Question

我正在iOS中学习AudioUnits并试图实现这样的图表：

    -------------------       -----------------
   |                   |     |                 |
-->|  FormatConverter  | --->| bus 0           |
   |      (Varispeed)  |     |                 |
   --------------------      |    Multichannel |
   --------------------      |    Mixer Unit   |
   |                   |     |                 |      --------------------
-->|  FormatConverter  | --->| bus 1           |     |                    |
   |   (Varispeed)     |     |                 | --->|      Remote IO     | ----->
   --------------------      |                 |     |       Unit         |
   --------------------      |                 |     |                    |
  |                    |     |                 |      --------------------
->| FormatConverter    | --->| bus 2           |
  | (Varispeed)        |     |                 |
  ---------------------      |                 |         
                              -----------------

首先，我尝试使用没有kAudioUnitSubType_Varispeed单元的AudioUnits。它工作正常，声音播放。但现在我想实现每个声音的音高（单独），这就是为什么我决定添加Varispeed单位来控制每个声音的音高。

我正在使用以下代码：

OSStatus result = noErr;

    //............................................................................
    // Specify the audio unit component descriptions for the audio units to be
    //    added to the graph.

    // I/O unit
    AudioComponentDescription iOUnitDescription;
    iOUnitDescription.componentType          = kAudioUnitType_Output;
    iOUnitDescription.componentSubType       = kAudioUnitSubType_RemoteIO;
    iOUnitDescription.componentManufacturer  = kAudioUnitManufacturer_Apple;
    iOUnitDescription.componentFlags         = 0;
    iOUnitDescription.componentFlagsMask     = 0;

    // Multichannel mixer unit
    AudioComponentDescription MixerUnitDescription;
    MixerUnitDescription.componentType          = kAudioUnitType_Mixer;
    MixerUnitDescription.componentSubType       = kAudioUnitSubType_MultiChannelMixer;
    MixerUnitDescription.componentManufacturer  = kAudioUnitManufacturer_Apple;
    MixerUnitDescription.componentFlags         = 0;
    MixerUnitDescription.componentFlagsMask     = 0;

    // Varispeed unit
    AudioComponentDescription varispeedUnitDescription;
    MixerUnitDescription.componentType          = kAudioUnitType_FormatConverter;
    MixerUnitDescription.componentSubType       = kAudioUnitSubType_Varispeed;
    MixerUnitDescription.componentManufacturer  = kAudioUnitManufacturer_Apple;
    MixerUnitDescription.componentFlags         = 0;
    MixerUnitDescription.componentFlagsMask     = 0;

    //............................................................................
    // Add nodes to the audio processing graph.
    NSLog (@"Adding nodes to audio processing graph");

    AUNode iONode;         // node for I/O unit
    AUNode mixerNode;      // node for Multichannel Mixer unit
    AUNode varispeedNode0;
    AUNode varispeedNode1;
    AUNode varispeedNode2;

    //............................................................................
    // Create a new audio processing graph.
    result = NewAUGraph(&processingGraph);

    if (noErr != result) {[self printErrorMessage: @"NewAUGraph" withStatus: result]; return;}

    //............................................................................
    // Open the audio processing graph
    result = AUGraphOpen(processingGraph);

    if (noErr != result) {
        [self printErrorMessage: @"AUGraphOpen" withStatus: result];
        return;
    }

    //............................................................................
    // Add the nodes to the audio processing graph
    result = AUGraphAddNode(
                             processingGraph,
                             &varispeedUnitDescription,
                             &varispeedNode0);

    if (noErr != result) {
        [self printErrorMessage: @"AUGraphNewNode failed for varispeedNode0 unit" withStatus: result];
        return;
    }

    result = AUGraphAddNode (
                             processingGraph,
                             &varispeedUnitDescription,
                             &varispeedNode1);

    if (noErr != result) {
        [self printErrorMessage: @"AUGraphNewNode failed for varispeedNode1 unit" withStatus: result];
        return;
    }

    result = AUGraphAddNode (
                             processingGraph,
                             &varispeedUnitDescription,
                             &varispeedNode2);

    if (noErr != result) {
        [self printErrorMessage: @"AUGraphNewNode failed for varispeedNode2 unit" withStatus: result];
        return;
    }

    result = AUGraphAddNode (
                             processingGraph,
                             &iOUnitDescription,
                             &iONode);

    if (noErr != result) {
        [self printErrorMessage: @"AUGraphNewNode failed for I/O unit" withStatus: result];
        return;
    }

    result = AUGraphAddNode (
                             processingGraph,
                             &MixerUnitDescription,
                             &mixerNode);

    if (noErr != result) {
        [self printErrorMessage: @"AUGraphNewNode failed for Mixer unit" withStatus: result];
        return;
    }

当我运行app时，我遇到以下错误：

2013-04-24 21:44:59.335 Drumpads[327:c07] *** AUGraphNewNode failed for varispeedNode0 unit error: ˇˇ¯+
2013-04-24 21:44:59.338 Drumpads[327:c07] Error.domain = NSOSStatusErrorDomain, code=-2005, descr =Error Domain=NSOSStatusErrorDomain Code=-2005 "The operation couldn’t be completed. (OSStatus error -2005.)"

根据MacErrors.h -2005表示'badComponentType'。

所以似乎Varispeed Unit甚至无法添加到AUGraph。一切似乎都是正确的，所以我不知道为什么添加Varispeed节点会导致错误。

我使用sample code from developers.apple.com代码作为参考（我知道，它适用于OSx，但Varispeed现在可用于iOS5和6，因此我决定可以使用此代码作为参考）。

我需要控制每个声音的音高变化。我选择了Varispeed，但我也读过NewTimePitch Nodes。我尝试过NewTimePitch（在同一图表中），但也没有成功。

有人知道我的代码有什么问题吗？为什么添加Varispeed Node会导致错误？

提前致谢！

Answer 1

经过一天的研究并试图找到有关FormatConverter和Varispeed的更多信息并阅读大量信息后，我终于找到了答案。

当然很难解决它，但幸运的是我！ LOL

这是我以前的代码：

AudioComponentDescription varispeedUnitDescription;
MixerUnitDescription.componentType          = kAudioUnitType_FormatConverter;
MixerUnitDescription.componentSubType       = kAudioUnitSubType_Varispeed;
MixerUnitDescription.componentManufacturer  = kAudioUnitManufacturer_Apple;
MixerUnitDescription.componentFlags         = 0;
MixerUnitDescription.componentFlagsMask     = 0;

这是新的：

AudioComponentDescription varispeedUnitDescription;
varispeedUnitDescription.componentType          = kAudioUnitType_FormatConverter;
varispeedUnitDescription.componentSubType       = kAudioUnitSubType_Varispeed;
varispeedUnitDescription.componentManufacturer  = kAudioUnitManufacturer_Apple;
varispeedUnitDescription.componentFlags         = 0;
varispeedUnitDescription.componentFlagsMask     = 0;

所以...这是非常糟糕的组件类型（-2005），因为varispeedUnitDescription实际上没有被正确描述。

如何将kAudio UnitSubType_Varispeed音频单元添加到iOS 6中的A Graph

1 个答案: