Swift：OpenALでcaf音源を鳴らす方法

はじめに

ゲームなど速いレスポンスが必要な場合OpenALで音を鳴らすのが良いらしいことを知ったので、OpenALでcaf音源を鳴らすクラスを作成した。

ソースコード

OpenALUtil.swift

import OpenAL
import AudioToolbox

class OpenALUtil {
	var buffer: ALuint = 0
	var source: ALuint = 0

	init(fileName name: String) {
		let device = alcOpenDevice(nil)
		let context = alcCreateContext(device, nil)
		alcMakeContextCurrent(context)

		alGenBuffers(1, &buffer)
		let error: ALenum = alGetError()
		if error != AL_NO_ERROR {
			Swift.print(error.description)
			return
		}

		//open audio-file
		var fileId: AudioFileID? = nil
		let url: CFURL = URL(fileURLWithPath: Bundle.main.path(forResource: name, ofType: "caf")!) as CFURL
		let _: OSStatus = AudioFileOpenURL(url, .readPermission, kAudioFileCAFType, &fileId)

		//get byte-size of audio-file
		var byteCount: UInt64 = 0
		var propertySize = UInt32(MemoryLayout.size(ofValue: byteCount))
		let _: OSStatus = AudioFileGetProperty(fileId!, kAudioFilePropertyAudioDataByteCount, &propertySize, &byteCount)

		//read audio-file
		var bytesRead = UInt32(byteCount)
		let audioData = malloc(Int(bytesRead))!
		let _: OSStatus = AudioFileReadBytes(fileId!, false, 0, &bytesRead, audioData)

		//close audio-file
		let _: OSStatus = AudioFileClose(fileId!)

		//data into buffer
		alGenBuffers(1, &buffer)
		alBufferData(buffer, AL_FORMAT_MONO16, audioData, ALsizei(bytesRead), 44100)

		//write buffer to source
		alGenSources(1, &source)
		alSourcei(source, AL_LOOPING, AL_TRUE)
		alSourcei(source, AL_BUFFER, ALint(buffer))
	}

	public func play() {
		alSourcePlay(source)
	}

	public func pause() {
		alSourcePause(source)
	}

	public func stop() {
		alSourceStop(source)
	}
}

このClassの使い方

ViewController.swift

let sound = OpenALUtil(fileName: "click") //click.cafを指定
sound.play() //再生
sound.pause() //一時停止
sound.stop() //停止