Find best camera format

  func configureSlomoCaptureFormats(formats: [AVCaptureDeviceFormat]) {
    var bestFormat: AVCaptureDeviceFormat?
    var bestFrameRateRange: AVFrameRateRange?
    
    for format in device.formats as! [AVCaptureDeviceFormat] {
      
      // We only want to use 420f media sub types to get the best dynamic range.
      let mediaSubtype = CMFormatDescriptionGetMediaSubType(format.formatDescription)
      if mediaSubtype == k420f {
//        let dimensions = CMVideoFormatDescriptionGetDimensions(format.formatDescription)
        let ranges = format.videoSupportedFrameRateRanges as! [AVFrameRateRange]
        let range = ranges.first!
        
        let someFormat = CameraFormat(format: format, range: range)
        print(someFormat)
        
        for range in format.videoSupportedFrameRateRanges as! [AVFrameRateRange] {
          
          if bestFormat == nil {
            bestFormat = format
            bestFrameRateRange = range
          }
          
          if range.maxFrameRate > bestFrameRateRange?.maxFrameRate {
            bestFormat = format
            bestFrameRateRange = range
          }
        }
      }
    }
    
  }