With AVPlayer
, after seeking to a specific time (let's say 0.5s) and calling play(), periodic observer fires few callbacks with player's currentTime()
before the seek position.
Here's the code:
- test wave file
import AVFoundation
class Player {
init() {
let session = AVAudioSession.sharedInstance()
do {
try session.setCategory(.playAndRecord, mode: .videoRecording)
try session.setActive(true)
session.requestRecordPermission { allowed in
if !allowed {
fatalError("you must allow mic access")
}
}
} catch {
fatalError(error.localizedDescription)
}
addPeriodicTimeObserver(to: player)
if let url = Bundle.main.url(forResource: "test_loop", withExtension: "wav") {
let item = AVPlayerItem(asset: AVAsset(url: url))
player.replaceCurrentItem(with: item)
}
DispatchQueue.main.asyncAfter(deadline: .now() + 3) { [weak self] in
self?.seek() {
DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
self?.play()
}
}
}
}
func addPeriodicTimeObserver(to player: AVPlayer) {
let time = CMTime(seconds: 0.04, preferredTimescale: timeScale)
_ = player.addPeriodicTimeObserver(forInterval: time, queue: .main) { [unowned self] _ in
if
self.playCalled == true &&
self.player.currentItem?.status == .readyToPlay &&
self.player.status == .readyToPlay &&
self.player.timeControlStatus == .playing {
print("currentTime \(self.player.currentTime().seconds)")
}
}
}
func seek(completion: @escaping () -> Void) {
let time = CMTime(seconds: 0.5, preferredTimescale: timeScale)
player.seek(to: time, toleranceBefore: .zero, toleranceAfter: .zero) { [unowned self] in
if $0 {
print("seek current time: \(self.player.currentTime().seconds)")
completion()
}
}
}
func play() {
if let currentItem = player.currentItem, currentItem.status == .readyToPlay {
player.play()
playCalled = true
}
}
let player = AVPlayer()
let timeScale = CMTimeScale(NSEC_PER_SEC)
var playCalled: Bool = false
}
It produces:
seek current time: 0.5
currentTime 0.475462793
currentTime 0.475983585
currentTime 0.48074996
currentTime 0.521489168
currentTime 0.561431835
currentTime 0.601529793
currentTime 0.641514043
[...]
IMPORTANT NOTE: This happens only when you run it on the device. Simulator runs are behaving as expected.
As you can see, I tried to guard myself as I could not to print any current time before it might be relevant, but still I get confusing results. Any ideas on what might the problem be and how to fix it? I would love to see the current time staring at the moment I seeked to :)