Re: 64bit processing possible?

Subject: Re: 64bit processing possible?
From: William Stewart <email@hidden>
Date: Mon, 3 Aug 2009 11:49:46 -0700
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all that you need to do is:

- accept an ASBD that describes a 64bit float sample description.

That would look something like (for an AU using deinterleaved, the ASBD describes the format of one channel)

AudioStreamBasicDescription streamFormat; streamFormat.mFormatID = kAudioFormatLinearPCM; // the specific encoding type of audio stream streamFormat.mFormatFlags = kAudioFormatFlagsNativeFloatPacked | kAudioFormatFlagIsNonInterleaved; // we want native ordered, packed, floating point, deinterleaved streamFormat.mBytesPerPacket = sizeof(Float64); streamFormat.mBytesPerFrame = streamFormat.mBytesPerPacket; streamFormat.mFramesPerPacket = 1; streamFormat.mBitsPerChannel = 64;

streamFormat.mChannelsPerFrame = myNumChannels;
streamFormat.mSampleRate = mySampleRate;

So - your AU would see this kind of ASBD from its host. Then it knows that the audio data it gets is 64bit float.

You would have to overide this check in AUBase, where it is checking the format against the AU Canonical definition, specifically: bool MyAUDoubleClass::ValidFormat(AudioUnitScope inScope, AudioUnitElement inElement, const CAStreamBasicDescription & inNewFormat)

(You can see how this is used in AUBase::DispatchSetProperty - case kAudioUnitProperty_StreamFormat)

That's it.

Bill

On Aug 2, 2009, at 8:49 AM, Alejandro wrote:

Bill,

You asserted that it is possible to create an Audio Unit with 64bit external format support. I have never created an AU, but how is this done?

Thank you,

Alejandro

--
Alejandro Palencia
Open Studio Networks
www.openstudionetworks.com
+34 667440770
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  >Re: 64bit processing possible? (From: Alejandro <email@hidden>)




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References:
	>Re: 64bit processing possible? (From: Alejandro <email@hidden>)