Added basic playlist support

[cternes]

I've added audio support for a playlist, meaning playing a list of sounds one after another. This could be useful to create a playlist of a game soundtrack.

[ghost]

Hi @cternes , i put this into the feature list, if you can provide more detail about this for example:
how to fully use it, and all available options. In the next version if we add it, your name will be put as author of this feature.
Thank You :D

[mpkorstanje]

This looks wrong. The callback shouldn't be invoked when passed to the event listener. Also listener should be removed after use. Should look like this:

        var endedListener = function(){
          Q.audio.channels[i].channel.removeEventListener('ended', endedListener);  
          callback();
        }
        Q.audio.channels[i].channel.addEventListener('ended', endedListener);

[mpkorstanje]

Just tested this.

Play list itself works, but bugs happen when the play list is stopped. Call back to start next song is called on timeout, even when the song has been stopped.

I need this functionality. So I'll probably end up fixing it.

[ghost]

Maybe a separate module would be good idea

[mpkorstanje]

I dunno yet.

Right now the problem I'm trying to solve is that there two different cases that result in the same events.

Case A: Audio is finished, audio triggers audio stopped event / timeout ---> callback is invoked.
Case B: Audio is stopped, audio triggers audio stopped event / timeout (minutes after the fact) --> callback is invoked

Right now I'm seeing if I can make use the event system from Q and inform listeners about audio events. 'stopped.audioFilename' and 'finished.audioFileName'.

This looks pretty clean and would allow playlists to be a module more easilly, but I'm worried that it might be slow and overengineerd. It also has the problem that there is no good identity for songs, the same file (name) can be playing on multiple tracks.

The alternative would be to remove callback when a song is stopped, which is simple and fast but ties the play lists strongly to audio.

Still I'm prefering the former. It is more flexible and allows more things to be done with Audio.