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Re: Using the new "Input" bus of the DefaultOutputUnit
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Re: Using the new "Input" bus of the DefaultOutputUnit


  • Subject: Re: Using the new "Input" bus of the DefaultOutputUnit
  • From: Brad Ford <email@hidden>
  • Date: Tue, 11 Nov 2003 21:21:16 -0800

_HasIO is a getter only. If you want to set up which busses are active on an output unit, you need to use the setter equivalent of the _HasIO property, _EnableIO.

As for why you are getting a bus count of 1 on your DefaultOutputUnit, I would guess it's because you haven't enabled the input side of your output unit. By default, AudioOutputUnits are instantiated as output-only units. Input is disabled.

Also, what is your default device? Is it a USB device? If it is, AMS is tricking you--it's actually coalescing two AudioDevice's into one behind your back, since USB devices present their input and their output as two separate devices.

HTH.
-Brad Ford
QuickTime Engineering

On Nov 11, 2003, at 6:58 PM, Robert Grant wrote:

Researching the AudioUnitRender issue in the other thread helped me find this property for enabling Input on the OutputUnit:

status = AudioUnitSetProperty(output,
kAudioOutputUnitProperty_HasIO,
kAudioUnitScope_Input,
1,
&data,
sizeof(data) );

But setting this property gets me an InvalidProperty error...

I think I interpreted this correctly: "scope input, element 1 = input" but the comments in the header file are a little hard to parse...

But perhaps it's getting too late! :-)

Robert.

On Nov 11, 2003, at 9:01 PM, Robert Grant wrote:

I'm also trying to use the new input capability of the DefaultOutputUnit but I'm not sure how it's supposed to work... actually I don't think it is working.

From the docs: "Any of these I/O units may be used to pull input data from its associated audio device, through any number or combination of audio units or audio unit graphs, and output back through the I/O unit. The I/O unit itself has two busses: 0 and 1, where the 0 bus is designated as the output, and the 1 bus is the input bus. The connections between the output of the 0 bus and the audio device and the input of the 1 bus and the audio device are made when the unit is associated with the device."

However when I query the bus count of the output unit I get only one bus which is probably not the case despite the fact that AMS is showing I have input and output enabled.

Should I get two buses reported for DefaultOutputUnit?

Thanks,

Robert.
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  • Follow-Ups:
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      • From: Robert Grant <email@hidden>
References: 
 >Using the new "Input" bus of the DefaultOutputUnit (From: Robert Grant <email@hidden>)
 >Re: Using the new "Input" bus of the DefaultOutputUnit (From: Robert Grant <email@hidden>)

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