Apple

On Mar 29, 2011, at 6:38 PM, Wil Macaulay wrote:

I wrote some code to read aac and mp3 metadat, but not write. If there is any interest (and no current implementation) I could make it available through github or the like.

wil

On Tue, Mar 29, 2011 at 6:34 PM, Brian Gerstle <email@hidden> wrote:

Hello everyone,

I was wondering if anyone has experience reading & writing metadata to an audio file in iOS. So far we've tried:
AudioFileGet/SetProperty

kAudioFilePropertyInfoDictionary
kAFInfoDictionary_Comments
kAudioFilePropertyID3Tag

I'm getting the 'pty?' error code returned when I try to write to the info dictionary or read the ID3 tag. Also, the only "visible" key/value pair when I get the dictionary is the "approximate duration." I've attached some code to demonstrate how I'm trying to use these functions.

Thanks in advance!

Brian

P.S.
My colleague also posted to Apple's Core Audio support forum:
https://devforums.apple.com/message/409115#409115

{
  NSURL* url = [ NSURL fileURLWithPath: path2 ];

   OSStatus err;
   AudioFileID fileID;

   err = AudioFileOpenURL ((CFURLRef)url, kAudioFileReadWritePermission, kAudioFileWAVEType,&fileID );

   if (err == noErr)
   {

   CFDictionaryRef fileDict = nil;

   UInt32 size = sizeof(fileDict);

   err = AudioFileGetProperty(fileID, kAudioFilePropertyInfoDictionary, &size, &fileDict);

   if (err == noErr)

   {

   NSDictionary* dict = (NSDictionary*) fileDict;

   NSLog(@"%@",dict);

   NSMutableDictionary* dict2 = [ [ NSMutableDictionary alloc ] init ];

   [ dict2 addEntriesFromDictionary:dict ];
   [ dict2 setObject:@"test" forKey: [ NSString stringWithUTF8String:kAFInfoDictionary_Comments ] ];

   err = AudioFileSetProperty(fileID, kAudioFilePropertyInfoDictionary, size, dict2);

   if (err == noErr)
   {
// this point isn't reached

   NSLog(@"saved");
   }
   }

   AudioFileClose(fileID);
   }
}

...

{
UInt32 outDataSize = 0;
   UInt32 isWritable = 0;

// 'pty?' error here
   err = AudioFileGetPropertyInfo(fileID,kAudioFilePropertyID3Tag,&outDataSize,&isWritable);

   NSLog(@"outDataSize %d isWritable %d",outDataSize,isWritable);

   unsigned char* id3data = malloc(outDataSize);

   err = AudioFileGetProperty(fileID, kAudioFilePropertyID3Tag, &outDataSize, id3data);

   err++;
}

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References:
	>iOS audio file metadata (From: Brian Gerstle <email@hidden>)
	>Re: iOS audio file metadata (From: Wil Macaulay <email@hidden>)
	>Re: iOS audio file metadata (From: Brian Gerstle <email@hidden>)