Looping an AVPlayer video stream and refreshing the bitrate on each loop

Question

I'm looping my streamed videos (not live stream) via .m3u8 playlist and each time the video restarts, it plays the video with the same bitrate adapting that occurs the first time you watch the video (bad quality -> good quality). Is there a way to refresh the stream quality each time the video loops so that the beginning gets replaced with the higher-rate bitrate seamlessly? Instead of just re-playing what was initially loaded?

Michael Gaylord Michael Gaylord · Accepted Answer · 2016-07-04T15:42:12

Apple's AVPlayer attempts to load the first stream listed in the HLS playlist. So if you want the highest quality stream to be loaded first by default, you need to specify it as the first stream in the playlist file.

With that in mind, one way of achieving what you need to achieve is to have a different m3u8 file for each of your streams. For example, if you have a three variant stream playlist, you would have three .m3u8 playlists.

Then in your view controller where you are using your AVPlayer, you need to keep a reference to the last observed bitrate and most recent bit rate:

var lastObservedBitrate: double = 0
var mostRecentBitrate: double = 0

You would then need to register a notification observer on your player with notification name: AVPlayerItemNewAccessLogEntryNotification

NSNotificationCenter.defaultCenter().addObserver(self, selector:#selector(MyViewController.accessEventLog(_:)), name: AVPlayerItemNewAccessLogEntryNotification, object: nil)

Whenever the access log is updated, you can then inspect the bitrate and stream used using the following code:

func accessLogEvent(notification: NSNotification) {
    guard let item = notification.object as? AVPlayerItem,
        accessLog = item.accessLog() else {
            return
    }
    accessLog.events.forEach { lastEvent in
        let bitrate = lastEvent.indicatedBitrate
        lastObservedBitrate = lastEvent.observedBitrate
        if let mostRecentBitrate = self.mostRecentBitrate where bitrate != mostRecentBitrate {
            self.mostRecentBitrate = bitrate
        }
    }    
}

Whenever your player loops, you can load the appropriate m3u8 file based on your lastObservedBitrate. So if your lastObservedBitrate is 2500 kbps, you would load your m3u8 file that has the 2500kbps stream at the top of the file.

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Looping an AVPlayer video stream and refreshing the bitrate on each loop

1 Answers