standinga

import Cocoa
import AUFramework

class ViewController: NSViewController {
    
    private var audioPlayer: AudioPlayer!
    private var pluginVC: AudioUnitViewController!
    
    @IBOutlet weak var auContainer: NSView!
    

standinga

import CoreAudioKit

public class AudioUnitViewController: AUViewController, AUAudioUnitFactory {
    public var audioUnit: VolumePluginAudioUnit? {
        didSet {
            DispatchQueue.main.async {
                if self.isViewLoaded {
                    self.connectWithAU()
                }
            }

standinga

#import <AVFoundation/AVFoundation.h>
struct Buffer {
    AVAudioPCMBuffer *pcmBuffer = nullptr;
    AudioBufferList* mutableAudioBufferList = nullptr;
    AudioBufferList const* originalAudioBufferList = nullptr;
    AUAudioFrameCount maxFrames = 0;
    float volume = 1.0;
    
    /*
     prepareInputBufferList populates the mutableAudioBufferList with the data

standinga

public func selectAudioUnitWithComponentDescription(_ componentDescription: AudioComponentDescription?, completionHandler: @escaping (() -> Void)) {
        // Internal function to resume playing and call the completion handler.
        func done() {
            if isPlaying {
                playerNode.play()
            }
            completionHandler()
        }
        
        let hardwareFormat = self.engine.outputNode.outputFormat(forBus: 0)

standinga

private func connectAudioUnitWithPlayer() {
        var componentDescription = AudioComponentDescription()
        componentDescription.componentType = kAudioUnitType_Effect
        // used https://codebeautify.org/string-hex-converter to convert strings to fourCC hex
        componentDescription.componentSubType = 0x44656d6f // "Demo"
        componentDescription.componentManufacturer = 0x44656d6f // "Demo"
        componentDescription.componentFlags = 0
        componentDescription.componentFlagsMask = 0
        
        AUAudioUnit.registerSubclass(VolumePluginAudioUnit.self, as: componentDescription, name: "demo: VolumePlugin", version: UInt32.max)

standinga

// Define parameter addresses.
const AudioUnitParameterID myParam1 = 0;

@interface VolumePluginAudioUnit ()

@property (nonatomic, readwrite) AUParameterTree *parameterTree;
@property AUAudioUnitBus *inputBus;
@property AUAudioUnitBus *outputBus;
@property AUAudioUnitBusArray *inputBusArray;
@property AUAudioUnitBusArray *outputBusArray;

standinga

- (instancetype)initWithComponentDescription:(AudioComponentDescription)componentDescription options:(AudioComponentInstantiationOptions)options error:(NSError **)outError {
    self = [super initWithComponentDescription:componentDescription options:options error:outError];
    
    if (self == nil) { return nil; }
    
    // initialize Buffer
    _buffer = Buffer();
    _buffer.maxFrames = 0;
    _buffer.pcmBuffer = nullptr;
    _buffer.mutableAudioBufferList = nullptr;

standinga

- (BOOL)allocateRenderResourcesAndReturnError:(NSError **)outError {
    if (![super allocateRenderResourcesAndReturnError:outError]) {
        return NO;
    }
    
    // Validate that the bus formats are compatible.
    if (self.outputBus.format.channelCount != _inputBus.format.channelCount) {
        if (outError) {
            *outError = [NSError errorWithDomain:NSOSStatusErrorDomain code:kAudioUnitErr_FailedInitialization userInfo:nil];
            NSLog(@"kAudioUnitErr_FailedInitialization at %d", __LINE__);

standinga

- (AUInternalRenderBlock)internalRenderBlock {
    // Capture in locals to avoid ObjC member lookups. If "self" is captured in render, we're doing it wrong. See sample code.
    __block Buffer* buffer = &_buffer;
    
    return ^AUAudioUnitStatus(AudioUnitRenderActionFlags *actionFlags, const AudioTimeStamp *timestamp, AVAudioFrameCount frameCount, NSInteger outputBusNumber, AudioBufferList *outputData, const AURenderEvent *realtimeEventListHead, AURenderPullInputBlock pullInputBlock) {
        // Do event handling and signal processing here.
        AudioUnitRenderActionFlags pullFlags = 0;
        buffer->prepareInputBufferList();
        AUAudioUnitStatus err = pullInputBlock(&pullFlags, timestamp, frameCount, 0, buffer->mutableAudioBufferList);
        

standinga

import AVFoundation

class AudioPlayer: NSObject {
    
    private let engine = AVAudioEngine()
    private let playerNode = AVAudioPlayerNode()
    private var file: AVAudioFile!
    private var isPlaying = false
    private let audioPlayerQueue = DispatchQueue(label: "AudioPlayerQueue")