为视频添加滤镜效果的思路如下
1.使用AVPlayer + CIFilter进行渲染
参考文档 Processing Video with AV Foundation
关键代码
//1
AVURLAsset *asset1 = [AVURLAsset assetWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"sample_clip1" ofType:@"m4v"]]];
//2
CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];
AVVideoComposition *composition1 = [AVVideoComposition videoCompositionWithAsset:asset1 applyingCIFiltersWithHandler:^(AVAsynchronousCIImageFilteringRequest * _Nonnull request) {
//3
CIImage *source = request.sourceImage.imageByClampingToExtent;
int currentTime = request.compositionTime.value / request.compositionTime.timescale;
if (currentTime < 3) {
[request finishWithImage:source context:nil];
} else {
[filter setValue:source forKey:kCIInputImageKey];
//4
CIImage *output = [filter.outputImage imageByCroppingToRect:request.sourceImage.extent];
[request finishWithImage:output context:nil];
}
}];
//5
AVPlayerItem *item = [[AVPlayerItem alloc] initWithAsset:asset1];
item.videoComposition = composition;
步骤1：读取本地的视频路径
步骤2：设置CIFilter效果，使用AVVideoComposition处理渲染过程
步骤3：获取视频帧并转换成CIImage以供CIFilter进行渲染，可以设定渲染的时间
步骤4：将渲染完成的CIImage返还给request
步骤5：将视频组成装入播放文件中播放即可
存在问题：
1.播放与导出时加入滤镜的情况下cpu占用100%
实例参见 github Demo
