simonkim

import Foundation
import AVFoundation

struct AVFTransition {
    let duration: CMTime = CMTime(seconds: 1.0, preferredTimescale: 1000)
    
    /// tracks must contain 2 elements
    func instruction(at startTime: CMTime, tracks: [AVAssetTrack]) -> AVMutableVideoCompositionInstruction {
        let timeRange = CMTimeRangeMake(startTime, self.duration)
        let instTrans = AVMutableVideoCompositionInstruction()