从Springboard返回后导致通用跳过的AudioUnit [英] AudioUnits causing universal skipping after returning from Springboard

问题描述

我在使用AudioUnits的应用程序中遇到问题。所有应用程序音频（包括未通过AudioUnits播放的音频）将在退出Springboard并返回应用程序后开始跳过。

I have a problem in my applications where I am using AudioUnits. All of the applications Audio (including audio not played through AudioUnits) will start skipping after exiting to Springboard and returning to the applications.

我将问题分解为一个新的单独的测试应用。以下是重复步骤：

I broke out the problem into a new separate test app. Here are the steps to repeat it:

• 使用
  AVAudioPlayer播放音频文件。


• 创建，删除，然后再创建一个
  AudioUnit


• 退出到跳板


• 返回应用


• 来自AvAudioPlayer的音频将开始跳过

• Start an Audio file playing using an AVAudioPlayer.
• Create, Delete, then again Create an AudioUnit
• Exit to Springboard
• Return to the app
• The Audio from the AvAudioPlayer will start skipping

以下是我使用的一些代码：

Here is some of the code I used:

- (IBAction)restartAudioUnit {

    MySoundStream* audioUnitClass;
    audioUnitClass = Load();
    [audioUnitClass release];
    audioUnitClass = Load();

}

原谅长代码转储，但AudioUnits很复杂，我是相当肯定我只是设置它们或者错误地将它们取下来。

Forgive the long code dump but AudioUnits are complex and I am fairly sure I am just setting them up or taking them down incorrectly.

MySoundStream类：

The MySoundStream class:

OSStatus UnitRenderCB(void* pRefCon, AudioUnitRenderActionFlags* flags, const AudioTimeStamp* timeStamp, UInt32 busNum, UInt32 numFrames, AudioBufferList*  pData){

    OSStatus tErr = noErr;

    //Do Nothing

    return tErr;
}

@implementation MySoundStream

-(void) dealloc {

    [self Unload];

    [super dealloc];
}

-(void) Unload {

    OSStatus tErr = noErr; 
    tErr = AudioUnitUninitialize(OutUnit);
}

@end

MySoundStream* Load()
{
    OSStatus tErr = noErr;
    AudioComponentInstance tRIO;
    AudioComponentDescription tRIOCD;
    AURenderCallbackStruct tRIOCB;
    AudioStreamBasicDescription tAUF;

    tRIOCD.componentType = kAudioUnitType_Output;
    tRIOCD.componentSubType = kAudioUnitSubType_RemoteIO;
    tRIOCD.componentManufacturer = kAudioUnitManufacturer_Apple;
    tRIOCD.componentFlags = 0;
    tRIOCD.componentFlagsMask = 0;

    AudioComponent tRIOC = AudioComponentFindNext(NULL, &tRIOCD);
    tErr = AudioComponentInstanceNew(tRIOC, &tRIO);
    if (tErr != noErr) return NULL;

    int tOutEnable = 1;

    tErr = AudioUnitSetProperty(tRIO, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Output, 0, &tOutEnable, sizeof(tOutEnable));
    if (tErr != noErr) return NULL; 

    tAUF.mSampleRate = 44100.00;
    tAUF.mFormatID = kAudioFormatLinearPCM;
    tAUF.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
    tAUF.mFramesPerPacket = 1;
    tAUF.mChannelsPerFrame = 2;
    tAUF.mBitsPerChannel = 16;
    tAUF.mBytesPerPacket = 4;
    tAUF.mBytesPerFrame = 4;

    tErr = AudioUnitSetProperty(tRIO, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, 0, &tAUF, sizeof(tAUF));
    if (tErr != noErr) return false;

    MySoundStream* pRet = [MySoundStream alloc];

    tRIOCB.inputProc = UnitRenderCB;
    tRIOCB.inputProcRefCon = pRet;
    tErr = AudioUnitSetProperty(tRIO, kAudioUnitProperty_SetRenderCallback, kAudioUnitScope_Global, 0, &tRIOCB, sizeof(tRIOCB));
    if (tErr != noErr){ delete pRet; return NULL; }

    tErr = AudioUnitInitialize(tRIO);
    if (tErr != noErr){ delete pRet; return NULL; }

    pRet->OutUnit = tRIO;

    return pRet;
}

如果有人能看到任何我在使用这个AudioUnit时出错的话，那就是woudl be非常有帮助。

If anyone can see anything I am doing wrong with this AudioUnit, that woudl be very helpful.

编辑：
上传完整的来源。 此处

1. 按Play Sound（可能需要耳机）


2. 按RestartAudioUnit


3. 返回Springboard


4. 重新输入TestAudioUnit app

1. Press Play Sound (may need headphones)
2. Press RestartAudioUnit
3. Return to Springboard
4. Re-enter TestAudioUnit app

音频将跳过

推荐答案

切换到使用AUGraph来设置我的音频单元路径，我运气更好。

Switched to using an AUGraph to setups my Audio Unit path and I had better luck.

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