Separate out audio functionality

[dsvensson]

It would be great if audio functionality would be split out into a separate module to enable headless mode where the use is only data rather than playback.

[devgianlu]

What do you mean by data?

[dsvensson]

I guess I interpreted this as a library rather than an application and it was a bit unexpected that for example the argument to FileConfiguration was the actual string "--conf-file=...", and that it opened an audio device, but perhaps librespot is more thought of as librespot, completely geared towards reproducing a Spotify Desktop Client like app?

I was just interested in writing a cli to search with. Seems like setting the [player] output = "STDOUT" got rid of the mixer probing. Haven't tried running it with a headless JVM yet, but perhaps that'll work now.

Still having some issues with shutdown, seems like some OkHttp thread lingers even after calling session.close().

[devgianlu]

You're right, the name is a bit confusing because this is a fully fletched player with library features all merged together. While I like the idea of separating the API part of the project into a different module, I need to combat piracy (low effort piracy) by avoiding to expose crucial parts which can be exploited. That is feasible though.

Setting the output to STDOUT will get rid of the mixer problem and won't output anything as long as you don't ask it to.

Still having some issues with shutdown, seems like some OkHttp thread lingers even after calling session.close().

As I don't use the project as a library specifically I tend to leave those behind, please open a separate issue or PR and I'll sort it out.

[dsvensson]

@devgianlu Humm.... I wonder if it performs close() on stdout then when issuing session.close(), last line of that function, Closed session. {deviceId: %s} , never reaches the console :)

[devgianlu]

It was indeed closing STDOUT so I fixed that, but the issue remains if the library is closed with Ctrl-C because the logger threads are shutdowned too.

[devgianlu]

Closing in favor of #245.