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Re: AU "offline" processing
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Re: AU "offline" processing


  • Subject: Re: AU "offline" processing
  • From: David Duncan <email@hidden>
  • Date: Thu, 30 Jan 2003 22:26:52 -0500

On Thursday, January 30, 2003, at 05:14 PM, Marc Poirier wrote:

I was wondering if there is a way to write AUs that input more audio than
they output or vise versa. I guess that such an AU would have to be a
decidedly "offline" processor since such stuff can not be done in
realtime. I know that there's a lot of format negotiation possibilities
in the API, but I don't see anything about declaring offline vs. realtime
mode and basically I wonder, if I managed to write an AU that did time
compression for example, would it even run in any hosts out there and is
there a way for hosts to even do it right if they wanted to. Any wisdom
to be shared on this issue would be appreciated...

It would be fairly easy to design an AudioUnit that output more/less audio that it input, since the whole system is a pull mechanism you would just have to put a buffer between the AU's input & output.

Doing a compressor/decompressor is a little more complicated. Decompression would be handled via either a file format plugin or some other convertor plugin that knows about a particular format. You can then just insert a rate convertor after it for rate conversion. A compressor you would probably do as an AudioOutputUnit, as you will likely be writing the compressed audio either to a file or some other output device.
--
Reality is what, when you stop believing in it, doesn't go away.
Failure is not an option. It is a privilege reserved for those who try.

David Duncan
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