Question

我有以下代码来修复视频的Tranform

    - (AVVideoComposition *)squareVideoCompositionFor:(AVAsset *)asset {

    AVAssetTrack *track = [asset tracksWithMediaType:AVMediaTypeVideo].firstObject;

    CGFloat length = MAX(track.naturalSize.width, track.naturalSize.height);

    CGSize size = track.naturalSize;

    CGFloat scale = 0;

    CGAffineTransform transform = track.preferredTransform;

    if (transform.a == 0 && transform.b == 1 && transform.c == -1 && transform.d == 0) {
        scale = -1;
    }
    else if (transform.a == 0 && transform.b == -1 && transform.c == 1 && transform.d == 0) {
        scale = -1;
    }
    else if (transform.a == 1 && transform.b == 0 && transform.c == 0 && transform.d == 1) {
        scale = 1;
    }
    else if (transform.a == -1 && transform.b == 0 && transform.c == 0 && transform.d == -1) {
        scale = -1;
    }

    transform = CGAffineTransformTranslate(transform, scale * -(size.width - length) / 2, scale * -(size.height - length) / 2);




    AVMutableVideoCompositionLayerInstruction *transformer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:track];
    [transformer setTransform:transform atTime:kCMTimeZero];

//    CGAffineTransform finalTransform = t2;
//    [transformer setTransform:finalTransform atTime:kCMTimeZero];

    AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    instruction.timeRange = CMTimeRangeMake(kCMTimeZero, kCMTimePositiveInfinity);
    instruction.layerInstructions = @[transformer];


    AVMutableVideoComposition *composition = [AVMutableVideoComposition videoComposition];
    composition.frameDuration = CMTimeMake(1, 30);
    composition.renderSize =  CGSizeMake(length, length);
    composition.instructions = @[instruction];
    composition.renderScale = 1.0;


    return composition;
    }

并遵循静音音频代码

- (AVMutableComposition *) removeAudioFromVideoFileFor:(AVAsset *)asset  {
    AVMutableComposition *composition_Mix = [AVMutableComposition composition];
    AVMutableCompositionTrack *compositionVideoTrack = [composition_Mix addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];

    BOOL ok = NO;

    AVAssetTrack * sourceVideoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

    CMTimeRange x = CMTimeRangeMake(kCMTimeZero, [asset duration]);
    NSError *error;
    ok = [compositionVideoTrack insertTimeRange:x ofTrack:sourceVideoTrack atTime:kCMTimeZero error:&error];

    return composition_Mix;
}

这里我如何调用函数

    AVAsset *asset = [AVAsset assetWithURL:inputURL];

    AVMutableComposition *composition = [self  removeAudioFromVideoFileFor:asset];

    AVAssetExportSession *session = [AVAssetExportSession exportSessionWithAsset:composition presetName:AVAssetExportPresetHighestQuality];
    session.videoComposition = [self squareVideoCompositionFor:asset];
    session.outputURL = outputURL;
    session.outputFileType = AVFileTypeMPEG4;
    session.shouldOptimizeForNetworkUse = true;
    session.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration);

但如果我同时使用composition和[self squareVideoCompositionFor:asset]

，则会显示错误

错误域= AVFoundationErrorDomain代码= -11841＆＃34;操作已停止＆＃34; UserInfo = {NSLocalizedDescription =操作已停止，NSLocalizedFailureReason =视频无法合成。}

如果我省略一个然后它工作正常意味着一个AVAssetExportSession可以静音来自视频或squareVideo

我是否可以使用AVAssetExportSession的单一导出进度来实现这两种方式？

Answer 1

您的代码看起来不错，但是我已经对您的代码进行了更改以使其正常工作。

inputURL和outputURL的前缀应为file://或https://（因为它是url，在您的情况下，应以file://开头）

如果您的密码无效，那么您将无法获得所需的输出。

//FOR OUTPUT URL
NSString *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
path = [path stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];

//the output video will be written to file final.mp4
NSURL *outputURL = [NSURL fileURLWithPath:path];
outputURL = [outputURL URLByAppendingPathComponent:@"final.mp4"];
NSLog(@"outputURL = %@", outputURL);


//FOR INPUT URL
//This is the path of the bundle resource that is going to be used
NSURL *inputURL = [[NSBundle mainBundle] URLForResource:@"video" withExtension:@"mp4"];
NSLog(@"inputURL = %@", inputURL);

导出构图

//this will export the composition with the specified configuration
[session exportAsynchronouslyWithCompletionHandler:^{
    NSLog(@"Success");
}];

在控制台中看到“成功”日志时，请检查应用程序的文档目录。该视频将被写入outptURL。

注意：使用CMD + SHIFT + G并设置输出网址。您将被重定向到应用程序的文档文件夹（仅适用于模拟器）。对于设备，您需要下载应用程序容器并查看软件包内容。

完整的代码

removeAudioFromVideoFileFor:和squareVideoCompositionFor:方法看起来不错。只需更改以下内容即可。

“视频”是应用程序捆绑包中资源文件的名称。

- (void)viewDidLoad {
[super viewDidLoad];


   NSString *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
   path = [path stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
  NSURL *outputURL = [NSURL fileURLWithPath:path];
outputURL = [outputURL URLByAppendingPathComponent:@"final.mp4"];
  NSLog(@"outputURL = %@", outputURL);


  NSURL *inputURL = [[NSBundle mainBundle] URLForResource:@"video" withExtension:@"mp4"];
  NSLog(@"inputURL = %@", inputURL);

  AVAsset *asset = [AVAsset assetWithURL:inputURL];

  AVMutableComposition *composition = [self removeAudioFromVideoFileFor: asset];

  AVAssetExportSession *session = [AVAssetExportSession exportSessionWithAsset:composition presetName:AVAssetExportPresetHighestQuality];
  session.videoComposition = [self squareVideoCompositionFor:asset];
  session.outputURL = outputURL;
  session.outputFileType = AVFileTypeMPEG4;
  session.shouldOptimizeForNetworkUse = true;
  session.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration);

  [session exportAsynchronouslyWithCompletionHandler:^{
     NSLog(@"Success:");
  }];
}

希望这会有所帮助

静音视频+转换视频使用AVAssetExportSession

1 个答案: