/*

    File: MixerHostAudio.h

Abstract: Audio object: Handles all audio tasks for the application.

 Version: 1.0

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*/

#import <AudioToolbox/AudioToolbox.h>

#import <AVFoundation/AVFoundation.h>

#define NUM_FILES 2

// Data structure for mono or stereo sound, to pass to the application's render callback function, 

//    which gets invoked by a Mixer unit input bus when it needs more audio to play.

typedef struct {

    BOOL                 isStereo;           // set to true if there is data in the audioDataRight member

    UInt32               frameCount;         // the total number of frames in the audio data

    UInt32               sampleNumber;       // the next audio sample to play

    AudioUnitSampleType  *audioDataLeft;     // the complete left (or mono) channel of audio data read from an audio file

    AudioUnitSampleType  *audioDataRight;    // the complete right channel of audio data read from an audio file

} soundStruct, *soundStructPtr;

@interface MixerHostAudio : NSObject <AVAudioSessionDelegate> {

    Float64                         graphSampleRate;

    CFURLRef                        sourceURLArray[NUM_FILES];

    soundStruct                     soundStructArray[NUM_FILES];

    // Before using an AudioStreamBasicDescription struct you must initialize it to 0. However, because these ASBDs

    // are declared in external storage, they are automatically initialized to 0.

    AudioStreamBasicDescription     stereoStreamFormat;

    AudioStreamBasicDescription     monoStreamFormat;

    AUGraph                         processingGraph;

    BOOL                            playing;

    BOOL                            interruptedDuringPlayback;

    AudioUnit                       mixerUnit;

}

@property (readwrite)           AudioStreamBasicDescription stereoStreamFormat;

@property (readwrite)           AudioStreamBasicDescription monoStreamFormat;

@property (readwrite)           Float64                     graphSampleRate;

@property (getter = isPlaying)  BOOL                        playing;

@property                       BOOL                        interruptedDuringPlayback;

@property                       AudioUnit                   mixerUnit;

- (void) obtainSoundFileURLs;

- (void) setupAudioSession;

- (void) setupStereoStreamFormat;

- (void) setupMonoStreamFormat;

- (void) readAudioFilesIntoMemory;

- (void) configureAndInitializeAudioProcessingGraph;

- (void) startAUGraph;

- (void) stopAUGraph;

- (void) enableMixerInput: (UInt32) inputBus isOn: (AudioUnitParameterValue) isONValue;

- (void) setMixerInput: (UInt32) inputBus gain: (AudioUnitParameterValue) inputGain;

- (void) setMixerOutputGain: (AudioUnitParameterValue) outputGain;

- (void) printASBD: (AudioStreamBasicDescription) asbd;

- (void) printErrorMessage: (NSString *) errorString withStatus: (OSStatus) result;

@end