ios - How to generate thumb image for 1 second video in swift?

Question

I am not able to generate thumbnail for 1 second video. I have tried below code but it generates black image every time. I have tried passing timescale as (0,30), (0,1). It is working if video is above 1.5 seconds.

static func thumbnailFromVideo(videoUrl: URL, time: CMTime) -> UIImage {
    let asset: AVAsset = AVAsset(url: videoUrl) as AVAsset
    let imgGenerator = AVAssetImageGenerator(asset: asset)
    imgGenerator.appliesPreferredTrackTransform = true
    do {
        let cgImage = try imgGenerator.copyCGImage(at: time, actualTime: nil)
        let uiImage = UIImage(cgImage: cgImage)
        return uiImage
    } catch {
        
    }
    return UIImage()
}

Answer 1

If you need a frame accurate thumbnail you need to set the requested time tolerance before and after to zero:

From the docs:

Set the values of requestedTimeToleranceBefore and requestedTimeToleranceAfter to zero to request frame-accurate image generation; this may incur additional decoding delay.

---

imgGenerator.requestedTimeToleranceBefore = .zero
imgGenerator.requestedTimeToleranceAfter = .zero