AvMutableComposition問題在最後有黑框

我在iOS應用中使用AVCaptureConnection捕獲視頻。之後，我在視頻中添加一些圖片作爲CALayers。一切工作正常，但在添加圖像後，我在結果視頻的最後得到了一個黑框。沒有實際的音頻/視頻幀受到影響。對於音頻，我提取它並更改它的音高，然後使用AVMutableComposition添加它。這是我正在使用的代碼。請幫我解決我所做的錯誤，或者我需要添加其他內容。AvMutableComposition問題在最後有黑框

cmp = [AVMutableComposition composition]; 

    AVMutableCompositionTrack *videoComposition = [cmp addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; 
    AVMutableCompositionTrack *audioComposition = [cmp addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; 
    AVAssetTrack *sourceVideoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]; 
    AVAssetTrack *sourceAudioTrack = [[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]; 


    [videoComposition insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:sourceVideoTrack atTime:kCMTimeZero error:nil] ; 
    [audioComposition insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:sourceAudioTrack atTime:kCMTimeZero error:nil]; 

    animComp = [AVMutableVideoComposition videoComposition]; 
    animComp.renderSize = CGSizeMake(320, 320); 
    animComp.frameDuration = CMTimeMake(1,30); 
    animComp.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer]; 

    // to gather the audio part of the video 
    NSArray *tracksToDuck = [cmp tracksWithMediaType:AVMediaTypeAudio]; 
    NSMutableArray *trackMixArray = [NSMutableArray array]; 
    for (NSInteger i = 0; i < [tracksToDuck count]; i++) { 
     AVMutableAudioMixInputParameters *trackMix = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:[tracksToDuck objectAtIndex:i]]; 
     [trackMix setVolume:5 atTime:kCMTimeZero]; 
     [trackMixArray addObject:trackMix]; 
    } 
    audioMix = [AVMutableAudioMix audioMix]; 
    audioMix.inputParameters = trackMixArray; 

    AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction]; 
    instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [asset duration]); 
    AVMutableVideoCompositionLayerInstruction *layerVideoInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoComposition]; 

    [layerVideoInstruction setOpacity:1.0 atTime:kCMTimeZero]; 
    instruction.layerInstructions = [NSArray arrayWithObject:layerVideoInstruction] ; 
    animComp.instructions = [NSArray arrayWithObject:instruction]; 
    [self exportMovie:self];

這是我導出視頻

-(IBAction) exportMovie:(id)sender{ 

    //successCheck = NO; 
    NSArray *docPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *tempPath = [docPaths objectAtIndex:0]; 
    //NSLog(@"Temp Path: %@",tempPath); 

    NSString *fileName = [NSString stringWithFormat:@"%@/Final.MP4",tempPath]; 
    NSFileManager *fileManager = [NSFileManager defaultManager] ; 
    if([fileManager fileExistsAtPath:fileName ]){ 
     NSError *ferror = nil ; 
     [fileManager removeItemAtPath:fileName error:&ferror]; 
    } 

    NSURL *exportURL = [NSURL fileURLWithPath:fileName]; 

    AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:cmp presetName:AVAssetExportPresetMediumQuality] ; 
    exporter.outputURL = exportURL; 
    exporter.videoComposition = animComp; 
    //exporter.audioMix = audioMix; 
    exporter.outputFileType = AVFileTypeQuickTimeMovie; 

    [exporter exportAsynchronouslyWithCompletionHandler:^(void){ 
     switch (exporter.status) { 
      case AVAssetExportSessionStatusFailed:{ 
       NSLog(@"Fail"); 
       break; 
      } 
      case AVAssetExportSessionStatusCompleted:{ 
       NSLog(@"Success video"); 
           }); 
       break; 
      } 

      default: 
       break; 
     } 
      }]; 
    NSLog(@"outside"); 
}

來源

2013-04-05 Swati

你在哪個部分改變了音調？我正在尋找改變導出音頻的音調，但遇到一些麻煩... – simplexity 2017-03-04 02:14:45

方法有給的時間範圍內，試着給時間範圍略小於實際的時間（幾納秒少exportsession的屬性）

來源

2013-04-09 05:03:09 Khushboo

感謝khushboo。我有同樣的問題。作爲我的考驗。只有10.7系統版本有這個問題。 10.8沒有。通過設置導出會話的時間範圍解決了這個問題。

來源

2013-08-20 10:05:06 dinosaur

AvMutableComposition問題在最後有黑框

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