iphone - iPhone 3GS iOS 4.0.1 下的 MPMoviePlayerController thumbnailImageAtTime EXC_BAD_ACCESS

Question

最近几天我在运行 iOS 4.0.1 的 iPhone 3GS 下遇到了一个非常奇怪和具体的问题。

我有一个 UIImagePicker，而用户可以选择图片或视频文件。之后，我从该媒体源生成缩略图。对于图片，它工作正常，但是，对于视频，我总是在调用 thumbnailImageAtTime 方法后得到一个 EXC_BAD_ACCESS。

这是我正在使用的代码:

NSURL* contentURL = [NSURL URLWithString:_videoFilePath];
_moviePlayerController = [[MPMoviePlayerController alloc] initWithContentURL:contentURL];
[_moviePlayerController setShouldAutoplay:NO];
[_moviePlayerController setCurrentPlaybackTime:(NSTimeInterval)1];
[_moviePlayerController setInitialPlaybackTime:(NSTimeInterval)1];
[_moviePlayerController setControlStyle:MPMovieControlStyleNone];
[_moviePlayerController setMovieControlMode:MPMovieControlStyleNone];
videoThumb = [[_moviePlayerController thumbnailImageAtTime:(NSTimeInterval)1 timeOption:MPMovieTimeOptionNearestKeyFrame] retain];
[_moviePlayerController setCurrentPlaybackTime:(NSTimeInterval)-1];
[_moviePlayerController stop];
[_moviePlayerController release];

以上代码通过 NSOperationQueue 在单独的线程上运行。我可以让多个缩略图生成请求排队，但在任何给定时间只能运行一个。该队列配置了一个 maxConcurrentOperationCount 为 1

根据我能够进行的测试，这个问题只发生在 iOS 4.0.1 上。运行 iOS 4.0、4.1、4.2 和 4.2.1 不会重现此类错误。我也不能 @try @catch 这个错误。

有人知道或知道这可能是什么吗？或者要寻找什么？我已经为此苦苦挣扎了好几天。

Date/Time:       2011-02-06 11:14:01 -0200
OS Version:      iPhone OS 4.0.1 (8A293)
Report Version:  104

Exception Type:  SIGBUS
Exception Codes: BUS_ADRALN at 0x2c
Crashed Thread:  0

Thread 0 Crashed:
0   MediaToolbox                        0x0003b6b0 FigMediaValidatorCopyByteStream + 4
1   Celestial                           0x00014c35 -[AVFileValidator notificationForFileCheckResult:] + 281
2   Celestial                           0x000146fb -[AVFileValidator postNotificationForCallback:] + 35
3   CoreFoundation                      0x000277ff -[NSObject(NSObject) performSelector:withObject:] + 23
4   Celestial                           0x000094a5 -[AVObjectRegistry safeInvokeWithDescription:] + 125
5   CoreFoundation                      0x000277ff -[NSObject(NSObject) performSelector:withObject:] + 23
6   Foundation                          0x00090bbd __NSThreadPerformPerform + 269
7   CoreFoundation                      0x00071a8d __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 13
8   CoreFoundation                      0x0007376f __CFRunLoopDoSources0 + 383
9   CoreFoundation                      0x0007450b __CFRunLoopRun + 231
10  CoreFoundation                      0x0001d8eb CFRunLoopRunSpecific + 231
11  CoreFoundation                      0x0001d7f3 CFRunLoopRunInMode + 59
12  GraphicsServices                    0x000036ef GSEventRunModal + 115
13  GraphicsServices                    0x0000379b GSEventRun + 63
14  UIKit                               0x000062a7 -[UIApplication _run] + 403
15  UIKit                               0x00004e17 UIApplicationMain + 671
16  App                                 0x000035ef 0x1000 + 9711

Thread 1:
0   libSystem.B.dylib                   0x0002dc4c kevent + 24
1   libSystem.B.dylib                   0x000d689c _dispatch_queue_invoke + 104
2   libSystem.B.dylib                   0x000d6a3c _dispatch_worker_thread2 + 128
3   libSystem.B.dylib                   0x0007ad89 _pthread_wqthread + 265

Thread 2:
0   libSystem.B.dylib                   0x00001658 mach_msg_trap + 20
1   CoreFoundation                      0x000722cf __CFRunLoopServiceMachPort + 95
2   CoreFoundation                      0x00074589 __CFRunLoopRun + 357
3   CoreFoundation                      0x0001d8eb CFRunLoopRunSpecific + 231
4   CoreFoundation                      0x0001d7f3 CFRunLoopRunInMode + 59
5   WebCore                             0x0000305d RunWebThread(void*) + 369
6   libSystem.B.dylib                   0x0007a98d _pthread_start + 249

Thread 3:
0   libSystem.B.dylib                   0x00001658 mach_msg_trap + 20
1   CoreFoundation                      0x000722cf __CFRunLoopServiceMachPort + 95
2   CoreFoundation                      0x00074589 __CFRunLoopRun + 357
3   CoreFoundation                      0x0001d8eb CFRunLoopRunSpecific + 231
4   CoreFoundation                      0x0001d7f3 CFRunLoopRunInMode + 59
5   Foundation                          0x0003b725 +[NSURLConnection(NSURLConnectionReallyInternal) _resourceLoadLoop:] + 213
6   Foundation                          0x0000bc9d -[NSThread main] + 45
7   Foundation                          0x000909e1 __NSThread__main__ + 973
8   libSystem.B.dylib                   0x0007a98d _pthread_start + 249

Thread 4:
0   libSystem.B.dylib                   0x00025a20 select$DARWIN_EXTSN + 20
1   libSystem.B.dylib                   0x0007a98d _pthread_start + 249

Thread 5:
0   libSystem.B.dylib                   0x000798dc __semwait_signal + 24
1   libSystem.B.dylib                   0x0002e639 pthread_cond_wait + 33
2   CoreMedia                           0x00002f1b WaitOnCondition + 11
3   CoreMedia                           0x00002e61 FigSemaphoreWaitRelative + 73
4   MediaToolbox                        0x00003e4b fpa_AsyncMovieControlThread + 55
5   CoreMedia                           0x0001e4c3 figThreadMain + 139
6   libSystem.B.dylib                   0x0007a98d _pthread_start + 249

Thread 6:
0   libSystem.B.dylib                   0x00001658 mach_msg_trap + 20
1   MediaToolbox                        0x00008b0b FigExpressNotificationThread + 43
2   CoreMedia                           0x0001e4c3 figThreadMain + 139
3   libSystem.B.dylib                   0x0007a98d _pthread_start + 249

Thread 7:
0   libSystem.B.dylib                   0x000798dc __semwait_signal + 24
1   libSystem.B.dylib                   0x0002e639 pthread_cond_wait + 33
2   CoreMedia                           0x00002f1b WaitOnCondition + 11
3   CoreMedia                           0x00002e61 FigSemaphoreWaitRelative + 73
4   MediaToolbox                        0x00003e4b fpa_AsyncMovieControlThread + 55
5   CoreMedia                           0x0001e4c3 figThreadMain + 139
6   libSystem.B.dylib                   0x0007a98d _pthread_start + 249

Thread 8:
0   libSystem.B.dylib                   0x000016cc semaphore_timedwait_signal_trap + 8
1   libSystem.B.dylib                   0x0002ea07 _pthread_cond_wait + 679
2   libSystem.B.dylib                   0x0002f5b9 pthread_cond_timedwait_relative_np + 17
3   CoreMedia                           0x00002e7f FigSemaphoreWaitRelative + 103
4   MediaToolbox                        0x000bfb53 FigMediaValidatorValidateAsyncInternal + 399
5   MediaToolbox                        0x00038a0d FigMediaValidatorCreate + 53
6   Celestial                           0x00015093 -[AVFileValidator validateBlocking:] + 303
7   Celestial                           0x0000beb1 -[AVFileValidator validate] + 17
8   MediaPlayer                         0x0006ead3 -[MPMovie _determineMediaType] + 335
9   Foundation                          0x00086c8d __NSFireDelayedPerform + 369
10  CoreFoundation                      0x00071a5b __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 15
11  CoreFoundation                      0x00073ee5 __CFRunLoopDoTimer + 861
12  CoreFoundation                      0x00074865 __CFRunLoopRun + 1089
13  CoreFoundation                      0x0001d8eb CFRunLoopRunSpecific + 231
14  CoreFoundation                      0x0001d7f3 CFRunLoopRunInMode + 59
15  Foundation                          0x00004d67 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 203
16  Foundation                          0x000863bf -[NSRunLoop(NSRunLoop) runUntilDate:] + 63
17  MediaPlayer                         0x0000e927 -[MPMoviePlayerControllerNew thumbnailImageAtTime:timeOption:] + 119
18  CoreFoundation                      0x0009f074 __invoking___ + 68
19  CoreFoundation                      0x0003270d -[NSInvocation invoke] + 109
20  MediaPlayer                         0x0000bd7f -[MPMoviePlayerController forwardInvocation:] + 47
21  CoreFoundation                      0x0009ef59 ___forwarding___ + 577
22  CoreFoundation                      0x00031680 _CF_forwarding_prep_0 + 48
23  App                                 0x0004f94f 0x1000 + 321871
24  Foundation                          0x0000dd1b -[__NSOperationInternal start] + 659
25  Foundation                          0x0000da7f -[NSOperation start] + 23
26  Foundation                          0x0007e5bb ____startOperations_block_invoke_2 + 47
27  libSystem.B.dylib                   0x000d5c5c _dispatch_call_block_and_release + 20
28  libSystem.B.dylib                   0x000d6a3c _dispatch_worker_thread2 + 128
29  libSystem.B.dylib                   0x0007ad89 _pthread_wqthread + 265

Thread 9:
0   libSystem.B.dylib                   0x0007b85c __workq_kernreturn + 8

Thread 0 crashed with ARM (Native) Thread State:
    r0: 0x00000000     r1:  0x064386ec     r2:  0x06436fa0     r3:  0x00000004 
    r4: 0x30c178e0     r5:  0x00000000     r6:  0x332d1074     r7:  0x2fffeb20 
    r8: 0x06434e40     r9:  0x2fffeafc    r10:  0x00000000    r11:  0x3e1e1ae0 
   r12: 0x3e1da394     sp:  0x2fffeb1c     lr:  0x30ba0c35     pc:  0x307a86b0 

------ 编辑

在另一次执行中，出现了一个不同的堆栈:

Thread 0 Crashed:
0   libobjc.A.dylib                     0x0000286c objc_msgSend + 16
1   Celestial                           0x0001b025 -[AVPlaybackItem release] + 73
2   Celestial                           0x00005d71 -[AVPlaybackQueue queueItemWasAddedNotification:] + 473
3   Foundation                          0x00018fb7 _nsnote_callback + 143
4   CoreFoundation                      0x00069e73 __CFXNotificationPost_old + 403
5   CoreFoundation                      0x0001a37b _CFXNotificationPostNotification + 119
6   Foundation                          0x000040c3 -[NSNotificationCenter postNotificationName:object:userInfo:] + 71
7   Celestial                           0x00005b67 -[AVQueue itemWasAdded:atIndex:] + 127
8   Celestial                           0x00005a01 -[AVQueue insertItem:atIndex:error:] + 157
9   Celestial                           0x0000594f -[AVQueue appendItem:error:] + 47
10  Celestial                           0x000051bb -[AVController addNextFeederItemToQueue] + 199
11  Celestial                           0x000050d7 -[AVController checkQueueSpace] + 111
12  Celestial                           0x000024d1 -[AVController setQueue:] + 101
13  Celestial                           0x00004cb1 -[AVController setQueueFeeder:withIndex:] + 301
14  MediaPlayer                         0x0001f999 -[MPAVController _setAVControllerQueueFeeder:startQueueIndex:] + 97
15  MediaPlayer                         0x0001e53d -[MPAVController reloadFeederWithStartQueueIndex:] + 121
16  MediaPlayer                         0x0000c511 -[MPMoviePlayerControllerNew _prepareToPlayWithStartIndex:] + 325
17  MediaPlayer                         0x0000acad -[MPMoviePlayerControllerNew prepareToPlay] + 29
18  MediaPlayer                         0x00009617 -[MPMoviePlayerControllerNew _movieSourceTypeAvailableNotification:] + 191
19  Foundation                          0x00018fb7 _nsnote_callback + 143
20  CoreFoundation                      0x00069e73 __CFXNotificationPost_old + 403
21  CoreFoundation                      0x0001a37b _CFXNotificationPostNotification + 119
22  Foundation                          0x000040c3 -[NSNotificationCenter postNotificationName:object:userInfo:] + 71
23  Foundation                          0x0000c459 -[NSNotificationCenter postNotificationName:object:] + 25
24  MediaPlayer                         0x0006e0a5 -[MPMovie _fileValidationDidFinishNotification:] + 193
25  Foundation                          0x00018fb7 _nsnote_callback + 143
26  CoreFoundation                      0x00069e73 __CFXNotificationPost_old + 403
27  CoreFoundation                      0x0001a37b _CFXNotificationPostNotification + 119
28  Foundation                          0x0000ba8f -[NSNotificationCenter postNotification:] + 139
29  Celestial                           0x00014719 -[AVFileValidator postNotificationForCallback:] + 65
30  CoreFoundation                      0x000277ff -[NSObject(NSObject) performSelector:withObject:] + 23
31  Celestial                           0x000094a5 -[AVObjectRegistry safeInvokeWithDescription:] + 125
32  CoreFoundation                      0x000277ff -[NSObject(NSObject) performSelector:withObject:] + 23
33  Foundation                          0x00090bbd __NSThreadPerformPerform + 269
34  CoreFoundation                      0x00071a8d __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 13
35  CoreFoundation                      0x0007376f __CFRunLoopDoSources0 + 383
36  CoreFoundation                      0x0007450b __CFRunLoopRun + 231
37  CoreFoundation                      0x0001d8eb CFRunLoopRunSpecific + 231
38  CoreFoundation                      0x0001d7f3 CFRunLoopRunInMode + 59
39  GraphicsServices                    0x000036ef GSEventRunModal + 115
40  GraphicsServices                    0x0000379b GSEventRun + 63
41  UIKit                               0x000062a7 -[UIApplication _run] + 403
42  UIKit                               0x00004e17 UIApplicationMain + 671
43  App                                 0x000031c3 0x1000 + 8643

Answer 1

实际上，这种生成视频缩略图的代码应该在主线程上执行。

这与 iOS 4.0.1 无关。

即使在 NSOperation 下，您也可以通过 performSelectorOnMainThread 执行缩略图生成，应该没问题。