Question

我正致力于视频裁剪。但是当我裁剪并保存它。它已经错误地保存到景观中。但它只在肖像视频的情况下，它与风景视频工作正常。我想上传图片以便您更好地理解，但至少需要10个声望。不幸的是我没有。

但我尝试过使用AVMutableVideoComposition。

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(nRenderWidth, nRenderHeight);

它不起作用。我不知道如何管理。有人知道请回答我，我在等待回应。我正在使用AVAssetExportSession来保存裁剪的视频文件。

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

Answer 1

VAAssetTrak 有preferredTransform，此转换用于将视频旋转到正确的位置。

    AVMutableVideoCompositionLayerInstruction* transformer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:clipVideoTrack];
   CGAffineTransform videoTransform = clipVideoTrack.preferredTransform;
    if (videoTransform.a == 0 && videoTransform.b == 1.0 && videoTransform.c == -1.0 && videoTransform.d == 0) {
        //portrait mode
        t1 = CGAffineTransformMakeTranslation(clipVideoTrack.naturalSize.height-translateX, -translateY);
        t2 = CGAffineTransformRotate(t1, M_PI_2);
        finalTransform = t2;
        [transformer setTransform:finalTransform atTime:kCMTimeZero];
    }
    if (videoTransform.a == 0 && videoTransform.b == -1.0 && videoTransform.c == 1.0 && videoTransform.d == 0) {
        //portrait up side down
        t1 = clipVideoTrack.preferredTransform;
        t2 = CGAffineTransformConcat(t1,CGAffineTransformMakeTranslation(translateX , -translateY));
        finalTransform = t2;
        [transformer setTransform:finalTransform atTime:kCMTimeZero];
    }
    if (videoTransform.a == 1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == 1.0) {
        //landscape right
        t1 = clipVideoTrack.preferredTransform;
        t2 = CGAffineTransformConcat(t1,CGAffineTransformMakeTranslation(-translateX , -translateY));
        finalTransform = t2;
        [transformer setTransform:finalTransform atTime:kCMTimeZero];
    }
    if (videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0) {
        //landscape left
        t1 = clipVideoTrack.preferredTransform;
        t2 = CGAffineTransformConcat(t1,CGAffineTransformMakeTranslation(-translateX , -translateY));
        finalTransform = t2;
        [transformer setTransform:finalTransform atTime:kCMTimeZero];

    }

    //add the transformer layer instructions, then add to video composition
    instruction.layerInstructions = [NSArray arrayWithObjects:transformer,nil];

How to use

特别是＆＃34; // FIXING ORIENTATION //＆＃34;

剪裁视频中的纵向视频方向问题

1 个答案: