swift 为什么AVPlayer先下载而不是直播?

oxiaedzo  于 2023-06-04  发布在  Swift
关注(0)|答案(2)|浏览(472)

我第一次使用AVPlayer,我想用HTTP请求播放一个MP3文件。我使用的AVPlayer可以很好地播放mp3文件,但问题是AVPlayer需要先下载mp3,然后再播放。我不知道为什么AVPlayer下载文件,然后播放它,而不是现场播放。我的Xcode 8.2.1和我使用的Swift 3。
这是我的代码片段。

var audioPlayer = AVPlayer()
var avplayerItem : AVPlayerItem?

override func viewDidLoad() {
    super.viewDidLoad()

    let fileurl:URL = URL(string : "http://www.noiseaddicts.com/samples_1w72b820/2514.mp3")!
    avplayerItem = AVPlayerItem(url : fileurl)
    audioPlayer = AVPlayer(playerItem : avplayerItem)
    audioPlayer.rate = 1.0
    audioPlayer.play()
}

如果AVPlayer需要下载整个文件才能播放,音频直播应该怎么做?
谢谢

m3eecexj

m3eecexj1#

你基本上是使用mp3作为容器来在整个互联网上传输你的音频,所以播放器必须全部下载,如果你想使它有效或避免下载的延迟,你必须使用HLSDASHCMAFWebRTC来传输它,所以播放器将按块下载它,并在下载时播放它,类似于Spotify或苹果音乐的东西。

tvz2xvvm

tvz2xvvm2#

另外编辑:Luaan也是对的。* 直播需要服务器支持-至少能够进行部分下载。其他播放器是否允许使用该URL进行直播?* ”您还应该尝试使用未定义持续时间的声音URL。
你有没有试过把它当作一个未定义持续时间的音频流?

avplayerItem = CachingPlayerItem(url: url, recordingName: recordingName ?? "default.mp3")

CachingPlayerItem将从URL准备AVURLAset。

init(url: URL, customFileExtension: String?, recordingName: String) {
    guard let components = URLComponents(url: url, resolvingAgainstBaseURL: false),
    let scheme = components.scheme,
    var urlWithCustomScheme = url.withScheme(cachingPlayerItemScheme) else {
    fatalError("Urls without a scheme are not supported")
    }
    self.recordingName = recordingName
    self.url = url
    self.initialScheme = scheme
    if let ext = customFileExtension {
    urlWithCustomScheme.deletePathExtension()
    urlWithCustomScheme.appendPathExtension(ext)
    self.customFileExtension = ext
    }
    let asset = AVURLAsset(url: urlWithCustomScheme)
    asset.resourceLoader.setDelegate(resourceLoaderDelegate, queue: DispatchQueue.main)
    super.init(asset: asset, automaticallyLoadedAssetKeys: nil)
    resourceLoaderDelegate.owner = self
    addObserver(self, forKeyPath: "status", options: NSKeyValueObservingOptions.new, context: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(playbackStalledHandler), name:NSNotification.Name.AVPlayerItemPlaybackStalled, object: self)
    }

初始化AVPlayerItem后,从中创建一个AVPlayer对象,以便它可以启动从给定URL加载音频流的过程:

player = AVPlayer(playerItem: playerItem)
player.automaticallyWaitsToMinimizeStalling = false

func resourceLoader(_ resourceLoader: AVAssetResourceLoader, shouldWaitForLoadingOfRequestedResource loadingRequest: AVAssetResourceLoadingRequest) -> Bool {
if playingFromData {
// Nothing to load.
} else if session == nil {
// If we're playing from a url, we need to download the file.
// We start loading the file on first request only.
guard let initialUrl = owner?.url else {
fatalError("internal inconsistency")
}
startDataRequest(with: initialUrl)
}
pendingRequests.insert(loadingRequest)
processPendingRequests()
return true
}

安装资源后:

func startDataRequest(with url: URL) {
var recordingName = "default.mp3"
if let recording = owner?.recordingName{
recordingName = recording
}
fileURL = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
.appendingPathComponent(recordingName)
let configuration = URLSessionConfiguration.default
configuration.requestCachePolicy = .reloadIgnoringLocalAndRemoteCacheData
session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
session?.dataTask(with: url).resume()
outputStream = OutputStream(url: fileURL, append: true)
outputStream?.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
outputStream?.open()
}

然后,开始将数据字节接收到delegate函数中:

func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data)

现在您已经开始接收实时音频流。

func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
let bytesWritten = data.withUnsafeBytes{outputStream?.write($0, maxLength: data.count)}
print("bytes written :\(bytesWritten!) to \(fileURL)")
}

现在创建一个OutputStream对象,打开它,然后附加我们在上面的delegate函数中接收到的字节,就是这样,我们保存了实时音频流的所需部分。
来源:Medium Article, Mohan Pandey

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