IOS AVPlayer get fps

Question

Im trying to figure out how to retrieve a videos frame rate via AVPlayer. AVPlayerItem has a rate variable but it only returns a value between 0 and 2 (usually 1 when playing). Anybody have an idea how to get the video frame rate?

Cheers

Answer 1

Use AVAssetTrack's nominalFrameRate property.

Below method to get FrameRate : Here queuePlayer is AVPlayer

-(float)getFrameRateFromAVPlayer
{
  float fps=0.00;
  if (self.queuePlayer.currentItem.asset) {
    AVAssetTrack * videoATrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] lastObject];
    if(videoATrack)
    {
        fps = videoATrack.nominalFrameRate;
    }
  }
  return fps;
}

Answer 2

Swift 4 version of the answer:

let asset = avplayer.currentItem.asset

let tracks = asset.tracks(withMediaType: .video)

let fps = tracks?.first?.nominalFrameRate

Remember to handle nil checking.

Answer 3

There seems to be a discrepancy in this nominalFrameRate returned for the same media played on different versions of iOS. I have a video I encoded with ffmpeg at 1 frame per second (125 frames) with keyframes every 25 frames and when loading in an app on iOS 7.x the (nominal) frame rate is 1.0, while on iOS 8.x the (nominal) frame rate is 0.99. This seems like a very small difference, however in my case I need to navigate precisely to a given frame in the movie and this difference screws up such navigation (the movie is an encoding of a sequence of presentation slides). Given that I already know the frame rate of the videos my app needs to play (e.g. 1 fps) I can simply rely on this value instead of determining the frame rate dynamically (via nominalFrameRate value), however I wonder WHY there is such discrepancy between iOS versions as far as this nominalFrameRate goes. Any ideas?