在尝试了几件事之后,我终于找到了一种工作方法。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到这个空白视频层。然后将其导出并合并原始资产(视频)和导出的资产(资产)并导出最终资产(视频)。希望对您有所帮助。
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;
}
}];
}
现在有一个带有叠加图像的视频资产。唯一要做的就是将原始视频和导出的视频资产结合起来。导出的资产应该是底层,原始资产应该是顶层。