UIImages to Video with AVAssetWriter produces black frames flickering for < 800 images

Question

I'm stuck for weeks!

I tried all of the solutions out there on stackoverflow which they work fine for around ~ 0 to 500 images or 50 seconds on 12 fps, but for longer videos there's black flickering after ~50 seconds depending on what iphone, with iphone 6 happens after 50 sec on iphone 8 it happens after 1:30

I tried the accepted answer from this link writeImagesAsMovie() function

sometimes I get memory allocation problem, sometimes I don't, But the black flickering persists.

 // MARK: - Fill Pixel Buffer -

private func fillPixelBufferFromImage(image: UIImage, pixelBuffer: CVPixelBuffer) {
    CVPixelBufferLockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))
    let pixelData = CVPixelBufferGetBaseAddress(pixelBuffer)
    let rgbColorSpace = CGColorSpaceCreateDeviceRGB()

    // Create CGBitmapContext
    let context = CGContext(
      data: pixelData,
      width: Int(720),
      height: Int(720),
      bitsPerComponent: 8,
      bytesPerRow: CVPixelBufferGetBytesPerRow(pixelBuffer),
      space: rgbColorSpace,
      bitmapInfo: CGImageAlphaInfo.premultipliedFirst.rawValue
    )


    // Draw image into context"
    context?.draw(image.cgImage!, in: CGRect(x: 0, y: 0, width: 720, height: 720))

    CVPixelBufferUnlockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))


    //UIGraphicsEndImageContext()
}

Answer 1

Things that helped getting the desired result... using UIImageJPEGRepresentation instead of PNG, the dimensions have to be multiple of 16... :) and newer iphones can handle more images