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Re: AudioCodec questions
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Re: AudioCodec questions


  • Subject: Re: AudioCodec questions
  • From: Bill Stewart <email@hidden>
  • Date: Mon, 2 Jun 2003 17:10:53 -0700

Yes indeed - this will be covered in some detail at WWDC as we've done some extensive work in this area from the client side - basically it will be hooked into the AudioConverter...

There are many details about writing them that we hope to sketch out in the QT and Audio session, then we can follow up in the "hands on" lab session (still figuriing out when/where this will be)

Bill

On Sunday, June 1, 2003, at 11:45 AM, Chris Reed wrote:

I think the one of the Apple guys said something a while back about this. From what I remember, there is currently no way to iterate over or load AudioCodecs. And there is no documentation available. They've said before that if you want to write a codec, ask your questions on this list and they'll help.

-chris


On Saturday, May 31, 2003, at 08:15 PM, Brian Willoughby wrote:

Hello,

There seems to be no documentation whatsoever for AudioCodecs outside the
source code in the AudioCodecSDK. That source does provide internal
information on an AudioCodec, but since I do not see any source for loading an
AudioCodec, a few questions remain about the interface between a new
AudioCodec, the Mac OS X system, and any potential host application. The only
place in the documentation which mentions AudioCodecs promises that they are
described in another document, but I cannot find that document.


How does one test an AudioCodec?

What programs load AudioCodecs?

If there are any programs that load all available AudioCodecs, how exactly do
they determine which AudioCodec to use?

What is the MagicCookie implied by kAudioCodecPropertyMagicCookie?

Are there any rules for setting the value of kPrimaryResourceID besides those
mentioned in the source? i.e. as long as I leave a gap for two consecutive
values, can I pick any value for kPrimaryResourceID?

Are negative values reserved by Apple for kPrimaryResourceID?

Where can I learn more about properties like
kAudioCodecPropertyMaximumPacketByteSize,
kAudioCodecPropertyRequiresPacketDescription,
kAudioCodecPropertyPacketBytesSizes, and kAudioCodecPropertyPacketFrameSize?


I realize that the answers to some of these questions should be similar to
those for a general AudioUnit, but I suspect that some of the details will be
slightly different for an AudioCodec.


Note: I am hoping to have an AudioCodec completed before WWDC 2003 begins, so
I do not wish to wait for the answers to be revealed in a session at the
conference. :-)

Thanks!

Brian Willoughby
Sound Consulting
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References: 
 >Re: AudioCodec questions (From: Chris Reed <email@hidden>)

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