Re: Capturing Data coming OUT of an AUGraph
Re: Capturing Data coming OUT of an AUGraph
- Subject: Re: Capturing Data coming OUT of an AUGraph
- From: Mark Gilbert <email@hidden>
- Date: Sat, 19 Feb 2005 13:24:28 +0000
I did wonder about adding an additional bus output to my Matrix mixer
(getting the same data as the output feeding the output device. This
might actually be better for me anyway.
This could be fed to an output unit of type 'kAudioUnitIO_HALOutput'
- perhaps this AU can be used to gather the data. Anyone have any
info on this type of output unit ?
I do just want to fill a buffer, but there is very little
documentation, it would seem for this type of thing.
I dont have the expertise to setup a complex AU chain manually, so I
am relying on the simplicity of AUGraph, but just accessing the
rendered data somehow.
I suppose this is exactly the same type of setup people would want to
record the output of an AUGraph to disk, or for complex metering of
output data. I actually want to feed the output data back to the
input stage (muted, but dont ask why !). Incidentally, I would be
interested to know how I can calculate the latency between the input
and output of my AUGraph such that I could compensate the output
samples to be concurrent with those entering the AUGraph.
Any suggestions on calls to look for or example code would be appreciated.
Cheers
Mark.
At 1:05 pm +0100 19/2/05, pwicker wrote:
On Feb 19, 2005, at 12:30 PM, Mark Gilbert wrote:
Folks.
I have an AUGraph which is primarily data being pulled into a
Matrix Mixer feeding an output device.
I want to 'tap into' the data which has been mixed and is on its
way out, so I can record it to disk.
Is there a simple callback I can insert to get this data as it
passes through, without radically rewiring my architecture ?
I don't know well the AUGraph so I may be wrong. As far as I know,
you don't have such a callback. What you could do is write a special
AU that you could insert in front of your graph. Within the Render
callback of this AU you should pass the audio buffers to a worker
thread using a non blocking FIFO or ring buffer. This worker thread
would then write the audio to the disk. What you must never do is
call a disk API from the render callback. I believe there's a sample
code in the SDK which shows how to deal with a disk writer thread
(DiskWriterAUGraph I think but not sure).
Thanks
Mark Gilbert.
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Philippe
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email@hidden
Tel: +44 208 340 5677
fax: +44 870 055 7790
http://www.gallery.co.uk
New Product ! - Zen MetaCorder
Location Sound Field Recorder
http://www.metacorder.info
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