Question

我有以下代码块，应该创建一个产生正弦波的AVAudioNode，但它会在标有 - [AUAudioUnitV2Bridge setOutputProvider：]的行上崩溃：无法识别的选择器发送到实例。< / p>

任何想法可能出错？

// TEST  
AudioComponentDescription mixerDesc;  
mixerDesc.componentType = kAudioUnitType_Generator;  
mixerDesc.componentSubType = kAudioUnitSubType_ScheduledSoundPlayer;  
mixerDesc.componentManufacturer = kAudioUnitManufacturer_Apple;  
mixerDesc.componentFlags = 0;  
mixerDesc.componentFlagsMask = 0;  

[AVAudioUnit instantiateWithComponentDescription:mixerDesc options:kAudioComponentInstantiation_LoadInProcess completionHandler:^(__kindof AVAudioUnit * _Nullable audioUnit, NSError * _Nullable error) {  
    NSLog(@"here");  

    // Crashes here  
    audioUnit.AUAudioUnit.outputProvider = ^AUAudioUnitStatus(AudioUnitRenderActionFlags *actionFlags, const AudioTimeStamp *timestamp, AUAudioFrameCount frameCount, NSInteger inputBusNumber, AudioBufferList *inputData)  
    {  
        const double amplitude = 0.2;  
        static double theta = 0.0;  
        double theta_increment = 2.0 * M_PI * 880.0 / 44100.0;  
        const int channel = 0;  
        Float32 *buffer = (Float32 *)inputData->mBuffers[channel].mData;  

        memset(inputData->mBuffers[channel].mData, 0, inputData->mBuffers[channel].mDataByteSize);  
        memset(inputData->mBuffers[1].mData, 0, inputData->mBuffers[1].mDataByteSize);  

        // Generate the samples  
        for (UInt32 frame = 0; frame < inputBusNumber; frame++)  
        {  
            buffer[frame] = sin(theta) * amplitude;  

            theta += theta_increment;  
            if (theta >= 2.0 * M_PI)  
            {  
                theta -= 2.0 * M_PI;  
            }  
        }  

        return noErr;  
    };  

}];

更新

感觉像这样的东西是正确的方法，但唉，状态抛出错误，回调从未调用。：

    AVAudioUnitGenerator *unit = [[AVAudioUnitGenerator alloc] init];

// TEST
AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Generator;
desc.componentSubType = kAudioUnitSubType_ScheduledSoundPlayer;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;

[AVAudioUnit instantiateWithComponentDescription:desc options:kAudioComponentInstantiation_LoadInProcess completionHandler:^(__kindof AVAudioUnit * _Nullable audioUnit, NSError * _Nullable error) {
    NSLog(@"here");

    self.audioNode = audioUnit;

    OSStatus status;
     AudioUnit *unit = audioUnit.audioUnit;

    UInt32 numBuses = 1;
    status = AudioUnitSetProperty(unit, kAudioUnitProperty_ElementCount, kAudioUnitScope_Output, 0, &numBuses, sizeof(UInt32));
    NSLog(@"status: %d", status);


    AURenderCallbackStruct rcbs;
    rcbs.inputProc = callback2;
    rcbs.inputProcRefCon = (__bridge void * _Nullable)(self);


    status = AudioUnitSetProperty(unit, kAudioUnitProperty_SetRenderCallback, kAudioUnitScope_Output, 0, &rcbs, sizeof(rcbs));
    NSLog(@"status: %d", status);

}];

Answer 1

错误消息的确切含义。在实例化您请求的audioUnit类型并确保AUAudioUnit不是nil之后，此代码使其明确：

if (![audioUnit.AUAudioUnit respondsToSelector:@selector(outputProvider)]) {
        NSLog(@"selector method not found in this instance of an AUAudioUnit");
}

头文件并未声称绝对需要在所有音频单元中实现此方法。

稍后添加：如果您只想让代码合成AVAudioUnit的样本，并且不关心特定的API或代码结构，那么：获取AVAudioUnit实例的AudioUnit属性;创建AURenderCallback函数;使用此C函数填写AURenderCallbackStruct;然后在AudioUnit上为kAudioUnitProperty_SetRenderCallback做一个AudioUnitSetProperty。即使没有outputProvider方法可用，这似乎也不会崩溃。

带有AVAudioEngine的自定义AVAudioUnit在set provider block

1 个答案: