多个声道播放多个WAV AVAudioEngine
问题描述:
我有15个WAV文件,需要按顺序播放各个频道。我开始尝试使用左/右立体声分离处理两个文件。多个声道播放多个WAV AVAudioEngine
我正在创建一个音频引擎,一个混音器和两个AVAudioPlayerNodes。音频文件是单声道的,我试图从PlayerA得到文件出来左边的频道,并从PlayerB的文件出来右边的频道。我无法理解的是AudioUnitSetProperty是如何工作的。它似乎只涉及单个文件,似乎只能有一个每个audioUnit?我想知道是否有一种方法可以将文件与audioUnit关联起来?我似乎无法返回与每个轨道关联的audioUnit对象。
func testCode(){
// get output hardware format
let output = engine.outputNode
let outputHWFormat = output.outputFormat(forBus: 0)
// connect mixer to output
let mixer = engine.mainMixerNode
engine.connect(mixer, to: output, format: outputHWFormat)
//then work on the player end by first attaching the player to the engine
engine.attach(playerA)
engine.attach(playerB)
//find the audiofile
guard let audioFileURLA = Bundle.main.url(forResource: "test", withExtension: "wav") else {
fatalError("audio file is not in bundle.")
}
guard let audioFileURLB = Bundle.main.url(forResource: "test2", withExtension: "wav") else {
fatalError("audio file is not in bundle.")
}
var songFileA:AVAudioFile?
do {
songFileA = try AVAudioFile(forReading: audioFileURLA)
print(songFileA!.processingFormat)
// connect player to mixer
engine.connect(playerA, to: mixer, format: songFileA!.processingFormat)
} catch {
fatalError("canot create AVAudioFile \(error)")
}
let channelMap: [Int32] = [0, -1] //play channel in left
let propSize: UInt32 = UInt32(channelMap.count) * UInt32(MemoryLayout<sint32>.size)
print(propSize)
let code: OSStatus = AudioUnitSetProperty((engine.inputNode?.audioUnit)!,
kAudioOutputUnitProperty_ChannelMap,
kAudioUnitScope_Global,
1,
channelMap,
propSize);
print(code)
let channelMapB: [Int32] = [-1, 0] //play channel in left
var songFileB:AVAudioFile?
do {
songFileB = try AVAudioFile(forReading: audioFileURLB)
print(songFileB!.processingFormat)
// connect player to mixer
engine.connect(playerB, to: mixer, format: songFileB!.processingFormat)
} catch {
fatalError("canot create AVAudioFile \(error)")
}
let codeB: OSStatus = AudioUnitSetProperty((engine.inputNode?.audioUnit)!,
kAudioOutputUnitProperty_ChannelMap,
kAudioUnitScope_Global,
1,
channelMapB,
propSize);
print(codeB)
do {
try engine.start()
} catch {
fatalError("Could not start engine. error: \(error).")
}
playerA.scheduleFile(songFileA!, at: nil) {
print("done")
self.playerA.play()
}
playerB.scheduleFile(songFileA!, at: nil) {
print("done")
self.playerB.play()
}
playerA.play()
playerB.play()
print(playerA.isPlaying)
}
答
engine.connect(混频器,以:输出,格式:outputHWFormat)
这是没有必要的,混频器将被隐式访问时连接。
至于平移:AudioUnitSetProperty也是没有必要的。 AVAudioPlayerNode符合AVAudioMixing,这样以来有来自玩家下游的混频器节点,所有你需要做的是这样的:
playerA.pan = -1
playerB.pan = 1
感谢您的建议戴夫。我曾经看过泛功能,但我最终试图将15个文件输出到15个独立的频道,因此无法在该应用程序中进行平移。 – tsugua