Set AudioFilePlayer AU stream format

SetStreamFormat.c

// Get the ASBD from the player unit
UInt32 playerASBDsz;
checkError(AudioUnitGetProperty(_playerUnit,
                                kAudioUnitProperty_StreamFormat,
                                kAudioUnitScope_Output,
                                BUS_PLAYER_OUTPUT,
                                &_playerASBD,
                                &playerASBDsz),
           "AudioUnitSetProperty failed: getting stream format from the player unit", false);

// Update with channels and sample rate from the main application:
_playerASBD.mChannelsPerFrame = _outputASBD.mChannelsPerFrame;
_playerASBD.mSampleRate = _outputASBD.mSampleRate;

// Re-apply the ASBD to the player unit
checkError(AudioUnitSetProperty(_playerUnit,
                                kAudioUnitProperty_StreamFormat,
                                kAudioUnitScope_Output,
                                BUS_PLAYER_OUTPUT,
                                &_playerASBD,
                                sizeof(_playerASBD)),
           "AudioUnitSetProperty failed: setting channels & sample rate to player output ASBD", false);