在 IOS 中使用 AUGraph 在 AudioUnit 中播放立体声答案

【问题标题】：Play stereo sound in AudioUnit using AUGraph in IOS在 IOS 中使用 AUGraph 在 AudioUnit 中播放立体声
【发布时间】：2021-09-17 18:18:09
【问题描述】：

我想在 ios 中使用 AUGraph 使用 Audiounit 播放立体声，但我面临的问题是“当我想以 48000 采样率在立体声模式下播放时，我的声音播放速度很快”。但它适用于单声道声音（单声道）。

这是我的代码。

import Combine
import AudioUnit
import Foundation
import AudioToolbox
import AVFoundation

@objc protocol AudioUnitDataChannelPlayoutDelegate
{
    func performInput(
        _ ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>,
        inTimeStamp: UnsafePointer<AudioTimeStamp>,
        inBufNumber: UInt32,
        inNumberFrames: UInt32,
        ioData: UnsafeMutablePointer<AudioBufferList> ) -> OSStatus
}

private let AudioController_InputCallback: AURenderCallback =
{
    (
        inRefCon,
        ioActionFlags,
        inTimeStamp,
        inBufNumber,
        inNumberFrames,
        ioData
    )-> OSStatus in
    
    let delegate = unsafeBitCast(inRefCon, to: AudioUnitDataChannelPlayoutDelegate.self)
    
    let result = delegate.performInput(ioActionFlags,
                                       inTimeStamp: inTimeStamp,
                                       inBufNumber: inBufNumber,
                                       inNumberFrames: inNumberFrames,
                                       ioData: ioData!)
    return noErr
}

class AudioUnitDataChannelPlayout
{
    
    private static var instance: AudioUnitDataChannelPlayout?
    
    public class var sharedInstance: AudioUnitDataChannelPlayout
    {
        if instance == nil
        {
            instance = AudioUnitDataChannelPlayout()
        }
        return instance!
    }
    
    static let audioBuffer = CircularBuffer(size: 25003904)
   
    let kInputBus: UInt32 = 1
    let kOutputBus: UInt32 = 0
    var status: OSStatus?
    var flag: UInt32 = 1
    
    var ioFormat = CAStreamBasicDescription(
        sampleRate: Double(48000.0),
        numChannels: 2,
        pcmf: .int16,
        isInterleaved: true )
    
    var timePitchFormat = CAStreamBasicDescription(
        sampleRate: Double(48000.0),
        numChannels: 1,  // if chnges to 2 nothing happens
        pcmf: .float32,
        isInterleaved: false ) // if change to true then error occurs
    
    var graph: AUGraph?
    var firstConverterNode: AUNode = 0
    var timePitchNode: AUNode = 0
    var secondConverterNode: AUNode = 0
    var outputNode: AUNode = 0
    var firstConverterUnit: AudioUnit?
    var timePitchUnit: AudioUnit?
    var secondConverterUnit: AudioUnit?
    var outputUnit: AudioUnit?
    
    
    init()
    {
        configureAudioSession()
        setupRecordingUnit()
        playAudio()
    }
    
    private func setupRecordingUnit()
    {
        check(error: NewAUGraph(&graph), description: "Failed to create AUGraph")
        
        var output_desc = AudioComponentDescription(
            componentType: OSType(kAudioUnitType_Output),
            componentSubType: OSType(kAudioUnitSubType_VoiceProcessingIO),
            componentManufacturer: OSType(kAudioUnitManufacturer_Apple),
            componentFlags: 0,
            componentFlagsMask: 0 )
        
        var converter_desc = AudioComponentDescription(
            componentType: OSType(kAudioUnitType_FormatConverter),
            componentSubType: OSType(kAudioUnitSubType_AUConverter),
            componentManufacturer: OSType(kAudioUnitManufacturer_Apple),
            componentFlags: 0,
            componentFlagsMask: 0 )
        
        var varispeed_desc = AudioComponentDescription(
            componentType: OSType(kAudioUnitType_FormatConverter),
            componentSubType: OSType(kAudioUnitSubType_NewTimePitch),
            componentManufacturer: OSType(kAudioUnitManufacturer_Apple),
            componentFlags: 0,
            componentFlagsMask: 0 )
        
        check(error: AUGraphAddNode(graph!, &output_desc, &outputNode), description: "Failed to Add Node Audio Node")
        
        check(error: AUGraphAddNode(graph!, &converter_desc, &firstConverterNode), description: "Failed to Add converter node")
        check(error: AUGraphAddNode(graph!, &varispeed_desc, &timePitchNode), description: "Failed to Add Node varispeed Node")
        check(error: AUGraphAddNode(graph!, &converter_desc, &secondConverterNode), description: "Failed to Add converter node")
        
        check(error: AUGraphOpen(graph!), description: "Failed to open AUGraph")
        
        check(error: AUGraphNodeInfo(graph!, outputNode, nil, &outputUnit), description: "Failed to get Info of audioUnit")
        check(error: AUGraphNodeInfo(graph!, firstConverterNode, nil, &firstConverterUnit), description: "Failed to get Info of converterUnit")
        check(error: AUGraphNodeInfo(graph!, timePitchNode, nil, &timePitchUnit), description: "Failed to get Info of VarispeedUnit")
        check(error: AUGraphNodeInfo(graph!, secondConverterNode, nil, &secondConverterUnit), description: "Failed to get Info of converterUnit")
        
        check(error: AudioUnitSetProperty(outputUnit!,kAudioOutputUnitProperty_EnableIO,kAudioUnitScope_Output,kOutputBus,&flag,MemoryLayoutStride.SizeOf32(flag)),
              description: "Failed to set enable IO for Playing.")
        
        check(error: AudioUnitSetProperty(firstConverterUnit!, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, kOutputBus, &ioFormat, MemoryLayoutStride.SizeOf32(ioFormat)), description: "Failed to set property of firstConverter Unit")
        
        check(error: AudioUnitSetProperty(firstConverterUnit!, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, kOutputBus, &timePitchFormat, MemoryLayoutStride.SizeOf32(timePitchFormat)), description: "Failed to set property of firstConverter Unit 1")
        
        check(error: AudioUnitSetProperty(timePitchUnit!, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, kOutputBus, &timePitchFormat, MemoryLayoutStride.SizeOf32(timePitchFormat)), description: "Failed to set property of varispeed unit")
        
        check(error: AudioUnitSetProperty(timePitchUnit!, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, kOutputBus, &timePitchFormat, MemoryLayoutStride.SizeOf32(timePitchFormat)), description: "Failed to set property of Varispeed Unit 1")
        
        check(error: AudioUnitSetProperty(secondConverterUnit!, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, kOutputBus, &timePitchFormat, MemoryLayoutStride.SizeOf32(timePitchFormat)), description: "Failed to set property of firstConverter Unit")
        
        check(error: AudioUnitSetProperty(secondConverterUnit!, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, kOutputBus, &ioFormat, MemoryLayoutStride.SizeOf32(ioFormat)), description: "Failed to set property of firstConverter Unit 1")
        
        
        check(error: AudioUnitSetProperty(outputUnit!, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, kOutputBus, &ioFormat, MemoryLayoutStride.SizeOf32(ioFormat)), description: "Failed to set property of Output Unit")
        AUGraphConnectNodeInput(graph!, firstConverterNode, 0, timePitchNode, 0)
        AUGraphConnectNodeInput(graph!, timePitchNode, 0, secondConverterNode, 0)
        AUGraphConnectNodeInput(graph!, secondConverterNode, 0, outputNode, 0)
        
        
        var recordingCallback = AURenderCallbackStruct(
            inputProc: AudioController_InputCallback,
            inputProcRefCon: UnsafeMutableRawPointer(Unmanaged.passUnretained(self).toOpaque()) )
        
        check(error: AUGraphSetNodeInputCallback(graph!, firstConverterNode, 0, &recordingCallback), description: "Failed to set inPutCallback")
        
        AUGraphInitialize(graph!)
    }
    
    func check(error: OSStatus, description: String)
    {
        if error != noErr
        {
            fatalError("\(description) : \(error)")
        }
    }
    
    func startSpeakerUnit()
    {
        check(error: AUGraphStart(graph!), description: "Error Failed to start AUGraph")
        print("initializing the speaker unit")
    }
    
    func stopSpeakerUnit()
    {
        check(error: AUGraphStop(graph!), description: "Error Failed to stop AUGraph")
        AudioUnitDataChannelPlayout.instance = nil
    }

    private func playAudio()
    {
        AudioUnitSetParameter(self.timePitchUnit!, kNewTimePitchParam_Rate, kAudioUnitScope_Global,0, AudioUnitParameterValue(1.0), 0)
    }
    
}

extension AudioUnitDataChannelPlayout: AudioUnitDataChannelPlayoutDelegate
{
    func performInput(_ ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>, inTimeStamp: UnsafePointer<AudioTimeStamp>, inBufNumber: UInt32, inNumberFrames: UInt32, ioData: UnsafeMutablePointer<AudioBufferList>) -> OSStatus
    {
        
        let playbackPointer = ioData[0].mBuffers
        
        print("SECOND POINTER: \(playbackPointer)")

        let bytesToCopy = ioData[0].mBuffers.mDataByteSize

        
        var bufferTail = AudioUnitDataChannelPlayout.audioBuffer.getTail()
        
        print(AudioUnitDataChannelPlayout.audioBuffer.getAvailableBytes())

        let bytesToWrite = min(bytesToCopy, AudioUnitDataChannelPlayout.audioBuffer.getAvailableBytes())
        
        memcpy(playbackPointer.mData, bufferTail, Int(bytesToWrite))
        
        print("playing...\(bytesToCopy)")
        AudioUnitDataChannelPlayout.audioBuffer.consume(samples: bytesToWrite)
        
        return noErr
    }
    
}

在这堂课中，我只是在播放立体声的波形文件。在这方面的任何帮助将不胜感激。

【问题讨论】：

播放速度真的更快吗？还是音高变了？或两者？所有立体声源都会发生这种情况吗？请提供有关此问题的更多详细信息，以便我们猜测可能是什么原因。
是的，所有立体声源都会发生这种情况，而且播放速度也非常快，我不确定它的音高是否发生了变化。这是从augraph drive.google.com/drive/folders/…传递之前和之后的wave文件的链接最后但并非最不重要的是非常感谢您的关注。
我不知道您的代码，但在耳朵看来，这听起来像是应用了 2x 速度效果，但没有校正由此产生的音高变化。要么您在不知情的情况下在立体声链中产生了这种效果，要么您可能遇到输入和输出之间的值不匹配等问题。
我看到你的代码中有一个timePitchNode。这可能是问题的根源（无论如何我都会开始调试，然后再做任何其他事情）。例如，完全停用此效果，看看您的导出是否仍然有问题。
对于第一部分，我浏览了所有代码并尝试发现是否应用了速度效果，但我没有得到它。我只是在播放器中提供原始 .wav 文件，我认为它的输入和输出是相同的。对于第二部分，timepitchNode 可以很好地处理单声道声音，但我会按照你说的那样尝试。

标签： ios swift audiounit playing augraph

【解决方案1】：

上面写的我的播放器代码没有错误。但是以快速模式播放音频的主要原因是，在将数据插入播放器时，我提供了立体声数据，但将其视为单声道（因为我只填充了一半的帧数）。在分配内存时，我将帧数与通道数相乘，结果成功了。

【讨论】：