AVExportSession工作在模擬器，iPad 2的而不是iPad的4

Question

更新：奇怪的是這個代碼工作正常在iPad 2，但沒有一個iPad 4日創

更新＃2：如果我改變presetName:AVAssetExportPresetHighestQuality到presetName:AVAssetExportPresetPassThrough視頻成功出口但我無法在設備中播放它。如果我通過xCode的組織者將應用程序包關閉到我的電腦，我可以播放它。再次，這個問題只發生在iPad 4上，而不是iPad 2，64位模擬器，視網膜模擬器或1x模擬器。

我正在使用AVExportSession混合一些音頻和視頻。它在模擬器和iPad 2上運行相當愉快，但不是iPad第4代。導出會話出現-11820錯誤（AVErrorExportFailed），但這是我能夠從流程中獲得的有用信息的範圍。源文件存在，其他所有內容都在流暢地運行，但不是AVExportSession。

你能幫助我在設備上工作嗎？

道歉的方法的詳細程度。

-(NSURL*)bindAudioAndVideo:(NSString*)audioFileName videoFileName:(NSString*)videoFileName 
{ 

    //documents folder 
    NSArray  *paths    = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsFolder  = [[NSString alloc] initWithString:[paths objectAtIndex:0]]; //Get the docs directory 

    AVMutableComposition* mixComposition = [AVMutableComposition composition]; 

    NSString* audio_inputFileName = audioFileName; 
    NSString* audio_inputFilePath = [documentsFolder stringByAppendingPathComponent:audio_inputFileName]; 
    NSURL* audio_inputFileUrl = [NSURL fileURLWithPath:audio_inputFilePath]; 

    NSString* video_inputFileName = videoFileName; 
    NSString* video_inputFilePath = [documentsFolder stringByAppendingPathComponent:video_inputFileName]; 
    NSURL* video_inputFileUrl = [NSURL fileURLWithPath:video_inputFilePath]; 

    NSString* outputFileName  = @"outputFile.mp4"; 
    NSString* outputFilePath  = [documentsFolder stringByAppendingPathComponent:outputFileName]; 
    NSURL* outputFileUrl   = [NSURL fileURLWithPath:outputFilePath]; 

    //Check files actually exist before beginning (they do) 

    AVMutableComposition* mixComposition = [AVMutableComposition composition]; 
    CMTime nextClipStartTime = kCMTimeZero; 

    AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:video_inputFileUrl options:nil]; 
    CMTimeRange video_timeRange = CMTimeRangeMake(kCMTimeZero,videoAsset.duration); 
    AVMutableCompositionTrack *a_compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; 
    [a_compositionVideoTrack insertTimeRange:video_timeRange ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:nextClipStartTime error:nil]; 


    AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:audio_inputFileUrl options:nil]; 
    CMTimeRange audio_timeRange = CMTimeRangeMake(kCMTimeZero, audioAsset.duration); 
    AVMutableCompositionTrack *b_compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; 
    [b_compositionAudioTrack insertTimeRange:audio_timeRange ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:nextClipStartTime error:nil]; 



    AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality]; 
    _assetExport.outputFileType = @"com.apple.quicktime-movie"; 
    _assetExport.outputURL = outputFileUrl; 

    [_assetExport exportAsynchronouslyWithCompletionHandler: 
    ^(void) { 
     [self addSkipBackupAttributeToItemAtURL:outputFileUrl]; 
     NSLog(@"Completed. Tidy time."); 

     switch ([_assetExport status]) { 
      case AVAssetExportSessionStatusCompleted: 
       NSLog(@"Export Completed"); 
       break; 
      case AVAssetExportSessionStatusFailed: 
       NSLog(@"Export failed: %@", [[_assetExport error] localizedDescription]); 
       NSLog (@"FAIL %@",_assetExport.error); //-11820! I AM A USELESS ERROR CODE 
       NSLog (@"supportedFileTypes: %@", _assetExport.supportedFileTypes); 
       break; 
      case AVAssetExportSessionStatusCancelled: 
       NSLog(@"Export cancelled"); 
       break; 
      default: 
       break; 
     } 


      NSTimer *refreshTimer = [NSTimer timerWithTimeInterval:0.1 target:self selector:@selector(exportCompleteRefreshView) userInfo:Nil repeats:NO]; 

     //Throw back to main thread unuless you want really long delays for no reason. 
     [[NSRunLoop mainRunLoop] addTimer:refreshTimer forMode:NSRunLoopCommonModes]; 
    } 
    ]; 



    return outputFileUrl; 
} 

Answer 1

如果問題與視網膜iPad連接 - 這與設備分辨率有關，由於某種原因，模擬器沒有模擬。

由於我是在設備上創建視頻，我在視網膜設備上製作了2048x1536視頻（而在非視網膜設備上是1024x768）。顯然這只是AVExportSession處理的像素太多，或者iPad可以正常播放，所以它只是在播放或導出時向我發送了各種模糊的錯誤信息。在點分辨率而不是像素分辨率下錄製似乎解決了問題。

該模擬器似乎是一個紅色的鯡魚，因爲它擁有一個健康的mac相對無限的資源，而不是A6。