Is there any function to extract all the frames of a video that is downloaded and picked from Documents Directory in iOS Swift? - avasset

Question

I am trying to extract all the frames from a video. Code is working fine for the video in Bundle Path, but it fails when i give a link of the video or I try to pick the video from File Manager.
Following are the issues that i have encountered:
AVAsset throws an error "Error Domn=AVFoundationErrorDomain Code=-11838 "Cannot initialize an instance of AVAssetReader with an asset at non-local URL".
When video is picked from Documents Directory, the fetched asset tracks are always 0.
Following is the code that i am using right now.
let asset = AVAsset(url: URL(string: path!)!)
self.playerController.player = AVPlayer(playerItem: AVPlayerItem(asset: asset))
if let path = path {
let asset:AVAsset = AVAsset(url: URL(string: path)!)
self.playerController.player = AVPlayer(playerItem: AVPlayerItem(asset: asset))
self.player.play()
asset.loadTracks(withMediaType: .video) { fetchedTracks, err in
do{
let reader = try AVAssetReader(asset: asset)
// read video frames as BGRA
let trackReaderOutput = AVAssetReaderTrackOutput(track: (fetchedTracks?.first)!, outputSettings:[String(kCVPixelBufferPixelFormatTypeKey): NSNumber(value: kCVPixelFormatType_32BGRA)])
reader.add(trackReaderOutput)
reader.startReading()
while let sampleBuffer = trackReaderOutput.copyNextSampleBuffer() {
print("sample at time \(CMSampleBufferGetPresentationTimeStamp(sampleBuffer))")
if CMSampleBufferGetImageBuffer(sampleBuffer) != nil {
// process each CVPixelBufferRef here
guard let imageBuffer: CVPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return }
let ciimage = CIImage(cvPixelBuffer: imageBuffer)
self.frames.append(UIImage(ciImage: ciimage))
// see CVPixelBufferGetWidth, CVPixelBufferLockBaseAddress, CVPixelBufferGetBaseAddress, etc
}
}
self.collectionViewFrames.reloadData()
} catch let err {
print(err)
}
}
}