我有以下使用 AVAudioPlayerNode 播放音频文件的 Swift Playground 代码。
import AVFoundation
import Foundation
NSSetUncaughtExceptionHandler { exception in
print("Exception thrown: \(exception)")
}
var filePath = "/Users/fractor/Desktop/TestFile.mp3"
let file : AVAudioFile
do {
file = try AVAudioFile(forReading: URL(fileURLWithPath: filePath))
} catch let error {
print(error.localizedDescription)
throw error
}
let audioEngine = AVAudioEngine()
let playerNode = AVAudioPlayerNode()
audioEngine.attach(playerNode)
audioEngine.connect(playerNode, to: audioEngine.outputNode, format: file.processingFormat);
do {
try audioEngine.start()
} catch let error {
print(error.localizedDescription)
throw error
}
playerNode.scheduleFile(file, at: nil){}
playerNode.play();
当使用内置扬声器或连接到 UE WONDERBOOM 蓝牙扬声器时，这在我的 mac mini 上运行良好。但是，当连接到 UE BOOM 2 蓝牙扬声器时，它会崩溃。
AVAudioPlayer我尝试过的所有扬声器都可以正常使用，包括 UE BOOM 2 。
异常消息是“当引擎未运行时播放器启动”但是插入打印命令显示引擎在playerNode.play()被调用之前正在运行。
这是堆栈跟踪的（部分）。
在这种情况下，EXC_BAD_INSTRUCTION 表示什么？
为了消除由于使用 Swift 游乐场而引入错误行为的可能性，我还创建了一个 Swift macOS Cocoa 应用程序。这是代码：
class ViewController: NSViewController {
let filePath = "/Users/fractor/Desktop/TestFile.mp3"
var file : AVAudioFile?
var audioEngine = AVAudioEngine()
var playerNode = AVAudioPlayerNode()
override func viewDidLoad() {
super.viewDidLoad()
do {
file = try AVAudioFile(forReading: URL(fileURLWithPath: filePath))
} catch let error {
print(error.localizedDescription)
return
}
audioEngine.attach(playerNode)
audioEngine.connect(playerNode, to: audioEngine.outputNode, format: file!.processingFormat);
do {
try audioEngine.start()
} catch let error {
print(error.localizedDescription)
return
}
playerNode.scheduleFile(file!, at: nil){}
print("audioEngine.isRunning = \(audioEngine.isRunning)");
playerNode.play();
print("playerNode.isPlaying = \(playerNode.isPlaying)");
}
}
当连接到 UE BOOM 2 扬声器时无法播放，并出现以下错误：
2019-07-23 13:32:50.784444+0100 AVAudioPlayerNodeSwiftTest[1757:29297] [AudioHAL_Client] HALC_ProxyIOContext.cpp:958:IOWorkLoop: HALC_ProxyIOContext::IOWorkLoop: the server failed to start, Error: 0xE00002D6
2019-07-23 13:32:51.696089+0100 AVAudioPlayerNodeSwiftTest[1757:29249] Failed to set (contentViewController) user defined inspected property on (NSWindow): player started when engine not running
2019-07-23 13:32:53.815222+0100 AVAudioPlayerNodeSwiftTest[1757:29448] [AudioHAL_Client] HALC_ProxyIOContext.cpp:958:IOWorkLoop: HALC_ProxyIOContext::IOWorkLoop: the server failed to start, Error: 0xE00002D6
这同样适用于 WONDERBOOM 扬声器和内置扬声器。
play如果我使用以下代码调用后台线程，我设法获得异常跟踪：
DispatchQueue.global(qos: .background).async {
print("audioEngine.isRunning = \(self.audioEngine.isRunning)");
self.playerNode.play();
print("playerNode.isPlaying = \(self.playerNode.isPlaying)");
}
完整的输出是：
audioEngine.isRunning = true
2019-07-24 12:25:38.710647+0100 AVAudioPlayerNodeSwiftTest[1852:21353] [AudioHAL_Client] HALC_ProxyIOContext.cpp:958:IOWorkLoop: HALC_ProxyIOContext::IOWorkLoop: the server failed to start, Error: 0xE00002D6
2019-07-24 12:25:40.717683+0100 AVAudioPlayerNodeSwiftTest[1852:21340] [General] An uncaught exception was raised
2019-07-24 12:25:40.717738+0100 AVAudioPlayerNodeSwiftTest[1852:21340] [General] player started when engine not running
2019-07-24 12:25:40.717865+0100 AVAudioPlayerNodeSwiftTest[1852:21340] [General] (
0 CoreFoundation 0x00007fff2d017cfd __exceptionPreprocess + 256
1 libobjc.A.dylib 0x00007fff576bea17 objc_exception_throw + 48
2 CoreFoundation 0x00007fff2d032a1a +[NSException raise:format:arguments:] + 98
3 AVFAudio 0x00007fff291f2304 _Z19AVAE_RaiseExceptionP8NSStringz + 156
4 AVFAudio 0x00007fff29247d8c _ZN21AVAudioPlayerNodeImpl9StartImplEP11AVAudioTime + 1282
5 AVFAudio 0x00007fff29246b48 -[AVAudioPlayerNode play] + 75
6 AVAudioPlayerNodeSwiftTest 0x0000000100002924 $s26AVAudioPlayerNodeSwiftTest14ViewControllerC11viewDidLoadyyFyycfU0_ + 644
7 AVAudioPlayerNodeSwiftTest 0x0000000100002b8d $s26AVAudioPlayerNodeSwiftTest14ViewControllerC11viewDidLoadyyFyycfU0_TA + 13
8 AVAudioPlayerNodeSwiftTest 0x00000001000025dd $sIeg_IeyB_TR + 45
9 libdispatch.dylib 0x000000010034fe7c _dispatch_call_block_and_release + 12
10 libdispatch.dylib 0x0000000100350f1b _dispatch_client_callout + 8
11 libdispatch.dylib 0x0000000100363a06 _dispatch_root_queue_drain + 816
12 libdispatch.dylib 0x00000001003642da _dispatch_worker_thread2 + 125
13 libsystem_pthread.dylib 0x00000001003ca0b7 _pthread_wqthread + 583
14 libsystem_pthread.dylib 0x00000001003c9e01 start_wqthread + 13
)
2019-07-24 12:25:40.718570+0100 AVAudioPlayerNodeSwiftTest[1852:21340] *** Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'player started when engine not running'
*** First throw call stack:
(
0 CoreFoundation 0x00007fff2d017cfd __exceptionPreprocess + 256
1 libobjc.A.dylib 0x00007fff576bea17 objc_exception_throw + 48
2 CoreFoundation 0x00007fff2d032a1a +[NSException raise:format:arguments:] + 98
3 AVFAudio 0x00007fff291f2304 _Z19AVAE_RaiseExceptionP8NSStringz + 156
4 AVFAudio 0x00007fff29247d8c _ZN21AVAudioPlayerNodeImpl9StartImplEP11AVAudioTime + 1282
5 AVFAudio 0x00007fff29246b48 -[AVAudioPlayerNode play] + 75
6 AVAudioPlayerNodeSwiftTest 0x0000000100002924 $s26AVAudioPlayerNodeSwiftTest14ViewControllerC11viewDidLoadyyFyycfU0_ + 644
7 AVAudioPlayerNodeSwiftTest 0x0000000100002b8d $s26AVAudioPlayerNodeSwiftTest14ViewControllerC11viewDidLoadyyFyycfU0_TA + 13
8 AVAudioPlayerNodeSwiftTest 0x00000001000025dd $sIeg_IeyB_TR + 45
9 libdispatch.dylib 0x000000010034fe7c _dispatch_call_block_and_release + 12
10 libdispatch.dylib 0x0000000100350f1b _dispatch_client_callout + 8
11 libdispatch.dylib 0x0000000100363a06 _dispatch_root_queue_drain + 816
12 libdispatch.dylib 0x00000001003642da _dispatch_worker_thread2 + 125
13 libsystem_pthread.dylib 0x00000001003ca0b7 _pthread_wqthread + 583
14 libsystem_pthread.dylib 0x00000001003c9e01 start_wqthread + 13
)
libc++abi.dylib: terminating with uncaught exception of type NSException
同样，如果使用 WONDERBOOM 或内置扬声器也没问题。
人们在这里也遇到了问题：https ://forums.developer.apple.com/thread/118459
AudioKit 也崩溃：AudioKit macOS HelloWorld 与 UE BOOM 2 扬声器崩溃
AVAudioPlayer对于我正在开发的应用程序来说是不够的。问题是什么？想必既然它抛出了一个异常，那就是Apple代码中的一个错误？