在 Spotify iOS SDK 中混合两个 AUNode

Question

我正在尝试使用动态处理器和一堆过滤器来压缩 spotify 方法中的特定频带 connectOutputBus 但是当我在 kAudioUnitSubType_MultiChannelMixer 中混合节点时只有声音第一个添加的节点出来。

obs：我实际上在 sourceNodeCopy 上使用过滤器来删除将在 souceNode 上压缩的频率，但为了简短起见，我省略了它们。

代码如下：

override func connectOutputBus(_ sourceOutputBusNumber: UInt32, ofNode  sourceNode: AUNode, toInputBus destinationInputBusNumber: UInt32, ofNode destinationNode: AUNode, in graph: AUGraph!) throws {

  let sourceNodeCopy = sourceNode //original node without the harsh freq

  //create a filter for the harsh frequencies
  var filterDescription = AudioComponentDescription()
  filterDescription.componentType = kAudioUnitType_Effect
  filterDescription.componentSubType = kAudioUnitSubType_BandPassFilter
  filterDescription.componentManufacturer = kAudioUnitManufacturer_Apple
  filterDescription.componentFlags = 0
  filterDescription.componentFlagsMask = 0

  AUGraphAddNode(graph, &filterDescription, &filterNode!) // Add the filter node
  AUGraphNodeInfo(graph, filterNode!, nil, &filterUnit!) // Get the Audio Unit from the node
  AudioUnitInitialize(filterUnit!) // Initialize the audio unit
  // Set filter params
  AudioUnitSetParameter(filterUnit!, kBandpassParam_CenterFrequency, kAudioUnitScope_Global, 0, 10038, 0)

  //create a processor to compress the frequency
  var dynamicProcessorDescription = AudioComponentDescription()
  dynamicProcessorDescription.componentType = kAudioUnitType_Effect
  dynamicProcessorDescription.componentSubType = kAudioUnitSubType_DynamicsProcessor
  dynamicProcessorDescription.componentManufacturer = kAudioUnitManufacturer_Apple
  dynamicProcessorDescription.componentFlags = 0
  dynamicProcessorDescription.componentFlagsMask = 0

  // Add the dynamic processor node
  AUGraphAddNode(graph, &dynamicProcessorDescription, &dynamicProcessorNode)
  AUGraphNodeInfo(graph, dynamicProcessorNode, nil, &dynamicProcessorUnit)
  AudioUnitInitialize(dynamicProcessorUnit!)

  // Set compressor params
  AudioUnitSetParameter(dynamicProcessorUnit!, kDynamicsProcessorParam_Threshold, kAudioUnitScope_Global, 0, -35, 0)
  AudioUnitSetParameter(dynamicProcessorUnit!, kDynamicsProcessorParam_AttackTime, kAudioUnitScope_Global, 0, 0.02, 0)
  AudioUnitSetParameter(dynamicProcessorUnit!, kDynamicsProcessorParam_ReleaseTime, kAudioUnitScope_Global, 0, 0.04, 0)
  AudioUnitSetParameter(dynamicProcessorUnit!, kDynamicsProcessorParam_HeadRoom, kAudioUnitScope_Global, 0, 0, 0)

  //mixer
  var mixerDescription = AudioComponentDescription()
  mixerDescription.componentType = kAudioUnitType_Mixer
  mixerDescription.componentSubType = kAudioUnitSubType_MultiChannelMixer
  mixerDescription.componentManufacturer = kAudioUnitManufacturer_Apple
  mixerDescription.componentFlags = 0
  mixerDescription.componentFlagsMask = 0

  AUGraphAddNode(graph, &mixerDescription, &audioEffectsController.mixerNode)
  AUGraphNodeInfo(graph, audioEffectsController.mixerNode, nil,
                    &audioEffectsController.mixerUnit)
  AudioUnitInitialize(audioEffectsController.mixerUnit!)

  AudioUnitSetParameter(mixerUnit!, kMultiChannelMixerParam_Volume, kAudioUnitScope_Input, 0, 1.0, 0);
    AudioUnitSetParameter(mixerUnit!, kMultiChannelMixerParam_Volume, kAudioUnitScope_Output, 0, 1.0, 0);


  //connect the nodes
  AUGraphConnectNodeInput(graph, sourceNode, sourceOutputBusNumber, filterNode, 0)
  AUGraphConnectNodeInput(graph, filterNode, sourceOutputBusNumber, dynamicProcessorNode, 0)

  AUGraphConnectNodeInput(graph, sourceNodeCopy, sourceOutputBusNumber, mixerNode, 0)
  AUGraphConnectNodeInput(graph, fiterNode, sourceOutputBusNumber, mixerNode, 0)

  //connect the mixer to the output
  AUGraphConnectNodeInput(graph, audioEffectsController.mixerNode, 0, destinationNode, destinationInputBusNumber)

Answer 1

在您的代码中，您像这样连接节点

AUGraphConnectNodeInput(graph, sourceNodeCopy, sourceOutputBusNumber, mixerNode, 0)
AUGraphConnectNodeInput(graph, fiterNode, sourceOutputBusNumber, mixerNode, 0)

如果这样做，您会将 sourceNodeCopy 和 filterNode 连接到 MixerNode 的相同输入 (0)。但是只能连接一个...

你应该试试这个

AUGraphConnectNodeInput(graph, sourceNodeCopy, sourceOutputBusNumber, mixerNode, 0)
AUGraphConnectNodeInput(graph, fiterNode, sourceOutputBusNumber, mixerNode, 1)

在 Spotify iOS SDK 中混合两个 AUNode

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