ios - 在 iOS 中以编程方式将录制的视频旋转 90 度

Question

我在 iPhone 中录制了一段视频，并且正在获取其本地文件 URL。有什么方法可以使用 URL 将该视频旋转 90 度吗？

Answer 1

您可以在导出 session 之前使用 AVMutableVideoCompositionLayerInstruction 类旋转视频，并且可以对其应用 Transform。

这就是方法

 [yourlayerInstruction setTransform:CGAffineTransformMakeRotation(M_PI/2) atTime:firstAssets.duration];

这是完整的实现

          AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];

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


          AVMutableVideoCompositionInstruction * mainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
            mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeAdd(firstAsset.duration, secondAsset.duration));

          AVMutableVideoCompositionLayerInstruction *firstlayerInstruction = [AVMutableVideoCompositionLayerInstruction 
    videoCompositionLayerInstructionWithAssetTrack:firstTrack]; 

// set Trasform Here 
  [firstlayerInstruction setTransform:CGAffineTransformMakeRotation(M_PI/2) atTime:kCMTimeZero];

       [firstlayerInstruction setOpacity:0.0 atTime:firstAsset.duration];

          mainInstruction.layerInstructions = [NSArray arrayWithObjects:firstlayerInstruction,nil];;

         AVMutableVideoComposition *mainCompositionInst = [AVMutableVideoComposition videoComposition];

         mainCompositionInst.instructions = [NSArray arrayWithObject:mainInstruction];
            mainCompositionInst.frameDuration = CMTimeMake(1, 30);
            mainCompositionInst.renderSize = CGSizeMake(320.0, 480.0);

         AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition
                                                                              presetName:AVAssetExportPreset640x480];
            exporter.outputURL=url;
            exporter.videoComposition=mainCompositionInst;
            exporter.outputFileType = AVFileTypeQuickTimeMovie;
            exporter.shouldOptimizeForNetworkUse = YES;
            [exporter exportAsynchronouslyWithCompletionHandler:^{
                dispatch_async(dispatch_get_main_queue(), ^
                {
                    [self exportDidFinish:exporter];
                });
            }];

希望这对你有帮助