AVPlayer can change the app's audio session under MumbleKit's feet

[mkrautz]

From an email:

MumbleKit was using Opus as its encoder and Opus only supports a few sample rates, in MumbleKit's
case, 48000hz. When playing a 44.1khz aac file with AVPlayer the remoteio's input callback would
start erring at AudioUnitRender because AVPlayer had fiddled with the AVSessions samplerate.
The way I was finally able to play AVPlayer while MumbleKit was running was to reencode my aac
files being played to match the samplerate of the input callback, 48000.