectively only see the
> muting taking happen, not the pause/unpause in current media players.
> 
> To make this all work nicely jut a little bit glue code needs to be
> written for Gst and some minor patches be prepared for the various
> telephony apps/media players. If someone wants to pick this up and
> push this through this would be really great!

THis is the one about tagging the stream, right
https://bugzilla.gnome.org/show_bug.cgi?id=567656
It would be easy to implement. The reason its stalled is that as gstreamer is
abstracting various technologies, we neeed to study where this could apply and
if it's generic enough.

Lennart, is there is ticket about the pause? I still wonder how it should be
done (just forwarding to the app so that it will pause the pipeline). Also
wonder if simmilar features could be mapped to other technologies. Finally we
ned to figure how to merge such events, as e.g. a video editor might get this
for a recording source and the playback sink (despite that a phone call should
not interruppt a recoding session, but there is a category for that too).

Stefan

> 
> Lennart
>