iphone - AUGraphInitialize 将kAudioUnitSubType_Reverb2 添加到AUGraph 时出现错误代码-10868

Question

我正在尝试将类型为 kAudioUnitSubType_Reverb2 的 AudioUnit 添加到 AUGraph 并在AUGraphInitialize。我的出发点是 Apple 的 iPhoneMixerEQGraphTest 示例应用程序，我基本上只是为混响添加了一个新的 AudioUnit，但无法让它工作。

这是代码-

- (void)initializeAUGraph
{
    printf("initializeAUGraph\n");

    AUNode outputNode;
    AUNode eqNode;
    AUNode mixerNode;
    AUNode reverbNode;

    printf("create client ASBD\n");

    // client format audio goes into the mixer
    mClientFormat.SetCanonical(2, true);                        
    mClientFormat.mSampleRate = kGraphSampleRate;
    mClientFormat.Print();

    printf("create output ASBD\n");

    // output format
    mOutputFormat.SetAUCanonical(2, false);                     
    mOutputFormat.mSampleRate = kGraphSampleRate;
    mOutputFormat.Print();

    OSStatus result = noErr;

    // load up the audio data
    [self performSelectorInBackground:@selector(loadFiles) withObject:nil];

    printf("new AUGraph\n");

    // create a new AUGraph
    result = NewAUGraph(&mGraph);
    if (result) { printf("NewAUGraph result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

    // create three CAComponentDescription for the AUs we want in the graph

    // output unit
    CAComponentDescription output_desc(kAudioUnitType_Output, kAudioUnitSubType_RemoteIO, kAudioUnitManufacturer_Apple);

    // iPodEQ unit
    CAComponentDescription eq_desc(kAudioUnitType_Effect, kAudioUnitSubType_AUiPodEQ, kAudioUnitManufacturer_Apple);

    // multichannel mixer unit
    CAComponentDescription mixer_desc(kAudioUnitType_Mixer, kAudioUnitSubType_MultiChannelMixer, kAudioUnitManufacturer_Apple);

    // reverb unit
    CAComponentDescription reverb_desc(kAudioUnitType_Effect, kAudioUnitSubType_Reverb2, kAudioUnitManufacturer_Apple);

    printf("add nodes\n");

    // create a node in the graph that is an AudioUnit, using the supplied AudioComponentDescription to find and open that unit
    result = AUGraphAddNode(mGraph, &output_desc, &outputNode);
    if (result) { printf("AUGraphNewNode 1 result %lu %4.4s\n", result, (char*)&result); return; }

    result = AUGraphAddNode(mGraph, &eq_desc, &eqNode);
    if (result) { printf("AUGraphNewNode 2 result %lu %4.4s\n", result, (char*)&result); return; }

    result = AUGraphAddNode(mGraph, &mixer_desc, &mixerNode);
    if (result) { printf("AUGraphNewNode 3 result %lu %4.4s\n", result, (char*)&result); return; }

    result = AUGraphAddNode(mGraph, &reverb_desc, &reverbNode);
    if (result) { printf("AUGraphNewNode 4 result %lu %4.4s\n", result, (char*)&result); return; }

    // connect a node's output to a node's input
    // mixer -> eq -> output
    result = AUGraphConnectNodeInput(mGraph, mixerNode, 0, eqNode, 0);
    if (result) { printf("AUGraphConnectNodeInput result %lu %4.4s\n", result, (char*)&result); return; }

    result = AUGraphConnectNodeInput(mGraph, eqNode, 0, reverbNode, 0);
    if (result) { printf("AUGraphConnectNodeInput result %lu %4.4s\n", result, (char*)&result); return; }

    result = AUGraphConnectNodeInput(mGraph, reverbNode, 0, outputNode, 0);
    if (result) { printf("AUGraphConnectNodeInput reverb result %lu %4.4s\n", result, (char*)&result); return; }

    // open the graph AudioUnits are open but not initialized (no resource allocation occurs here)
    result = AUGraphOpen(mGraph);
    if (result) { printf("AUGraphOpen result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

    // grab the audio unit instances from the nodes
    result = AUGraphNodeInfo(mGraph, mixerNode, NULL, &mMixer);
    if (result) { printf("AUGraphNodeInfo result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

    result = AUGraphNodeInfo(mGraph, eqNode, NULL, &mEQ);
    if (result) { printf("AUGraphNodeInfo result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

    result = AUGraphNodeInfo(mGraph, reverbNode, NULL, &mReverb);
    if (result) { printf("AUGraphNodeInfo reverb result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

    // set bus count
    UInt32 numbuses = 2;

    printf("set input bus count %lu\n", numbuses);

    result = AudioUnitSetProperty(mMixer, kAudioUnitProperty_ElementCount, kAudioUnitScope_Input, 0, &numbuses, sizeof(numbuses));
    if (result) { printf("AudioUnitSetProperty result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

    for (int i = 0; i < numbuses; ++i) {
        // setup render callback struct
        AURenderCallbackStruct rcbs;
        rcbs.inputProc = &renderInput;
        rcbs.inputProcRefCon = &mUserData;

        printf("set AUGraphSetNodeInputCallback\n");

        // set a callback for the specified node's specified input
        result = AUGraphSetNodeInputCallback(mGraph, mixerNode, i, &rcbs);
        if (result) { printf("AUGraphSetNodeInputCallback result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

        printf("set input bus %d, client kAudioUnitProperty_StreamFormat\n", i);

        // set the input stream format, this is the format of the audio for mixer input
        result = AudioUnitSetProperty(mMixer, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, i, &mClientFormat, sizeof(mClientFormat));
        if (result) { printf("AudioUnitSetProperty result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }
    }

    printf("get EQ kAudioUnitProperty_FactoryPresets\n");

    // get the eq's factory preset list -- this is a read-only CFArray array of AUPreset structures
    // host owns the retuned array and should release it when no longer needed
    UInt32 size = sizeof(mEQPresetsArray);
    result = AudioUnitGetProperty(mEQ, kAudioUnitProperty_FactoryPresets, kAudioUnitScope_Global, 0, &mEQPresetsArray, &size);
    if (result) { printf("AudioUnitGetProperty result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

    /* this code can be used if you're interested in dumping out the preset list
    printf("iPodEQ Factory Preset List:\n");
    UInt8 count = CFArrayGetCount(mEQPresetsArray);
    for (int i = 0; i < count; ++i) {
        AUPreset *aPreset = (AUPreset*)CFArrayGetValueAtIndex(mEQPresetsArray, i);
        CFShow(aPreset->presetName);
    }*/

    printf("set output kAudioUnitProperty_StreamFormat\n");

    // set the output stream format of the mixer
    result = AudioUnitSetProperty(mMixer, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 0, &mOutputFormat, sizeof(mOutputFormat));
    if (result) { printf("AudioUnitSetProperty result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

    printf("set render notification\n");

    // add a render notification, this is a callback that the graph will call every time the graph renders
    // the callback will be called once before the graph’s render operation, and once after the render operation is complete
    result = AUGraphAddRenderNotify(mGraph, renderNotification, &mUserData);
    if (result) { printf("AUGraphAddRenderNotify result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

    printf("AUGraphInitialize\n");

    // now that we've set everything up we can initialize the graph, this will also validate the connections
    result = AUGraphInitialize(mGraph);
    if (result) { printf("AUGraphInitialize result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }
    // ---- result here is error code 10868

    CAShow(mGraph);
}

Answer 1

由于某些原因，一些 AU 节点默认采用 float 格式的流格式，而其他节点则采用整数格式。如果流格式不匹配，则会出现此错误。所以你需要在你的均衡器节点和你的混响节点之间添加一个格式转换器:

    AudioComponentDescription convertUnitDescription;
convertUnitDescription.componentManufacturer  = kAudioUnitManufacturer_Apple;
convertUnitDescription.componentType          = kAudioUnitType_FormatConverter;
convertUnitDescription.componentSubType       = kAudioUnitSubType_AUConverter;
convertUnitDescription.componentFlags         = 0;
convertUnitDescription.componentFlagsMask     = 0;
result = AUGraphAddNode (graph, &convertUnitDescription, &convertNode);
NSCAssert (result == noErr, @"Unable to add the converted unit to the audio processing graph. Error code: %d '%.4s'", (int) result, (const char *)&result);

确保将转换器节点输入的流格式设置为均衡器节点输出的格式:

    AudioStreamBasicDescription eqStreamFormat;
UInt32 streamFormatSize = sizeof(eqStreamFormat);
result = AudioUnitGetProperty(eqUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 0, &eqStreamFormat, &streamFormatSize);
NSAssert (result == noErr, @"Unable to get eq output format. Error code: %d '%.4s'", (int) result, (const char *)&result);

result = AudioUnitSetProperty(convertUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, 0, &eqStreamFormat, streamFormatSize);
NSAssert (result == noErr, @"Unable to set converter input format. Error code: %d '%.4s'", (int) result, (const char *)&result);

对转换器的输出做同样的事情，用混响的输入格式设置它。这应该会使您的图表初始化并运行，但如果您设法让混响节点实际执行某些操作，请告诉我，因为它对我不起作用。