How to buffer audio using AVPlayer in iOS? - ios

Question

I want to play stream audio from the Internet. I wrote code that plays stream but it don't have any buffer so if signal is weak application stop playing audio. This is my code:
import UIKit
import AVFoundation
import MediaPlayer
import AudioToolbox
class ViewController: UIViewController {
var playerItem:AVPlayerItem?
var player:AVPlayer?
#IBOutlet weak var PlayButton: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
var buffer = AVAudioBuffer ()
let url = NSURL (string: "http://radio.afera.com.pl/afera64.aac")
playerItem = AVPlayerItem(URL: url!)
player = AVPlayer(playerItem: playerItem!)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func PlayButtonTapped(sender: AnyObject)
{
if ((player!.rate != 0) && (player!.error == nil))
{
player!.pause()
PlayButton.setImage(UIImage(named:"Play"), forState: UIControlState.Normal)
}
else
{
player!.play()
PlayButton.setImage(UIImage(named:"Stop"), forState:UIControlState.Normal)
}
}
}
I have no idea how to buffer this stream. I searched apple documentation but can't find anything in Swift.
I find something like AVAudioBuffer but I don't know how to use it, and if its correct to resolve this problem.
P.S. C# have documentation on MSDN, is something similar on Apple in case of Swift?

Answer 1

The answer is in creating an error delegate that launched a selector every time the player stopped (The error changes when the network connection is interrupted or the stream didn't load properly):
Here are delegates, just outside and above my RadioPlayer class:
protocol errorMessageDelegate {
func errorMessageChanged(newVal: String)
}
class:
import Foundation
import AVFoundation
import UIKit
class RadioPlayer : NSObject {
static let sharedInstance = RadioPlayer()
var instanceDelegate:sharedInstanceDelegate? = nil
var sharedInstanceBool = false {
didSet {
if let delegate = self.instanceDelegate {
delegate.sharedInstanceChanged(self.sharedInstanceBool)
}
}
}
private var player = AVPlayer(URL: NSURL(string: Globals.radioURL)!)
private var playerItem = AVPlayerItem?()
private var isPlaying = false
var errorDelegate:errorMessageDelegate? = nil
var errorMessage = "" {
didSet {
if let delegate = self.errorDelegate {
delegate.errorMessageChanged(self.errorMessage)
}
}
}
override init() {
super.init()
errorMessage = ""
let asset: AVURLAsset = AVURLAsset(URL: NSURL(string: Globals.radioURL)!, options: nil)
let statusKey = "tracks"
asset.loadValuesAsynchronouslyForKeys([statusKey], completionHandler: {
var error: NSError? = nil
dispatch_async(dispatch_get_main_queue(), {
let status: AVKeyValueStatus = asset.statusOfValueForKey(statusKey, error: &error)
if status == AVKeyValueStatus.Loaded{
let playerItem = AVPlayerItem(asset: asset)
self.player = AVPlayer(playerItem: playerItem)
self.sharedInstanceBool = true
} else {
self.errorMessage = error!.localizedDescription
print(error!)
}
})
})
NSNotificationCenter.defaultCenter().addObserverForName(
AVPlayerItemFailedToPlayToEndTimeNotification,
object: nil,
queue: nil,
usingBlock: { notification in
print("Status: Failed to continue")
self.errorMessage = "Stream was interrupted"
})
print("Initializing new player")
}
func resetPlayer() {
errorMessage = ""
let asset: AVURLAsset = AVURLAsset(URL: NSURL(string: Globals.radioURL)!, options: nil)
let statusKey = "tracks"
asset.loadValuesAsynchronouslyForKeys([statusKey], completionHandler: {
var error: NSError? = nil
dispatch_async(dispatch_get_main_queue(), {
let status: AVKeyValueStatus = asset.statusOfValueForKey(statusKey, error: &error)
if status == AVKeyValueStatus.Loaded{
let playerItem = AVPlayerItem(asset: asset)
//playerItem.addObserver(self, forKeyPath: "status", options: NSKeyValueObservingOptions.New, context: &ItemStatusContext)
self.player = AVPlayer(playerItem: playerItem)
self.sharedInstanceBool = true
} else {
self.errorMessage = error!.localizedDescription
print(error!)
}
})
})
}
func bufferFull() -> Bool {
return bufferAvailableSeconds() > 45.0
}
func bufferAvailableSeconds() -> NSTimeInterval {
// Check if there is a player instance
if ((player.currentItem) != nil) {
// Get current AVPlayerItem
let item: AVPlayerItem = player.currentItem!
if (item.status == AVPlayerItemStatus.ReadyToPlay) {
let timeRangeArray: NSArray = item.loadedTimeRanges
if timeRangeArray.count < 1 { return(CMTimeGetSeconds(kCMTimeInvalid)) }
let aTimeRange: CMTimeRange = timeRangeArray.objectAtIndex(0).CMTimeRangeValue
//let startTime = CMTimeGetSeconds(aTimeRange.end)
let loadedDuration = CMTimeGetSeconds(aTimeRange.duration)
return (NSTimeInterval)(loadedDuration);
}
else {
return(CMTimeGetSeconds(kCMTimeInvalid))
}
}
else {
return(CMTimeGetSeconds(kCMTimeInvalid))
}
}
func play() {
player.play()
isPlaying = true
print("Radio is \(isPlaying ? "" : "not ")playing")
}
func pause() {
player.pause()
isPlaying = false
print("Radio is \(isPlaying ? "" : "not ")playing")
}
func currentlyPlaying() -> Bool {
return isPlaying
}
}
protocol sharedInstanceDelegate {
func sharedInstanceChanged(newVal: Bool)
}
RadioViewController:
import UIKit
import AVFoundation
class RadioViewController: UIViewController, errorMessageDelegate, sharedInstanceDelegate {
// MARK: Properties
var firstErrorSkip = true
var firstInstanceSkip = true
#IBOutlet weak var listenLabel: UILabel!
#IBOutlet weak var radioSwitch: UIImageView!
#IBAction func back(sender: AnyObject) {
print("Dismissing radio view")
if let navigationController = self.navigationController
{
navigationController.popViewControllerAnimated(true)
}
}
#IBAction func switched(sender: AnyObject) {
toggle()
}
override func viewDidLoad() {
super.viewDidLoad()
do {
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
print("AVAudioSession Category Playback OK")
do {
try AVAudioSession.sharedInstance().setActive(true)
print("AVAudioSession is Active")
} catch let error as NSError {
print(error.localizedDescription)
}
} catch let error as NSError {
print(error.localizedDescription)
}
RadioPlayer.sharedInstance.errorDelegate = self
RadioPlayer.sharedInstance.instanceDelegate = self
if RadioPlayer.sharedInstance.currentlyPlaying() {
radioSwitch.image = UIImage(named: "Radio_Switch_Active")
listenLabel.text = "Click to Pause Radio Stream:"
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func toggle() {
if RadioPlayer.sharedInstance.currentlyPlaying() {
pauseRadio()
} else {
playRadio()
}
}
func playRadio() {
firstErrorSkip = false
firstInstanceSkip = false
if RadioPlayer.sharedInstance.errorMessage != "" || RadioPlayer.sharedInstance.bufferFull() {
resetStream()
} else {
radioSwitch.image = UIImage(named: "Radio_Switch_Active")
listenLabel.text = "Click to Pause Radio Stream:"
RadioPlayer.sharedInstance.play()
}
}
func pauseRadio() {
RadioPlayer.sharedInstance.pause()
radioSwitch.image = UIImage(named: "Radio_Switch_Inactive")
listenLabel.text = "Click to Play Radio Stream:"
}
func resetStream() {
print("Reloading interrupted stream");
RadioPlayer.sharedInstance.resetPlayer()
//RadioPlayer.sharedInstance = RadioPlayer();
RadioPlayer.sharedInstance.errorDelegate = self
RadioPlayer.sharedInstance.instanceDelegate = self
if RadioPlayer.sharedInstance.bufferFull() {
radioSwitch.image = UIImage(named: "Radio_Switch_Active")
listenLabel.text = "Click to Pause Radio Stream:"
RadioPlayer.sharedInstance.play()
} else {
playRadio()
}
}
func errorMessageChanged(newVal: String) {
if !firstErrorSkip {
print("Error changed to '\(newVal)'")
if RadioPlayer.sharedInstance.errorMessage != "" {
print("Showing Error Message")
let alertController = UIAlertController(title: "Stream Failure", message: RadioPlayer.sharedInstance.errorMessage, preferredStyle: UIAlertControllerStyle.Alert)
alertController.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.Default, handler: nil))
self.presentViewController(alertController, animated: true, completion: nil)
pauseRadio()
}
} else {
print("Skipping first init")
firstErrorSkip = false
}
}
func sharedInstanceChanged(newVal: Bool) {
if !firstInstanceSkip {
print("Detected New Instance")
if newVal {
RadioPlayer.sharedInstance.play()
}
} else {
firstInstanceSkip = false
}
}
}
Hope this will help :)

Answer 2

change
playerItem = AVPlayerItem?()
to
playerItem:AVPlayerItem?