Re: Audio files and loop marker question
Re: Audio files and loop marker question
- Subject: Re: Audio files and loop marker question
- From: Doug Wyatt <email@hidden>
- Date: Mon, 24 Jul 2006 14:27:16 -0700
On Jul 24, 2006, at 13:58 , tahome izwah wrote:
Thanks Doug, that is very helpful information.
If you don't mind (another) innocent question - what AudioFile call do
I use to retrieve marker information (an AudioFileMarkerList I guess)?
The only one I see is AudioFileGetProperty but I don't seem to be able
to find an explanation of the relevant property IDs that I need to
use... For AudioFileGetProperty the documentation just says "retrieves
the property information for the given property ID and selected
specifier" which isn't very helpful really.
The properties you want are:
@constant kAudioFilePropertyMarkerList
access the list of markers defined in the file. returns an
AudioFileMarkerList.
The CFStringRefs in the returned structs must be released by the
client.
(available in 10.2.4 and later)
@constant kAudioFilePropertyRegionList
access the list of regions defined in the file. returns an Array
of AudioFileRegions.
The CFStringRefs in the returned structs must be released by the
client.
(available in 10.2.4 and later)
You'll want to call AudioFileGetPropertyInfo to obtain the size of
the list, allocate storage for it, then AudioFileGetProperty to fetch
it.
The only in-depth documentation that comes up refers to CAF files and
the marker chunk and I don't think this is relevant in my case since
I'm dealing with AIFF and WAVE files mainly.
Also, is there a way to get an AudioFileID from an ExtAudioFileRef?
Not currently. We have an enhancement request to provide that, though
since that would appear in Leopard at the earliest, you might as well
just open/create the AudioFile yourself and then wrap it in the
ExtAudioFileRef as I mentioned earlier.
Doug
--
Doug Wyatt
Core Audio, Apple
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