CODEWITHSUNDEEP
iosavfoundation
Aiden Luo
Aiden Luo

Reputation: 31

How to set metadata for AVFileTypeMPEG4 file via AVAssetExportSession?

I'm trying to use AVAssetExportSession to set the metadata of a AVFileTypeMPEG4 type file,but it doesn't work,if I change the file type to AVFileTypeQuickTimeMovie,it works.But I need mp4 file,I can't find any document say AVFileTypeMPEG4 file can not be set metadata,Has anyone set meta successfully? Here is the code that I used:

NSMutableArray *metadata = [NSMutableArray array];
    AVMutableMetadataItem *metaItem = [AVMutableMetadataItem metadataItem];
    metaItem.key = AVMetadataCommonKeySource;
    metaItem.keySpace = AVMetadataKeySpaceCommon;
    metaItem.value = @"Test metadata";
    [metadata addObject:metaItem];
AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:composition presetName:AVAssetExportPresetMediumQuality];
        exportSession.metadata = metadata;
        exportSession.audioMix = audioMix;
        exportSession.videoComposition = videoComposition;
        exportSession.outputFileType = AVFileTypeMPEG4;//AVFileTypeQuickTimeMovie;
        NSString *outputFilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"testMetadata.mp4"];
        exportSession.outputURL = [NSURL fileURLWithPath:outputFilePath];
        [exportSession exportAsynchronouslyWithCompletionHandler:^{
            dispatch_async(dispatch_get_main_queue(), ^{
                if (exportSession.status == AVAssetExportSessionStatusCompleted) {
                    //todo
                }else{
                    //todo
                }
            });
        }];

Upvotes: 3

Views: 2190

Answers (2)

scosman
scosman

Reputation: 2585

Apple filters metadata depending on the output type. They don't consider iTunes metadata valid for MPEG4 output, so they strip it.

Some options:

  • Use AVFileTypeQuickTimeMovie > MOV is closely related to MP4, and is often compatible. This depends on what you are looking to do.

  • Try other types (some people report success with the MPV type)

  • use a library to write custom data/atoms (mp4v2 works for example). Lots of work, but the only real way to achieve it.

Upvotes: 1

NeckCracker
NeckCracker

Reputation: 11

Try it with 


    metaItem.key = AVMetadataiTunesMetadataKeyDescription;
    metaItem.keySpace = AVMetadataKeySpaceiTunes;

tried the other keyspaces but only itunes worked for me.

Upvotes: 1

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