AVfoundation在视频中模糊背景

问题描述

在我的应用程序中，我修复了合成渲染大小为1280 x 720.因此，如果要导入任何肖像视频，那么我必须在中心显示带有填充和视频宽高比的模糊背景。同样如下：

In my application I have fix composition render size of 1280 x 720. So if will import any portrait video then I have to show blur background with fill and aspect frame of video in centre. Same like this:

我使用 AVMtableComposition ，但我不知道如何模糊特定的背景音轨。我在我的代码中做了以下操作：

I achieved to play both videos using AVMtableComposition, but I don't know how to blur a particular background track. I did following in my code:

self.composition = [AVMutableComposition composition];
AVAsset *firstAsset = [AVAsset assetWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"ScreenFlow_Blend" ofType:@"mp4"]]];


[self addAsset:firstAsset toComposition:self.composition withTrackID:1];
[self addAsset:firstAsset toComposition:self.composition withTrackID:2];
//  [self addAsset:ThirdAsset toComposition:self.composition withTrackID:3];

AVAssetTrack *backVideoTrack = [firstAsset tracksWithMediaType:AVMediaTypeVideo][0];;

self.videoComposition = [AVMutableVideoComposition videoComposition];
self.videoComposition.renderSize = CGSizeMake(1280, 720);
self.videoComposition.frameDuration = CMTimeMake(1, 30);

AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = [backVideoTrack timeRange];

CGFloat scale = 1280/backVideoTrack.naturalSize.width;
CGAffineTransform t = CGAffineTransformMakeScale(scale, scale);
t = CGAffineTransformTranslate(t, 0, -backVideoTrack.naturalSize.height/2 + self.videoComposition.renderSize.height/2);

AVMutableVideoCompositionLayerInstruction *frontLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstruction];
frontLayerInstruction.trackID = 1;
[frontLayerInstruction setTransform:t atTime:kCMTimeZero];

CGFloat scaleSmall = 720/backVideoTrack.naturalSize.height;

CGAffineTransform  translate = CGAffineTransformMakeTranslation(self.videoComposition.renderSize.width/2 - ((backVideoTrack.naturalSize.width/2)*scaleSmall),0);

CGAffineTransform  scaleTransform = CGAffineTransformMakeScale(scaleSmall,scaleSmall);

CGAffineTransform finalTransform = CGAffineTransformConcat(scaleTransform, translate);


CGAffineTransform t1 = CGAffineTransformMakeScale(scaleSmall,scaleSmall);
t1 = CGAffineTransformTranslate(t1,1280, 0);

AVMutableVideoCompositionLayerInstruction *backLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstruction];
backLayerInstruction.trackID = 2;
[backLayerInstruction setTransform:finalTransform atTime:kCMTimeZero];


//    AVMutableVideoCompositionLayerInstruction *maskLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstruction];
//    maskLayerInstruction.trackID = 3;
//    [maskLayerInstruction setTransform:t atTime:kCMTimeZero];


instruction.layerInstructions = @[backLayerInstruction,frontLayerInstruction];

self.videoComposition.instructions = @[ instruction ];

AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:self.composition];
playerItem.videoComposition = self.videoComposition;
self.player = [AVPlayer playerWithPlayerItem:playerItem];

AVPlayerLayer *newPlayerLayer = [AVPlayerLayer playerLayerWithPlayer:[self player]];
[newPlayerLayer setFrame:[[[self playerView] layer] bounds]];
// [newPlayerLayer setHidden:YES];

[[[self playerView] layer] addSublayer:newPlayerLayer];
[self setPlayerLayer:newPlayerLayer];

使用上面的代码我可以做到这一点：

Using above code I can achieve this:

我知道用于过滤合成帧的 customVideoCompositor 类。我尝试了但是如果我使用 customVideoCompositor 那么我就失去了对合成层的转换。另外，来自 customVideoCompositor 我不知道如何过滤特定的曲目ID。

I know about the customVideoCompositor class to filter composition frames. I tried it but if I use customVideoCompositor then I am loosing my transformation on composition layers. Plus, from customVideoCompositor I don't know how to filter a particular track id.

如果有人有任何文档链接或建议然后非常感谢你前进。

If someone have any docs link or suggestion then it's really appreciate go forward in this.

推荐答案

在添加第二个视频层之前，它位于屏幕，添加此代码

Before adding the second video layer which is on the centre of the screen, add this code

UIVisualEffect *blurEffect;
blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleExtraLight];//Change the effect which you want.

UIVisualEffectView *visualEffectView;
visualEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];

visualEffectView.frame = self.view.bounds;
[self.view addSubview:visualEffectView];

在Swift中

    let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.Light) //Change the style which suites you
    let blurEffectView = UIVisualEffectView(effect: blurEffect)
    blurEffectView.frame = view.bounds
    blurEffectView.autoresizingMask = [.FlexibleWidth, .FlexibleHeight] // for supporting device rotation
    view.addSubview(blurEffectView)

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