ios - 停止 AudioUnit 录制后出错
<p><p>我正在尝试使用以下代码从 iPhone 的麦克风中获取音频输入:</p>
<pre><code>@property (nonatomic) AudioUnit rioUnit;
@property (nonatomic) CAStreamBasicDescription outputCASBD;
(...)
// set our required format - LPCM non-interleaved 32 bit floating point
CAStreamBasicDescription outFormat = CAStreamBasicDescription(44100, // sample rate
kAudioFormatLinearPCM, // format id
4, // bytes per packet
1, // frames per packet
4, // bytes per frame
1, // channels per frame
32, // bits per channel
kAudioFormatFlagIsFloat | kAudioFormatFlagIsNonInterleaved);
try {
// Open the output unit
AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Output;
desc.componentSubType = kAudioUnitSubType_RemoteIO;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;
AudioComponent comp = AudioComponentFindNext(NULL, &desc);
AudioComponentInstanceNew(comp, &_rioUnit);
UInt32 one = 1;
XThrowIfError(AudioUnitSetProperty(_rioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Input, 1, &one, sizeof(one)), "couldn't enable input on the remote I/O unit");
AURenderCallbackStruct callbackStruct;
callbackStruct.inputProc = renderInput;
callbackStruct.inputProcRefCon = (__bridge void*)self;
XThrowIfError(AudioUnitSetProperty(_rioUnit, kAudioOutputUnitProperty_SetInputCallback, kAudioUnitScope_Global, 0, &callbackStruct, sizeof(callbackStruct)), "couldn't set remote i/o render callback");
XThrowIfError(AudioUnitSetProperty(_rioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, 0, &outFormat, sizeof(outFormat)), "couldn't set the remote I/O unit's output client format");
XThrowIfError(AudioUnitSetProperty(_rioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 1, &outFormat, sizeof(outFormat)), "couldn't set the remote I/O unit's input client format");
XThrowIfError(AudioUnitInitialize(_rioUnit), "couldn't initialize the remote I/O unit");
XThrowIfError(AudioOutputUnitStart(_rioUnit), "couldn't start the remote I/O unit");
}
catch (CAXException &e) {
char buf;
fprintf(stderr, "Error: %s (%s)\n", e.mOperation, e.FormatError(buf));
}
catch (...) {
fprintf(stderr, "An unknown error occurred\n");
}
// Allocate our own buffers (1 channel, 16 bits per sample, thus 16 bits per frame, thus 2 bytes per frame).
// Practice learns the buffers used contain 512 frames, if this changes it will be fixed in processAudio.
// will need float for accellerate fft (input is 16 bit signed integer) so make space...
_tempBuffer.mNumberChannels = outFormat.mChannelsPerFrame;
_tempBuffer.mDataByteSize = 512 * outFormat.mBytesPerFrame * 2;
_tempBuffer.mData = malloc( self.tempBuffer.mDataByteSize );
</code></pre>
<p>一切都很好，直到我想停止收听麦克风输入。</p>
<p>我正在这样做:</p>
<pre><code> AudioOutputUnitStop(_rioUnit);
AudioUnitUninitialize(_rioUnit);
AudioComponentInstanceDispose(_rioUnit);
_rioUnit = nil;
</code></pre>
<p>但我从为 <code>kAudioOutputUnitProperty_SetInputCallback</code> 定义的回调函数内部得到一个错误。</p>
<p>错误是:<code>AURemoteIO::IOThread (14): EXC_BAD_ACCESS (code=1, address=0x8000000c)</code> </p>
<p>在我看来，AudioUnit 的 InputCallback 仍在被调用，即使我正在停止它、对其实例进行统一化和处置。</p>
<p>为什么会发生这种情况？如何防止 InputCallback 在我停止、统一化和处置其实例后被调用？</p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>首先，确保 _rioUnit 在 stop 和 start 中确实具有相同的值。</p>
<p>正在另一个异步线程中调用音频输入回调。因此，在取消初始化或处置音频单元或任何其他所需的数据结构之前，您可能需要等到该线程也停止(这通常发生在少于 2 个音频缓冲区持续时间的时间内，因此这可能是一个合理的等待时间) .</p></p>
<p style="font-size: 20px;">关于ios - 停止 AudioUnit 录制后出错，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/27219182/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/27219182/
</a>
</p>
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