Crash when applying filter to AVVideoComposition - ios

Question

I want to apply filter to AVVideoComposition by function:
init(asset: AVAsset, applyingCIFiltersWithHandler: (AVAsynchronousCIImageFilteringRequest) -> Void)
In which, the asset is AVComposition. When an AVPlayerItem plays this composition with the videoComposition, app crashes with error:
reason: '*** -[AVCoreImageFilterCustomVideoCompositor startVideoCompositionRequest:] Expecting video composition to contain only AVCoreImageFilterVideoCompositionInstruction'
I wonder how to fix the crash.
PS: I have two videoTracks in composition, each timeRange has its instruction

Answer 1

You can't use both AVVideoCompositionLayerInstruction and applyingCIFiltersWithHandler.
Intead, you need to apply directly the transform in the filter.
This can be done by applying it to the source image.
request.sourceImage.transformed(by: transform)

Answer 2

I guess you are trying to add AVVideoCompositionLayerInstruction to the AVVideoComposition.
Try the simple approach first and see if you need any changes:
AVURLAsset *asset = [AVURLAsset assetWithURL:videoURL];
CIFilter *filter = [CIFilter filterWithName:#"CIHueAdjust"]; // the filter you want to add: https://developer.apple.com/library/content/documentation/GraphicsImaging/Reference/CoreImageFilterReference/index.html#//apple_ref/doc/filter/ci/
AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoCompositionWithAsset:asset applyingCIFiltersWithHandler:^(AVAsynchronousCIImageFilteringRequest * _Nonnull request) {
// set filter input image
[filter setDefaults];
[filter setValue:sourceImage forKey:kCIInputImageKey];
// hue
NSNumber *angle = [NSNumber numberWithFloat:0.8];
[filter setValue:angle forKey:kCIInputAngleKey];
CIImage *outputImage = filter.outputImage;
[request finishWithImage:outputImage context:nil];
}];
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPreset1920x1080];
exportSession.outputFileType = AVFileTypeQuickTimeMovie;
exportSession.outputURL = outputURL;
exportSession.videoComposition = videoComposition;
// export the session async
[exportSession exportAsynchronouslyWithCompletionHandler:^{
switch (exportSession.status) {
case AVAssetExportSessionStatusCompleted:
NSLog(#"Yeah!");
break;
default:
NSLog(#"Nooo!");
break;
}
}];

Answer 3

AVMutableVideoComposition:videoCompositionWithAsset:applyingCIFiltersWithHandler only support iOS 9+ and if you only need export video with CIFilter, that's ok.
Configure more videoComposition instructions will cash, for example add kind of roateLayerInstruction to AVAssetTrack.
I have same issue in this situation and custom AVVideoCompositing maybe the better solution. some good demos about how to customize videoCompositor demo1 demo2.
I am working on this problem this week.