Re: Audio Converter and Endians problem
Re: Audio Converter and Endians problem
- Subject: Re: Audio Converter and Endians problem
- From: Jeff Moore <email@hidden>
- Date: Tue, 28 Jan 2003 14:35:43 -0800
Yup, that's exactly it. When the format was defined way back when, the
Sound Manager and it's usage of format information were used as the
model. Consequently, all the 4CC's and definitions used were the same.
Further, as the Sound Manager increased the number of formats it
supported (including little endian formats), so did the number of
constants used in AIFC files.
I don't know where the formal specification is kept, but there is a
description of AIFC in Inside Macintosh that dates to at least 1996
(and is probably a re-print/update of something printed even earlier).
You can read all about it on our Developer web site (no log-ins
required as far as I could tell). Just search for AIFC in the search
field at
http://developer.apple.com.
On Tuesday, January 28, 2003, at 12:15 PM, john wrote:
Hi Mark,
So is that what the sowt or whatever it is represents? If so, that
would be easy enough to add support for.
-- John
It used to be that you could download all of the headers from the
Apple Developer Support web site, though they're going to be in
StuffIt file or .smi disk image, so if you can't expand that, then
it's not going to do you any good. Search around on the Apple
Developer web site, the headers might still be there. They used to
be in the MPW SDK, though I believe that MPW has given way to Project
Builder, so you might just have to download that and see if you can
expand it to get to the headers.
You can read an AIFF or AIFC file on a PC just as easily as a Mac can
read a WAVE file (in fact, a WAVE file and an AIFF file look very
similar).
An AIFF and AIFC file have all of its fields described with big
endian values, but an AIFC file also describes a compressed data
section. Once you get to the DATA section, you have to interpret it
with the knowledge gained from parsing the format section of the
AIFC. For purposes of making things simple, endian conversion is
considered to be a compression, which is why it requires an AIFC file
to contain it. In this case that means you parse the format to know
that the data is little endian format, and then reading it as little
endian data.
--
Mark Cookson
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.
--
Jeff Moore
Core Audio
Apple
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.