使用AVVideoCompositionCoreAnimationTool在CALayer中混合视频和静态图像

Question

我正在尝试将来自摄像头的视频与静态图像（水印）混合。

我查看了这里的一些问题/答案以及一些示例，包括来自苹果的WWDC AVEditDemo，并最终得出以下代码。 不幸的是，导出的视频不包含带有图像的图层。 有什么想法吗？

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

/// incoming video
NSURL *videoURL = [info valueForKey:UIImagePickerControllerMediaURL];

/// UIImage into CALayer
UIImage *myImage = [UIImage imageNamed:@"m1h.png"];
CALayer *aLayer = [CALayer layer];
aLayer.contents = (id)myImage.CGImage;

AVURLAsset* url = [AVURLAsset URLAssetWithURL:videoURL options:nil];
AVMutableComposition *videoComposition = [AVMutableComposition composition];
NSError *error;
NSFileManager *fileManager = [NSFileManager defaultManager];

AVMutableCompositionTrack *compositionVideoTrack = [videoComposition  addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *clipVideoTrack = [[url tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [url duration])  ofTrack:clipVideoTrack atTime:kCMTimeZero error:&error];

AVMutableVideoComposition* videoComp = [[AVMutableVideoComposition videoComposition] retain];
videoComp.renderSize = CGSizeMake(640, 480);
videoComp.frameDuration = CMTimeMake(1, 30);
videoComp.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithAdditionalLayer:aLayer asTrackID:2];


/// instruction
AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(60, 30) );
AVMutableVideoCompositionLayerInstruction* layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:clipVideoTrack];
instruction.layerInstructions = [NSArray arrayWithObject:layerInstruction];
videoComp.instructions = [NSArray arrayWithObject: instruction];

/// outputs
NSString *filePath = nil;
filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
filePath = [filePath stringByAppendingPathComponent:@"temp.mov"]; 
NSLog(@"exporting to: %@", filePath);
if ([fileManager fileExistsAtPath:filePath]) 
{
        BOOL success = [fileManager removeItemAtPath:filePath error:&error];
        if (!success) NSLog(@"FM error: %@", [error localizedDescription]);
}

/// exporting
AVAssetExportSession *exporter;
exporter = [[AVAssetExportSession alloc] initWithAsset:videoComposition presetName:AVAssetExportPresetHighestQuality] ;
exporter.videoComposition = videoComp;
exporter.outputURL=[NSURL fileURLWithPath:filePath];
exporter.outputFileType=AVFileTypeQuickTimeMovie;

[statusLabel setText:@"processing..."];

[exporter exportAsynchronouslyWithCompletionHandler:^(void){
    switch (exporter.status) {
        case AVAssetExportSessionStatusFailed:
            NSLog(@"exporting failed");
            break;
        case AVAssetExportSessionStatusCompleted:
            NSLog(@"exporting completed");
            UISaveVideoAtPathToSavedPhotosAlbum(filePath, self, @selector(video:didFinishSavingWithError:contextInfo:), NULL);
            break;
        case AVAssetExportSessionStatusCancelled:
            NSLog(@"export cancelled");
            break;
    }
}];

}

这是一个简单的HTML段落，其中包含了一个右花括号“}”。

- izne

Answer 1

在做了一些尝试后，除了上述代码外，我最终得到了这样的结果，同时还将使用的方法更改为videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer：

CALayer *parentLayer = [CALayer layer];
CALayer *videoLayer = [CALayer layer];
parentLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height);
videoLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height);
[parentLayer addSublayer:videoLayer];
[parentLayer addSublayer:aLayer];
videoComp.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

希望能对某些人有所帮助。

- izne

---

我遇到了一个类似的问题（请参见这里），但是出现了一些错误。你认为你能帮我吗？ - Mihai Fratu

Answer 2

我已经让它正常工作了！这里是代码！我并没有写太多的代码，只是稍微调整了一些。但唯一的问题是视频在纵向模式下会旋转成横向模式？然后在横向模式下，视频是纵向的，但图像是正确的！

CALayer *aLayer = [CALayer layer];
    aLayer.frame = CGRectMake(5, 0, 320, 480);
    aLayer.bounds = CGRectMake(5, 0, 320, 480);
    aLayer.contents = (id) [UIImage imageNamed:@"image.png"].CGImage;
    aLayer.opacity = 0.5;
    aLayer.backgroundColor = [UIColor clearColor].CGColor;
    NSURL *url = [NSURL fileURLWithPath:[urlsOfVideos objectAtIndex:self.pageControl.currentPage]];
    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:url options:nil];
    cmp = [AVMutableComposition composition]; 

    AVMutableCompositionTrack *trackA = [cmp addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    AVAssetTrack *sourceVideoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
    [trackA insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:sourceVideoTrack atTime:kCMTimeZero error:nil] ;

    animComp = [AVMutableVideoComposition videoComposition];
    animComp.renderSize = CGSizeMake(320, 480);
    animComp.frameDuration = CMTimeMake(1,30);
    CALayer *parentLayer = [CALayer layer];
    CALayer *videoLayer = [CALayer layer];
    parentLayer.frame = CGRectMake(0, 0, 320, 480);
    videoLayer.frame = CGRectMake(0, 0, 320, 480);
    [parentLayer addSublayer:videoLayer];
    [parentLayer addSublayer:aLayer];
    animComp.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];
    AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [asset duration]);
    AVMutableVideoCompositionLayerInstruction *layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:trackA];
    //[layerInstruction setTrackID:2];
    [layerInstruction setOpacity:1.0 atTime:kCMTimeZero];
    instruction.layerInstructions = [NSArray arrayWithObject:layerInstruction] ;
    animComp.instructions = [NSArray arrayWithObject:instruction];
    [self exportMovie:self];

这里是导出代码

-(IBAction) exportMovie:(id)sender{
NSArray *docPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *tempPath = [docPaths objectAtIndex:0];
NSLog(@"Temp Path: %@",tempPath);

NSString *fileName = [NSString stringWithFormat:@"%@/output-anot.MOV",tempPath];
NSFileManager *fileManager = [NSFileManager defaultManager] ;
if([fileManager fileExistsAtPath:fileName ]){
    //NSError *ferror = nil ;
    //BOOL success = [fileManager removeItemAtPath:fileName error:&ferror];
}

NSURL *exportURL = [NSURL fileURLWithPath:fileName];

AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:cmp presetName:AVAssetExportPresetHighestQuality]  ;
exporter.outputURL = exportURL;
exporter.videoComposition = animComp;
exporter.outputFileType= AVFileTypeQuickTimeMovie;
[exporter exportAsynchronouslyWithCompletionHandler:^(void){
    switch (exporter.status) {
        case AVAssetExportSessionStatusFailed:{
            NSLog(@"Fail");
            break;
        }
        case AVAssetExportSessionStatusCompleted:{
            NSLog(@"Success");
            break;
        }

        default:
            break;
    } 
}];

}

- Maximilian Litteral

---

请使用图层数组而不是单独的图层 -> myVideoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayers:[NSArray arrayWithObjects:videoLayer, nil] inLayer:parentLayer]; - Jiulong Zhao