ID3 tags from AAC files
ID3 tags from AAC files
- Subject: ID3 tags from AAC files
- From: Jeremy Dronfield <email@hidden>
- Date: Wed, 5 Jan 2005 14:30:41 +0000
Is there a way to extract ID3 tags from AAC (.m4a) files encoded with
iTunes? I've been using QuickTime GetMovieUserData() to extract tags
from NSMovies created from mp3 tracks, but the same method doesn't work
with m4a files.
The code I'm using is based on the QT example at
<http://developer.apple.com/qa/qa2001/qa1135.html>. Can anyone suggest
what modifications might be necessary to use this with AAC tracks? I
assume the ID3 tags must be preserved in the converted files, since
iTunes presumably uses them.
#import <QuickTime/Movies.h>
const UInt8 kUserDataIsText = 0xA9; // the copyright symbol
- (void)printTags
{
NSURL *trackURL = [NSURL fileURLWithPath:filePath];
NSMovie *track = [[NSMovie alloc] initWithURL:trackURL byReference:NO];
UserData inUserData = GetMovieUserData([track QTMovie]);
OSType udType;
short count, i;
char nul = 0;
Handle hData = NULL;
Ptr p;
OSErr err = noErr;
hData = NewHandle(0);
udType = GetNextUserDataType(inUserData, 0);
if(0 != udType) {
NSLog(@"\nMeta-data:\n";);
do {
count = CountUserDataType(inUserData, udType);
for(i = 1; i <= count; i++) {
if((udType>>24) == kUserDataIsText) {
err = GetUserDataText(inUserData, hData, udType, i, langEnglish);
if (err) goto bail;
PtrAndHand(&nul, hData, 1);
p = *hData;
while(*p) {
if (*p == kReturnCharCode)
*p = ' ';
p++;
};
HLock(hData);
NSLog(@" %c%c%c%c: %s\n", (char)(udType>>24),
(char)(udType>>16),
(char)(udType>>8),
(char)udType, *hData);
HUnlock(hData);
} else {
err = GetUserData(inUserData, hData, udType, i);
if (err)
goto bail;
NSLog(@" %c%c%c%c: [%d bytes]\n",
(char)(udType>>24),
(char)(udType>>16),
(char)(udType>>8),
(char)udType, GetHandleSize(hData));
}
}
udType = GetNextUserDataType(inUserData, udType);
}
while(0 != udType);
}
bail:
NSLog(@"\n");
DisposeHandle(hData);
}
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