Swift - 检查 url 资产是否有声音

Question

我的屏幕裂了，我的手机没有声音功能。我用相机录制了一段视频。当我从didFinishPickingMediaWithInfo 选择视频网址时，我试图检查视频是否有声音，但player.currentItem?.asset.tracks 说视频确实有声音（设备和录制的视频肯定没有声音）。

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {

   // ...
   guard let url = info[UIImagePickerController.InfoKey.mediaURL] as? URL else { return }

   // ...
   let asset = AVURLAsset(url: url)
   let playerItem = AVPlayerItem(asset: asset)
   let player = AVPlayer(playerItem: playerItem)

   if let tracks = player.currentItem?.asset.tracks {
                
       switch tracks.count {
       case 0:
           print("tracks -0: audio only")
                    
       case 1:
           print("tracks -1: video only ")

       case 2:
           print("tracks -2: audio and video") // this prints when the video does have sound (recorded before the screen cracked)
                    
       default:
           print("tracks -default: audio and video") // *** this always prints when the video doesn't have sound (recorded after the screen cracked) ***       
       }   
   }
}

Answer 1

这是这样做的方法：

let asset = AVURLAsset(url: url)
// if using a mixComposition it's: let asset = mixComposition (an AVMutableComposition itself is an asset)

let audioTrack = asset.tracks(withMediaType: .audio)
if audioTrack.isEmpty {

    print("this video has no sound")

} else {

    print("this video has sound")
}