Add a setting to enable audio passthrough
There is no API (or maybe I missed it) to detect if an audio codec is supported by CoreAudio.
Therefore, users should explicitly enable audio passthrough by themselves if they want it. Detecting if the AudioRoute is a HDMI one is not enough since TV and amplifiers don't have to support every codecs.
To enable audio passthrough:
libvlc_audio_output_device_set(mp, NULL, "encoded");
To disable it:
libvlc_audio_output_device_set(mp, NULL, "pcm");