kAudioUnitErr_TooManyFramesToProcess

Question

garethw_silicondust OP

Created Jan ’18

Replies 4

Boosts 0

Views 2.9k

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Keep getting kAudioUnitErr_TooManyFramesToProcess : inFramesToProcess=3072, mMaxFramesPerSlice=1120

when playing via bluetooth headphones.

Works fine when playing through mac speakers or hdmi output to tv.

I am using AVAudioEngine and AVAudioPlayerNode to play raw audio buffers scheduled to it.

It works fine except when bt headphones are connected then I get this error as soon as the AVAudioEngine is started - even before any buffers have been scheduled to play.

I have played around with kAudioUnitProperty_MaximumFramesPerSlice and kAudioDevicePropertyBufferFrameSize.

I can get the error to 'go away' by playing around with certain values but scheduled buffers don't play and I don't get a scheduled buffer completion callback.

No audio through the headphones.

I am totally stuck in how to proceed and what step to try next.

This is using swift language.

Many examples I see suggets setting kAudioUnitProperty_MaximumFramesPerSlice to the value returned by kAudioDevicePropertyBufferFrameSize.

But those code examples are in objc so I am struggling to find a swift equivalent.

Though I can set the mfps for the output node, I don't know how to set it for the other nodes in the 'tree'.

for example I am using the mixer to control volume and the examples show this:

AudioUnitSetProperty(mMixer, kAudioUnitProperty_MaximumFramesPerSlice, kAudioUnitScope_Global, 0, &maxFPS, sizeof(maxFPS));

However mMixer (audio_engine.mainMixerNode) is not an acceptable parameter to the swifts AudioUnitSetProperty() api.

So I am not sure I am configuring the nodes properly anyway.

The engine has a number of nodes as follows:

AVAudioPlayerNode->AVAudioUnitVarispeed->mainMixerNode->outputNode

I have removed the varispeed and mixer from the connections to simplify the setup so I have

AVAudioPlayerNode->outputNode

But still no luck with bt headphones, works fine through the mac speakers etc.

Totally stuck and hope someone can help to shed some light on what I am doing wrong.

Thanks.

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Answer 1

garethw_silicondust OP

Jan ’18

No one seen an issue like this when playing audio to bt headphones?

kAudioUnitErr_TooManyFramesToProcess : inFramesToProcess=3072, mMaxFramesPerSlice=1120

0

Answer 2

DigitalAudioTom OP

Jan ’18

Hello,

Could you show us the setup and initialisation of your AVAudioEngine?

I'm not an expert with AVAudioEngine, but, in the case I don't use custom-built AUAudioUnit, only AVAudioNodes from AVFoundation framework, I wouldn't mess around with kAudioUnitProperty_MaximumFramesPerSlice or other low-level AudioToolbox properties. There is a maximumFramesToRender property on AUAudioUnit, but I don't know if it's advised to access the auAudioUnit property of AVAudioPlayerNode.

Another lead : check the values of IOBufferDuration and maxFramesPerSlice in your handleRouteChange, this might help changing the setup of your audioEngine accordingly.

Otherwise, I had this problem with custom built AUAudioUnit. As I didn't know how to fix this issue within my AUAudioUnit (I'm sure there is a proper way, but I didn't find it for the moment). I fixed it by setting the the kAudioUnitProperty_MaximumFramesPerSlice on the main output node :

AVAudioFrameCount maxFramesPerSlice = 4096;

AudioUnitSetProperty(self.audioEngine.outputNode.audioUnit, kAudioUnitProperty_MaximumFramesPerSlice, kAudioUnitScope_Global, 0, &maxFramesPerSlice, sizeof(maxFramesPerSlice));

I'm quite sure you're not supposed to do things like that, but it worked in my case 😉

Cheers

Tom

0

Answer 3

vincedev OP

Jun ’18

Yes, I did.

Surprisingly, when I turn audio input back to internal microphone in system sound preferenes, everything works as expected.

0

Answer 4

tallereric OP

Dec ’19

I also noticed this problem only when connected with BT headphones. I solved it by setting the system's audio input device to "Macbook Pro Microphone" instead of the BT headphones.

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