裁剪视频文件中的方向问题

Question

嗨，我只是简单地裁剪视频文件并通过 AVAssetExportSession 将其导出到目录中。 但问题是纵向视频将方向更改为横向并在我保存的目录中显示为旋转 90 度。我不明白它将如何修复。我的代码有什么问题吗。希望你能理解。

firstAsset = [AVAsset assetWithURL:firstUrl];

if(firstAsset !=nil)
{

 AVVideoComposition *origionalComposition = [AVVideoComposition videoCompositionWithPropertiesOfAsset:firstAsset];
    AVMutableComposition* mixComposition = [[AVMutableComposition alloc] init];

    //VIDEO TRACK

    AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    [firstTrack insertTimeRange:timeRange ofTrack:[[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:kCMTimeZero error:nil];

AVMutableVideoCompositionInstruction * MainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction]; MainInstruction.timeRange = timeRange;

    AVMutableVideoCompositionLayerInstruction *FirstlayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:firstTrack];
    AVAssetTrack *FirstAssetTrack = [[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];


    [FirstlayerInstruction setTransform:FirstAssetTrack.preferredTransform atTime:kCMTimeZero];

    MainInstruction.layerInstructions = [NSArray arrayWithObjects:FirstlayerInstruction,nil];

    AVMutableVideoComposition *MainCompositionInst = [AVMutableVideoComposition videoComposition];
    MainCompositionInst.instructions = [NSArray arrayWithObject:MainInstruction];
    MainCompositionInst.frameDuration = origionalComposition.frameDuration;
     MainCompositionInst.renderScale = 1.0;
    MainCompositionInst.renderSize = CGSizeMake(FirstAssetTrack.naturalSize.height, FirstAssetTrack.naturalSize.width);

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"Crop Videos"];

    NSString *videoName =[NSString stringWithFormat:@"Video_%d.mov",videoNumber];
    NSString *myPathDocs =  [documentsDirectory stringByAppendingPathComponent:videoName];


    NSURL *url = [NSURL fileURLWithPath:myPathDocs];

    AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetMediumQuality];
    exporter.outputURL=url;
    exporter.outputFileType = AVFileTypeQuickTimeMovie;
    exporter.shouldOptimizeForNetworkUse = YES;
    [exporter exportAsynchronouslyWithCompletionHandler:^
     {
         dispatch_async(dispatch_get_main_queue(), ^{
             [self exportDidFinish:exporter];
         });
     }];
}

如果有人知道请回答..提前谢谢

Answer 1

您还没有添加 AVMutableVideoCompositionLayerInstruction，请确保您进行了相应更改

// 1.0 - Create an AVMutableVideoCompositionLayerInstruction for the video track and fix the  orientation.

AVMutableVideoCompositionLayerInstruction *videolayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
AVAssetTrack *videoAssetTrack = [[self.videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

BOOL isVideoAssetPortrait_  = NO;
CGAffineTransform videoTransform = videoAssetTrack.preferredTransform;
if (videoTransform.a == 0 && videoTransform.b == 1.0 && videoTransform.c == -1.0 && videoTransform.d == 0) {
    isVideoAssetPortrait_ = YES;
}
if (videoTransform.a == 0 && videoTransform.b == -1.0 && videoTransform.c == 1.0 && videoTransform.d == 0) {

    isVideoAssetPortrait_ = YES;
}
if (videoTransform.a == 1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == 1.0) {
    isVideoAssetPortrait_  = NO;
}
if (videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0) {
    isVideoAssetPortrait_  = NO;
}
[videolayerInstruction setTransform:videoAssetTrack.preferredTransform atTime:kCMTimeZero];
[videolayerInstruction setOpacity:0.0 atTime:self.videoAsset.duration];

// 1.2 - Add instructions
mainInstruction.layerInstructions = [NSArray arrayWithObjects:videolayerInstruction,nil];

AVMutableVideoComposition *mainCompositionInst = [AVMutableVideoComposition videoComposition];

CGSize naturalSize;
if(isVideoAssetPortrait_){
    naturalSize = CGSizeMake(videoAssetTrack.naturalSize.height, videoAssetTrack.naturalSize.width);
} else {
    naturalSize = videoAssetTrack.naturalSize;
}

mainCompositionInst.renderSize = naturalSize;
mainCompositionInst.instructions = [NSArray arrayWithObject:mainInstruction];
mainCompositionInst.frameDuration = CMTimeMake(1, 30);

Answer 2

这是运行代码：

AVURLAsset* videoAsset = [AVURLAsset assetWithURL:"PATH OF VIDEO"]; 
//create mutable composition
AVMutableComposition *mixComposition = [AVMutableComposition composition];

AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
                                                                               preferredTrackID:kCMPersistentTrackID_Invalid];

[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
                                                        ofTrack:[[videoAsset  tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
                                                         atTime:kCMTimeZero
                                                          error:&videoInsertError];



AVMutableVideoCompositionInstruction * MainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];

MainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, videoAsset.duration);

//FIXING ORIENTATION//
AVMutableVideoCompositionLayerInstruction *FirstlayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTrack];

AVAssetTrack *FirstAssetTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

UIImageOrientation FirstAssetOrientation_  = UIImageOrientationUp;

BOOL  isFirstAssetPortrait_  = NO;

CGAffineTransform firstTransform = FirstAssetTrack.preferredTransform;

if(firstTransform.a == 0 && firstTransform.b == 1.0 && firstTransform.c == -1.0 && firstTransform.d == 0)
{
    FirstAssetOrientation_= UIImageOrientationRight;
    isFirstAssetPortrait_ = YES;
}
if(firstTransform.a == 0 && firstTransform.b == -1.0 && firstTransform.c == 1.0 && firstTransform.d == 0)
{
    FirstAssetOrientation_ =  UIImageOrientationLeft;
    isFirstAssetPortrait_ = YES;
}
if(firstTransform.a == 1.0 && firstTransform.b == 0 && firstTransform.c == 0 && firstTransform.d == 1.0)
{
    FirstAssetOrientation_ =  UIImageOrientationUp;
}
if(firstTransform.a == -1.0 && firstTransform.b == 0 && firstTransform.c == 0 && firstTransform.d == -1.0)
{
    FirstAssetOrientation_ = UIImageOrientationDown;
}

CGFloat FirstAssetScaleToFitRatio = 1.0;

if(isFirstAssetPortrait_)
{
    FirstAssetScaleToFitRatio = FirstAssetTrack.naturalSize.width/FirstAssetTrack.naturalSize.height;
    CGAffineTransform FirstAssetScaleFactor = CGAffineTransformMakeScale(FirstAssetScaleToFitRatio,FirstAssetScaleToFitRatio);
    [FirstlayerInstruction setTransform:CGAffineTransformConcat(FirstAssetTrack.preferredTransform, FirstAssetScaleFactor) atTime:kCMTimeZero];
}
else
{
    CGAffineTransform FirstAssetScaleFactor = CGAffineTransformMakeScale(FirstAssetScaleToFitRatio,FirstAssetScaleToFitRatio);
    [FirstlayerInstruction setTransform:CGAffineTransformConcat(CGAffineTransformConcat(FirstAssetTrack.preferredTransform, FirstAssetScaleFactor),CGAffineTransformMakeTranslation(0, 0)) atTime:kCMTimeZero];
}
[FirstlayerInstruction setOpacity:0.0 atTime:videoAsset.duration];

MainInstruction.layerInstructions = [NSArray arrayWithObjects:FirstlayerInstruction,nil];

AVMutableVideoComposition *MainCompositionInst = [AVMutableVideoComposition videoComposition];
MainCompositionInst.instructions = [NSArray arrayWithObject:MainInstruction];
MainCompositionInst.frameDuration = CMTimeMake(1, 30);
//MainCompositionInst.renderSize = CGSizeMake(FirstAssetTrack.naturalSize.width, FirstAssetTrack.naturalSize.height);
MainCompositionInst.renderSize = [[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize];

最后是save 或使用AVAssetExportSession 类“导出”

export.outputURL=FinalPath;