m4a metadata in AudioFile kAudioFilePropertyInfoDictionary
m4a metadata in AudioFile kAudioFilePropertyInfoDictionary
- Subject: m4a metadata in AudioFile kAudioFilePropertyInfoDictionary
- From: patrick machielse <email@hidden>
- Date: Thu, 22 Oct 2009 00:32:11 +0200
In my program I need to access (read-only) m4a file 'tag' metadata.
The documentation of AudioFile leads me to believe I should be able to
get at that information by asking for kAudioFilePropertyInfoDictionary
in AudioFileGetProperty(). However, the returned info dictionary
allways seems to contain just one key:
kAFInfoDictionary_ApproximateDurationInSeconds.
My Code boils down to this (written in Mail):
UInt32 writable = 0, size = 0;
OSStatus error = AudioFileGetPropertyInfo(fileID,
kAudioFilePropertyInfoDictionary, &size, &writable);
if ( error == noErr ) {
CFDictionaryRef info = NULL;
error = AudioFileGetProperty(fileID,
kAudioFilePropertyInfoDictionary, &size, &info);
if ( error == noErr ) {
NSLog(@"file properties: %@", (NSDictionary *)info);
}
}
The output always looks like this:
2009-10-22 00:00:23.546 file properties: {
"approximate duration in seconds" = "83.429";
}
This is the only key I _don't_ care about... It seems that nothing
else is implemented for m4a? I found a message on this forum to that
effect, but as it dates back to May 2005 I was hoping that things
would be different now.
http://lists.apple.com/archives/coreaudio-api/2005/May/msg00250.html
I'm left with 2 questions:
- If full support for m4a in kAudioFilePropertyInfoDictionary still
isn't there, which file formats _are_ properly supported?
- Which alternatives for accessing m4a tag info are advisable? There
is Quicktime API QTCopyMovieMetaData(), but I've read about issues
with that as well, and anno 2009 it just seems so wrong to delve into
QT :-). But if I must I will, of course... My solution should work on
10.4.
Thanks,
patrick
--
Patrick Machielse
Hieper Software
http://www.hieper.nl
email@hidden
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