Re: magic cookies
Re: magic cookies
- Subject: Re: magic cookies
- From: David Duncan <email@hidden>
- Date: Tue, 14 Oct 2003 17:45:12 -0400
On Oct 14, 2003, at 04:50 PM, Stanko Juzbasic wrote:
On Tuesday, October 14, 2003, at 06:36 PM, Holger Hvrich wrote:
But as I understood the magic cookies, those are data structures
inside of AudioUnits e.g. holding information about compressed audio
files which are not to be understood by anybody else...
Why are these things suddenly needed for professional audio file
format ( 16-bit linear as low end )?
What do they serve for - ENCRYPTED COMPRESSION - (?)- iPod or Music
e-Commerce Copyright authorization ?
Magic cookies are for extra data that is needed to decompress the data.
For example AC3 audio decompression to less than full 5.1 should use a
down mix matrix that provides the coefficients for each channel so that
the down mix virtualizes correctly. Purportedly other formats can
require extra information to decode as well.
Why does QuickTIme utterly and consistently convert any AIFF file into
AIFC, whether asked so or not?
Does this also have to do with magic cookies?
There is only a small practical difference between AIFF and AIFC files,
such that if you can parse AIFF you can quite nearly parse AIFC as
well. There is truthfully no reason to write a plain AIFF file except
for backward compatibility, or if you just *must* save those extra 10
or 20 bytes that AIFC adds =).
--
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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| References: | |
| | >magic cookies (From: Stanko Juzbasic <email@hidden>) |