ios - 音频队列 : AudioQueueStart returns -50

Question

我正在尝试在 GLES 应用程序 (Unity3d) 中编写麦克风功率计模块。它在 UIKit 应用程序中运行良好。但是当我集成到我的unity3d项目中时，AudioQueue无法启动属性。调用AudioQueueStart的结果代码总是-50，但-50是什么意思？我在 iOS Developer Library 中找不到引用。

我搜索过这个问题，知道有人在 cocos2d 应用程序中有同样的问题。也许这有一些相关性。

这是我启动音频队列的代码:

UInt32 ioDataSize = sizeof(sampleRate);
AudioSessionGetProperty(kAudioSessionProperty_CurrentHardwareSampleRate, &ioDataSize, &sampleRate); //returns noErr
format.mSampleRate = sampleRate;
format.mFormatID = kAudioFormatLinearPCM;
format.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
format.mFramesPerPacket = format.mChannelsPerFrame = 1;
format.mBitsPerChannel = 16;
format.mBytesPerPacket = format.mBytesPerFrame = 2;

AudioQueueNewInput(&format, listeningCallback, self, NULL, NULL, 0, &queue); //returns noErr

AudioQueueBufferRef buffers[3];
for (NSInteger i = 0; i < 3; ++i) { 
    AudioQueueAllocateBuffer(queue, 735, &buffers[i]); //returns noErr
    AudioQueueEnqueueBuffer(queue, buffers[i], 0, NULL); //returns noErr
}

levels = (AudioQueueLevelMeterState *)calloc(sizeof(AudioQueueLevelMeterState), format.mChannelsPerFrame);
UInt32 trueValue = true;
AudioQueueSetProperty(queue, kAudioQueueProperty_EnableLevelMetering, &trueValue, sizeof(UInt32)); //returns noErr

AudioQueueStart(queue, NULL); //returns -50

Answer 1

以下对我有用:

添加这个:

AVAudioSession * session = [AVAudioSession sharedInstance];

    if (!session) printf("ERROR INITIALIZING AUDIO SESSION! \n");
    else{


        [session setCategory:AVAudioSessionCategoryPlayAndRecord error:&nsError];

        if (nsError) printf("couldn't set audio category!");



        [session setActive:YES error:&nsError];
        if (nsError) printf("AudioSession setActive = YES failed");
    }

在 AudioQueueStart(myQueue, NULL); 之前