我在 iOS 9/10 和 iOS 11 之间看到了不同的行为，当发生音频路由更改时(例如，您插入耳机)在 AVAudioPlayerNode 上安排 future 的缓冲区。有没有人遇到过类似的事情，你是如何解决的？请注意，我大约两周前在 Apple 的 AVFoundation 支持论坛上报告了这个问题，但收到的回复完全为零。
显示此问题的代码如下所示 - 首先简要说明:该代码是一个简单的循环，它重复安排缓冲区在将来的某个时间播放。该过程通过调用“runSequence”方法开始，该方法安排音频缓冲区在 future 某个时间播放，并将完成回调设置为嵌套方法“audioCompleteHandler”。完成回调再次调用“runSequence”方法，该方法调度另一个缓冲区并使进程永远运行。在这种情况下，除非完成处理程序正在执行，否则总是有一个缓冲区被调度。各个地方的“trace”方法是内部打印方法，仅在调试时进行打印，因此可以忽略。
在音频路由更改通知处理程序 (handleAudioRouteChange) 中，当新设备可用时(case .newDeviceAvailable)，代码会重新启动引擎和播放器，重新激活 Audio Session 并调用“runSequence”以将循环重新启动。
这一切在 iOS 9.3.5 (iPhone 5C) 和 iOS 10.3.3 (iPhone 6) 上运行良好，但在 iOS 11.1.1 (iPad Air) 上失败。失败的本质是 AVAudioPlayerNode 不播放音频而是立即调用完成处理程序。这会导致失控的情况。如果我再次删除启动循环的行(如代码所示)，它在 iOS 11.1.1 上运行良好，但在 iOS 9.3.5 和 iOS 10.3.3 上失败。这个失败是不同的:音频刚刚停止，在调试器中，我可以看到循环没有循环。
所以，一个可能的解释是，在 iOS 9.x 和 iOS 10.x 下，当音频路由发生变化时， future 的预定缓冲区是未预定的，而在 iOS 11.x 下， future 预定的缓冲区不是未预定的。
这导致两个问题:
1. 有没有人看到过类似的行为，解决方法是什么？
2. 任何人都可以向我指出在音频路由更改(或音频中断)发生时描述引擎、播放器和 session 的确切状态的文档吗？
private func runSequence() {
// For test ony
var timeBaseInfo = mach_timebase_info_data_t()
mach_timebase_info(&timeBaseInfo)
// End for test only
let audioCompleteHandler = { [unowned self] in
DispatchQueue.main.async {
trace(level: .skim, items: "Player: \(self.player1.isPlaying), Engine: \(self.engine.isRunning)")
self.player1.stop()
switch self.runStatus {
case .Run:
self.runSequence()
case .Restart:
self.runStatus = .Run
self.tickSeq.resetSequence()
//self.updateRenderHostTime()
self.runSequence()
case .Halt:
self.stopEngine()
self.player1.stop()
self.activateAudioSession(activate: false)
}
}
}
// Schedule buffer...
if self.engine.isRunning {
if let thisElem: (buffer: AVAudioPCMBuffer, duration: Int) = tickSeq.next() {
self.player1.scheduleBuffer(thisElem.buffer, at: nil, options: [], completionHandler: audioCompleteHandler)
self.player1.prepare(withFrameCount: thisElem.buffer.frameLength)
self.player1.play(at: AVAudioTime(hostTime: self.startHostTime))
self.startHostTime += AVAudioTime.hostTime(forSeconds: TimeInterval(Double(60.0 / Double(self.model.bpm.value)) * Double(thisElem.duration)))
trace(level: .skim, items:
"Samples: \(thisElem.buffer.frameLength)",
"Time: \(mach_absolute_time() * (UInt64(timeBaseInfo.numer) / UInt64(timeBaseInfo.denom))) ",
"Sample Time: \(player1.lastRenderTime!.hostTime)",
"Play At: \(self.startHostTime) ",
"Player: \(self.player1.isPlaying)",
"Engine: \(self.engine.isRunning)")
}
else {
}
}
}
@objc func handleAudioRouteChange(_ notification: Notification) {
trace(level: .skim, items: "Route change: Player: \(self.player1.isPlaying) Engine: \(self.engine.isRunning)")
guard let userInfo = notification.userInfo,
let reasonValue = userInfo[AVAudioSessionRouteChangeReasonKey] as? UInt,
let reason = AVAudioSessionRouteChangeReason(rawValue:reasonValue) else { return }
trace(level: .skim, items: audioSession.currentRoute, audioSession.mode)
trace(level: .none, items: "Reason Value: \(String(describing: userInfo[AVAudioSessionRouteChangeReasonKey] as? UInt)); Reason: \(String(describing: AVAudioSessionRouteChangeReason(rawValue:reasonValue)))")
switch reason {
case .newDeviceAvailable:
trace(level: .skim, items: "In handleAudioRouteChange.newDeviceAvailable")
for output in audioSession.currentRoute.outputs where output.portType == AVAudioSessionPortHeadphones {
startEngine()
player1.play()
activateAudioSession(activate: true)
//updateRenderHostTime()
runSequence() // <<--- Problem: works for iOS9,10; fails on iOS11. Remove it and iOS9,10 fail, works on iOS11
}
case .oldDeviceUnavailable:
trace(level: .skim, items: "In handleAudioRouteChange.oldDeviceUnavailable")
if let previousRoute =
userInfo[AVAudioSessionRouteChangePreviousRouteKey] as? AVAudioSessionRouteDescription {
for output in previousRoute.outputs where output.portType == AVAudioSessionPortHeadphones {
player1.stop()
stopEngine()
tickSeq.resetSequence()
DispatchQueue.main.async {
if let pp = self.playPause as UIButton? { pp.isSelected = false }
}
}
}
最佳答案
因此，通过进一步挖掘/测试解决了问题:
下面的代码适用于我的 iOS 9.3.5 (iPhone 5C)、iOS 10.3.3 (iPhone 6) 和 iOS 11.1.1 (iPad Air) 的测试设备(但我仍然感到困扰，因为我找不到任何先验关于如何正确处理路线变化的评论，肯定有数百人遇到过这个问题..?? 通常，当我找不到关于某个主题的任何先前评论时，我认为我做错了什么或只是不明白……哦，好吧……):
@objc func handleAudioRouteChange(_ notification: Notification) {
guard let userInfo = notification.userInfo,
let reasonValue = userInfo[AVAudioSessionRouteChangeReasonKey] as? UInt,
let reason = AVAudioSessionRouteChangeReason(rawValue:reasonValue) else { return }
switch reason {
case .newDeviceAvailable:
for output in audioSession.currentRoute.outputs where output.portType == AVAudioSessionPortHeadphones {
headphonesConnected = true
}
startEngine() // Do this regardless of whether engine.isRunning == true
if let lrt = player.lastRenderTime, let st = player.playerTime(forNodeTime: lrt)?.sampleTime {
playSampleOffset += st // Accumulate so that multiple inserts/removals move the play point forward
stopPlayer()
scheduleSegment(file: playFile, at: nil, player: player, start: playSampleOffset, length: AVAudioFrameCount(playFile.length - playSampleOffset))
startPlayer()
}
else {
// Unknown problem with getting sampleTime; reset engine, player(s), restart as appropriate
}
case .oldDeviceUnavailable:
if let previousRoute =
userInfo[AVAudioSessionRouteChangePreviousRouteKey] as? AVAudioSessionRouteDescription {
for output in previousRoute.outputs where output.portType == AVAudioSessionPortHeadphones {
headphonesConnected = false
}
}
startEngine() // Do this regardless of whether engine.isRunning == true
if let lrt = player.lastRenderTime, let st = player.playerTime(forNodeTime: lrt)?.sampleTime {
playSampleOffset += st // Accumulate...
stopPlayer()
scheduleSegment(file: playFile, at: nil, player: player, start: playSampleOffset, length: AVAudioFrameCount(playFile.length - playSampleOffset))
startPlayer() // Test only, in reality don't restart here; set play control to allow user to start audio
}
else {
// Unknown problem with getting sampleTime; reset engine, player(s), restart as appropriate
}
...
关于ios11 - AVAudioPlayerNode 调度缓冲区和 iOS11 中的音频路由更改，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47567882/