将kAudioUnitSubType_MultiChannelMixer添加到AUGraph时无声
我在将混音器单元插入AUGraph
时遇到问题,该问题在Mac OS和iOS上均可正常工作。将kAudioUnitSubType_MultiChannelMixer添加到AUGraph时无声
我的工作曲线图如下所示:
(My Audio render callback) <- [Format converter] <- [DefaultOutput]
此外,我能够成功插入EQ单元是这样的:
(My Audio render callback) <- [Format converter] <- [GraphicEQ] <- [DefaultOutput]
我的目标是要插入一个混频器单元,但没有EQ,所以我可以独立于iOS上的系统音量来控制图表的音量。但是,当我设置图表,似乎看起来好吧,但我得到的只是沉默。
这里的图是什么样子:
(My Audio render callback) <- [Format converter] <- [MultiChannelMixer] <- [DefaultOutput]
...和CAShow的输出:
AudioUnitGraph 0x397000:
Member Nodes:
node 1: 'auou' 'def ' 'appl', instance 0x8039704d O I
node 2: 'aumx' 'mcmx' 'appl', instance 0x8039704e O I
node 3: 'aufc' 'conv' 'appl', instance 0x8039704f O I
Connections:
node 3 bus 0 => node 2 bus 0 [ 2 ch, 44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
node 2 bus 0 => node 1 bus 0 [ 2 ch, 44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
Input Callbacks:
{0x100035d90, 0x10037cd60} => node 3 bus 0 [2 ch, 44100 Hz]
CurrentState:
mLastUpdateError=0, eventsToProcess=F, isRunning=T (1)
而且,最后,这是建立与错误检查和iOS-图码删除特定的代码:
// A description of the output device we're looking for.
AudioComponentDescription outputDescription;
outputDescription.componentType = kAudioUnitType_Output;
outputDescription.componentSubType = kAudioUnitSubType_DefaultOutput;
outputDescription.componentManufacturer = kAudioUnitManufacturer_Apple;
outputDescription.componentFlags = 0;
outputDescription.componentFlagsMask = 0;
// A description of the mixer unit
AudioComponentDescription mixerDescription;
mixerDescription.componentType = kAudioUnitType_Mixer;
mixerDescription.componentSubType = kAudioUnitSubType_MultiChannelMixer;
mixerDescription.componentManufacturer = kAudioUnitManufacturer_Apple;
mixerDescription.componentFlags = 0;
mixerDescription.componentFlagsMask = 0;
// A description for the libspotify -> standard PCM device
AudioComponentDescription converterDescription;
converterDescription.componentType = kAudioUnitType_FormatConverter;
converterDescription.componentSubType = kAudioUnitSubType_AUConverter;
converterDescription.componentManufacturer = kAudioUnitManufacturer_Apple;
converterDescription.componentFlags = 0;
converterDescription.componentFlagsMask = 0;
// Create an AUGraph
OSErr status = NewAUGraph(&audioProcessingGraph);
// Open the graph. AudioUnits are open but not initialized (no resource allocation occurs here)
AUGraphOpen(audioProcessingGraph);
// Add audio output...
status = AUGraphAddNode(audioProcessingGraph, &outputDescription, &outputNode);
// Add mixer
status = AUGraphAddNode(audioProcessingGraph, &mixerDescription, &mixerNode);
// Get mixer unit so we can change volume etc
status = AUGraphNodeInfo(audioProcessingGraph, mixerNode, NULL, &mixerUnit);
// Set mixer bus count
UInt32 busCount = 1;
status = AudioUnitSetProperty(mixerUnit, kAudioUnitProperty_ElementCount, kAudioUnitScope_Input, 0, &busCount, sizeof(busCount));
// Create PCM converter
status = AUGraphAddNode(audioProcessingGraph, &converterDescription, &inputConverterNode);
// Connect converter to mixer
status = AUGraphConnectNodeInput(audioProcessingGraph, inputConverterNode, 0, mixerNode, 0);
// Connect mixer to output
status = AUGraphConnectNodeInput(audioProcessingGraph, mixerNode, 0, outputNode, 0);
// Set render callback
AURenderCallbackStruct rcbs;
rcbs.inputProc = AudioUnitRenderDelegateCallback;
rcbs.inputProcRefCon = (__bridge void *)(self);
status = AUGraphSetNodeInputCallback(audioProcessingGraph, inputConverterNode, 0, &rcbs);
// Init Queue
status = AUGraphInitialize(audioProcessingGraph);
AUGraphUpdate(audioProcessingGraph, NULL);
AUGraphStart(audioProcessingGraph);
...当然,在发布我的问题后,我偶然发现回答。
看来,至少在Mac OS上,混音器的输入音量默认为0.0。手动设置输入音量固定它:
status = AudioUnitSetParameter(mixerUnit, kMultiChannelMixerParam_Volume, kAudioUnitScope_Input, 0, 1.0, 0);
对于我设置kAudioUnitScope_Output而不是KAudioUnitScope_Input。 – user523234 2012-09-25 00:24:25
供参考:我必须设置输入和输出以获取信号。 – hobotron 2012-11-19 17:01:39
所以这与GraphicEQ而不是混音器?使用相同的回调?你能在没有回调的情况下工作吗? – hooleyhoop 2012-03-28 09:47:01