在ios中获取视频的FPS

Question

如何在 iOS 应用程序中使用 AVFoundation 获取视频的 FPS？我已经尝试了下面的代码，但它似乎不正确。

AVAssetTrack *videoAssetTrack = [myAsset tracksWithMediaType:AVMediaTypeVideo].firstObject;
NSLog(@"FPS is  : %f ",videoAssetTrack.nominalFrameRate);

Answer 1

我通过以下代码行获得了正确的 FPS：

AVAsset * myAsset = [[AVURLAsset alloc] initWithURL: _videoUrl options: nil];
AVAssetTrack * videoAssetTrack = [myAsset tracksWithMediaType: AVMediaTypeVideo].firstObject;
NSLog(@"FPS is  : %f ", videoAssetTrack.nominalFrameRate);

Answer 2

适用于 Swift 5 的 AVAsset 扩展

extension AVAsset {
   /**
    * Get FPS from AVAsset
    */
   var fps: Float? {
      self.tracks(withMediaType: .video).first?.nominalFrameRate
   }
}

Answer 3

iOS 16

您可以受益于 Swift 并发开发，通过使用

Load

属性异步检索

FPS

、

size or dimension

和 duration。

var asset: AVAsset? = AVAsset(url: filePath)
if let asset = asset,
   let videoTrack = try? await asset.loadTracks(withMediaType: .video).first {

     let size = try? await videoTrack.load(.naturalSize)
     let fps = try? await videoTrack.load(.nominalFrameRate)
     let duration = try? await asset.load(.duration)
}