iOS 确定视频中的帧数

Question

如果我在 Swift 中有一个 MPMoviePlayerController:

MPMoviePlayerController mp = MPMoviePlayerController(contentURL: url)

有什么方法可以获取位于 url 的视频中的帧数？如果不是，是否有其他方法可以确定帧数？

Answer 1

我觉得MPMoviePlayerController帮不了你。

使用 AVAssetReader 并计算 CMSampleBuffer 的数量 returns 给你。您可以将其配置为甚至不解码帧，有效地解析文件，因此它应该速度快且内存效率高。

类似

    var asset = AVURLAsset(URL: url, options: nil)
    var reader = AVAssetReader(asset: asset, error: nil)
    var videoTrack = asset.tracksWithMediaType(AVMediaTypeVideo)[0] as! AVAssetTrack

    var readerOutput = AVAssetReaderTrackOutput(track: videoTrack, outputSettings: nil) // NB: nil, should give you raw frames
    reader.addOutput(readerOutput)
    reader.startReading()

    var nFrames = 0

    while true {
        var sampleBuffer = readerOutput.copyNextSampleBuffer()
        if sampleBuffer == nil {
            break
        }

        nFrames++
    }

    println("Num frames: \(nFrames)")

抱歉，如果这不是惯用的，我不知道 swift。

Answer 2

Swift 5

 func getNumberOfFrames(url: URL) -> Int {
        let asset = AVURLAsset(url: url, options: nil)
        do {
            let reader = try AVAssetReader(asset: asset)
        //AVAssetReader(asset: asset, error: nil)
            let videoTrack = asset.tracks(withMediaType: AVMediaType.video)[0]

            let readerOutput = AVAssetReaderTrackOutput(track: videoTrack, outputSettings: nil) // NB: nil, should give you raw frames
            reader.add(readerOutput)
        reader.startReading()

        var nFrames = 0

        while true {
            let sampleBuffer = readerOutput.copyNextSampleBuffer()
            if sampleBuffer == nil {
                break
            }

            nFrames = nFrames+1
        }

        print("Num frames: \(nFrames)")
            return nFrames
        }catch {
            print("Error: \(error)")
        }
        return 0
    }

Answer 3

您也可以使用每秒帧数来计算总帧数。

var player: AVPlayer?
var playerController = AVPlayerViewController()
var videoFPS: Int = 0
var totalFrames: Int?


guard let videoURL = "" else { return }
player = AVPlayer(url: videoURL)
playerController.player = player
guard player?.currentItem?.asset != nil else {
    return
}
let asset = self.player?.currentItem?.asset
let tracks = asset!.tracks(withMediaType: .video)
let fps = tracks.first?.nominalFrameRate
let duration = self.player?.currentItem?.duration

self.videoFPS = lround(Double(fps!))
self.totalFrames = lround(Double(self!.videoFPS) * durationSeconds)

iOS 确定视频中的帧数

iOS Determine Number of Frames in Video

video

video-processing

mpmovieplayercontroller

ios

swift