AVMutableVideoCompositionLayerInstruction doesn't get applied

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I'm merging videos in a loop and try to apply opacity and scaling with a AVMutableVideoCompositionLayerInstruction - alas, it's not working.

Any ideas what I'm doing wrong?

for(NSDictionary *clip in collection[@"clips"]){

        AVMutableCompositionTrack   *compositionVideoTrack = [theMutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
        AVMutableCompositionTrack *compositionAudioTrack = [theMutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

        CMTime clipStart = insertPoint;

        NSString *movieName = [NSString stringWithFormat:@"collection_%li/recording_%li_%li.MOV", (long)editCollection, editCollection, [clip[@"clipID"] longValue]];

        NSURL *assetUrl = [NSURL fileURLWithPath:[usefulStuff pathForFile: movieName]];

        AVURLAsset *videoAsset = [AVURLAsset URLAssetWithURL:assetUrl options:nil];

        // Set Timerange

        totalTime = CMTimeAdd(totalTime, [videoAsset duration]);
        timeRange = CMTimeRangeMake(kCMTimeZero, [videoAsset duration]);

        AVAssetTrack *clipVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
        AVAssetTrack *clipAudioTrack = [[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];

        NSError *error;

        [compositionVideoTrack insertTimeRange:clipVideoTrack.timeRange ofTrack:clipVideoTrack atTime:insertPoint error:nil];   // Add video
        [compositionAudioTrack insertTimeRange:clipAudioTrack.timeRange ofTrack:clipAudioTrack atTime:insertPoint error:&error];    // Add audio

        AVMutableVideoCompositionLayerInstruction *passThroughLayerClip = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTrack];

        compositionVideoTrack.preferredTransform = clipVideoTrack.preferredTransform;


        CGAffineTransform scale = CGAffineTransformMakeScale(scaleFactorX, scaleFactorY);

        [passThroughLayerClip setTransform:scale atTime:kCMTimeZero];

        // Set Fade-In

        insertPoint = CMTimeAdd(insertPoint, [videoAsset duration]);

        [passThroughLayerClip setOpacity:0.0 atTime:[videoAsset duration]];

        [layerInstructions addObject:passThroughLayerClip];

        [transitionTimes addObject:[NSValue valueWithCMTime: insertPoint]];

        AVMutableVideoCompositionInstruction *passThroughInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
        passThroughInstruction.timeRange = CMTimeRangeMake(clipStart, videoAsset.duration);
        passThroughInstruction.layerInstructions = [NSArray arrayWithObject:passThroughLayerClip];
        [videoCompositionInstructions addObject:passThroughInstruction];

        assetUrl = nil;
        videoAsset = nil;
        passThroughLayerClip = nil;


    }

asked 29 secs ago

Swissdude

835

AVMutableVideoCompositionLayerInstruction doesn't get applied