视频轨道后面的AVFoundation UIImage [英] AVFoundation UIImage behind video track

问题描述

我当前正在渲染一个视频轨道，该轨道小于输出大小，可以正常工作.我想将UIImage绘制到背景中，以便视频位于顶部，而图像显示在没有视频的区域中.我已经尝试过将CoreAnimation图层与videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:inLayer一起使用: 但是视频层以下的层似乎无法显示(上面的层显示得很好)-只是黑色或我在AVMutableVideoCompositionInstruction对象上设置的任何背景色.我也尝试将背景色设置为[UIColor clearColor] .CGColor，但它只是通过黑色而来.

I'm currently rendering a video track that is smaller than the output size which is working fine. I want to draw a UIImage into the background so that the video is on top with the image showing in the area where the video isn't. I've tried using CoreAnimation Layers along with videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:inLayer: but layers below the video layer don't seem to show through (ones above show just fine) - just black or whatever background color I set on the AVMutableVideoCompositionInstruction object. I've also tried setting that background color to [UIColor clearColor].CGColor but it just comes through as black.

有人做过类似的事情并有建议吗?

Anyone done something similar and have suggestions?

CALayer *parentLayer = [CALayer layer];
CALayer *videoLayer = [CALayer layer];
CALayer *backgroundLayer = [CALayer layer];
backgroundLayer.frame = rect;
parentLayer.frame = rect;
videoLayer.frame = rect;
videoLayer.backgroundColor = [UIColor clearColor].CGColor;
backgroundLayer.backgroundColor = [UIColor purpleColor].CGColor;
[parentLayer addSublayer:backgroundLayer];
[parentLayer addSublayer:videoLayer];

mainCompositionInst.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

推荐答案

在尝试了几件事之后，我终于找到了解决之道.要使其正常工作，需要使用空白的视频/音频轨道.然后将背景图像叠加层添加到该空白视频层.然后将其导出，并结合原始资产(视频)和导出资产(资产)并导出最终资产(视频).希望对您有所帮助.

After trying several things finally I got a way to work it. To make it work need to use a blank video/audio track. Then add background image an overlay to this blank video layer. Then export it and combine the original asset(video) and exported asset(asset) and export the final asset(video).Hope it will help you.

添加叠加层

- (void)addOverlayImage:(UIImage *)overlayImage ToVideo:(AVMutableVideoComposition *)composition inSize:(CGSize)size {
    // 1 - set up the overlay
    CALayer *overlayLayer = [CALayer layer];

    [overlayLayer setContents:(id)[overlayImage CGImage]];
    overlayLayer.frame = CGRectMake(0, 0, size.width, size.height);
    [overlayLayer setMasksToBounds:YES];

    // 2 - set up the parent layer
    CALayer *parentLayer = [CALayer layer];
    CALayer *videoLayer = [CALayer layer];
    parentLayer.frame = CGRectMake(0, 0, size.width, size.height);
    videoLayer.frame = CGRectMake(0, 0, size.width, size.height);
    [parentLayer addSublayer:videoLayer];
    [parentLayer addSublayer:overlayLayer];

    // 3 - apply magic
    composition.animationTool = [AVVideoCompositionCoreAnimationTool
                                 videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];
}

- (void)getBackgroundVideoAssetWithcompletion:(void (^)(AVAsset *bgAsset))completionBlock {

    NSString *path = [[NSBundle mainBundle] pathForResource:@"blank_video" ofType:@"mp4"];
    NSURL *trackUrl = [NSURL fileURLWithPath:path];
    AVAsset *asset = [AVAsset assetWithURL:trackUrl];
    AVAssetTrack *track = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

    CMTimeRange range = CMTimeRangeMake(kCMTimeZero, [asset duration]);
    AVMutableComposition* mixComposition = [AVMutableComposition composition];

    AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    [compositionVideoTrack insertTimeRange:range ofTrack:[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:kCMTimeZero error:nil];


    CGAffineTransform videoTransform = track.preferredTransform;
    CGSize naturalSize = CGSizeApplyAffineTransform(track.naturalSize, videoTransform);
    naturalSize = CGSizeMake(fabs(naturalSize.width), fabs(naturalSize.height));


    AVMutableVideoComposition *composition = [AVMutableVideoComposition videoCompositionWithPropertiesOfAsset:asset];
    UIImage *img = [self imageWithImage:[UIImage imageNamed:@"white_image"] convertToSize:naturalSize];
    [self addOverlayImage:img ToVideo:composition inSize:naturalSize];


    AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    instruction.timeRange = range;
    composition.instructions = @[instruction];


    AVAssetExportSession *_assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetMediumQuality];
    _assetExport.videoComposition = composition;



    NSString *exportPath = [NSTemporaryDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"exported-%d.mov", arc4random() % 100000]];
    unlink([exportPath UTF8String]);
    NSURL *exportUrl = [NSURL fileURLWithPath:exportPath];

    _assetExport.outputFileType = AVFileTypeQuickTimeMovie;
    _assetExport.outputURL = exportUrl;
    _assetExport.shouldOptimizeForNetworkUse = YES;

    [_assetExport exportAsynchronouslyWithCompletionHandler:^{

        switch (_assetExport.status) {

            case AVAssetExportSessionStatusFailed:
                 break;

            case AVAssetExportSessionStatusExporting:
                break;

            case AVAssetExportSessionStatusCompleted:{

                dispatch_async(dispatch_get_main_queue(), ^{
                    NSLog(@"Successful!!!");
                    AVAsset *finalAsset = [AVAsset assetWithURL:_assetExport.outputURL];
                    completionBlock(finalAsset);
                });
            }
                break;

            default:
                break;
        }
    }];
}

现在有一个带有重叠图像的视频资产.剩下的就是将原始视频和导出的视频资产结合起来了.出口资产应位于最底层，原始资产应位于最顶层.

Now there is a video asset with an overlay image. Only thing is remain to combine original video and the exported video asset. Exported asset should be bottom layer and original should be top layer.

这篇关于视频轨道后面的AVFoundation UIImage的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！