AVPlayer does not fire playbackBufferEmpty but does not play either

Question

I use AVPlayer to play an audio livestream via internet. I like to recover playback if it was paused for longer than 1 minute.

I call player.rate = 1.0 to resume. However if the stream was paused for >1 minute it does not play any more. I need to recreate AVPlayerItem in this case to make it work again.

So how can I catch this case, so I know the playback did not recover?

• I tried KVO on player.rate. It stays at 1.0 though. The player is not playing!
• I tried KVO on currentItem.playbackBufferEmpty. It is not called in this case though.
• currentItem.status does not switch to .Failed. It does not change at all.

The AVPlayer just seems to do nothing in this case. Any ideas?

I build a Playground code to demonstrate the issue:

import UIKit
import AVFoundation

// keep it running forever so it plays audio
import XCPlayground
XCPSetExecutionShouldContinueIndefinitely(true)

class AVPlayerTest {

    let player = AVPlayer()
    let streamurl = NSURL(string: "http://detektor.fm/stream/mp3/musik/")!

    func startTest() {
        let item = AVPlayerItem(URL: streamurl)
        player.replaceCurrentItemWithPlayerItem(item)
        player.play()

        // give it some start time to build a buffer
        NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: #selector(timerTickedToPause), userInfo: nil, repeats: false)
    }

    @objc func timerTickedToPause(timer: NSTimer) {
        player.pause()
        // pause now for some time. 90s is not enough.
        NSTimer.scheduledTimerWithTimeInterval(120, target: self, selector: #selector(timerTickedToPlay), userInfo: nil, repeats: false)
    }

    @objc func timerTickedToPlay(timer: NSTimer) {
        // try to resume playback

        print(player.rate)

        player.play()

        print(player.rate)

        // check in some seconds if it recovered
        NSTimer.scheduledTimerWithTimeInterval(10, target: self, selector: #selector(timerTickedCheck), userInfo: nil, repeats: false)
    }

    @objc func timerTickedCheck(timer: NSTimer) {

        // it reports rate = 1.0 but is not playing here though!
        // there is no way to know for me it did not recover here!?
        print(player.rate)

        // recover by creating a new item works
        let item = AVPlayerItem(URL: streamurl)
        player.replaceCurrentItemWithPlayerItem(item)
        player.play()
    }
}

let test = AVPlayerTest()
test.startTest()

Answer 1

Use the timeControlStatus of the AVPlayer instance which "indicates whether playback is currently in progress, paused indefinitely, or suspended while waiting for appropriate network conditions."

let status = player.timeControlStatus

switch status {
case .paused:
    print("timeControlStatus.paused")

case .playing:
    print("timeControlStatus.playing")

case .waitingToPlayAtSpecifiedRate:
    print("timeControlStatus.waitingToPlayAtSpecifiedRate")
    if let reason = player.reasonForWaitingToPlay {

        switch reason {
        case .evaluatingBufferingRate:
            print("reasonForWaitingToPlay.evaluatingBufferingRate")

        case .toMinimizeStalls:
            print("reasonForWaitingToPlay.toMinimizeStalls")

        case .noItemToPlay:
            print("reasonForWaitingToPlay.noItemToPlay")

        default:
            print("Unknown \(reason)")
        }
    }

}

I have the same issue but in my case, it occurs if I go into background while in the paused state. When I come back to forground .play() does not work. It gets stuck the waitingToPlayAtSpecifiedRate.evaluatingBufferingRate mode. At that point the AVPlayerItem.status instance is readToPlay.

At this time of writing whenever a startCommand is received I reset the AVplayer to be sure. But this seems clunky. Looking for a smoother solution.