Can't able to get Video Tracks from AVURLAsset for HLS videos(.m3u8 format) for AVPlayer?

问题

I am developing a custom video player to stream HLS videos from server. I can successfully play HLS videos using AVPlayerItem and AVPlayer.

After that I want to add subtitle track and audio tracks for my video player. So I used AVMutableComposition to do so. So now the issue is when I am creating AVURLAsset for HLS Videos, I can't able to get video tracks from AVURLAsset. It is giving me always 0 tracks. I tried "loadValuesAsynchronously" of AVURLAsset and I tried adding KVO for "tracks" of AVPlayerItem. But None of these producing me any positive result.

I am using the following code.

  func playVideo() {
    let videoAsset = AVURLAsset(url: videoURL!)
    let composition = AVMutableComposition()
    // Video
    let videoTrack = composition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
    do {
        let tracks = videoAsset.tracks(withMediaType: .video)
        guard let track = tracks.first else {
            print("Can't get first video track")
            return
        }
        try videoTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: track, at: kCMTimeZero)
    } catch {
        print(error)
        return
    }
    guard let subtitlesUrl = Bundle.main.url(forResource: "en", withExtension: "vtt") else {
        print("Can't load en.vtt from bundle")
        return
    }
    //Subtitles
    let subtitleAsset = AVURLAsset(url: subtitlesUrl)
    let subtitleTrack = composition.addMutableTrack(withMediaType: .text, preferredTrackID: kCMPersistentTrackID_Invalid)
    do {
        let subTracks = subtitleAsset.tracks(withMediaType: AVMediaType.text)
        guard let subTrack = subTracks.first else {
            print("Can't get first subtitles track")
            return
        }
        try subtitleTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: subTrack, at: kCMTimeZero)
    } catch {
        print(error)
        return
    }
    // Prepare item and play it
    let item = AVPlayerItem(asset: composition)
    self.player = AVPlayer(playerItem: item)
    self.playerLayer = AVPlayerLayer.init()
    self.playerLayer.frame = self.bounds
    self.playerLayer.contentsGravity = kCAGravityResizeAspect
    self.playerLayer.player = player
    self.layer.addSublayer(self.playerLayer)
    self.player.addObserver(self, forKeyPath: "currentItem.loadedTimeRanges", options: .new, context: nil)
    self.player.play()
}

This procedure working well for .mp4 videos but not for HLS Videos(.m3u8). Anyone have some working solution for this?

or

How can we get tracks from HLS videos using AVURLAsset? If this is not possible then How can achieve similar result ?

Please let me know you feedback.

Many more thanks in advance.

回答1:

For HLS video tracks(withMediaType: .video) will return an empty array.

Use this instead: player.currentItem.presentationSize.width and player.currentItem.presentationSize.height.

Pls let me know if it works.

来源：https://stackoverflow.com/questions/52409687/cant-able-to-get-video-tracks-from-avurlasset-for-hls-videos-m3u8-format-for