Question

我正在使用AVVideoComposition来为视频应用过滤器。它工作正常，但生成视频需要很长时间。另一方面，我注意到在不应用过滤器的情况下导出视频非常快，所以我知道应用过滤器的过程就是问题所在。

这是我用来将过滤器添加到视频中的一些代码：

此代码生成视频的合成。

public func generateComposition() -> AVVideoComposition {
    let composition = AVVideoComposition(asset: asset) {
        request in
        let source = request.sourceImage.clampingToExtent()
        self.zoomBlurFilter.setValue(source, forKey: kCIInputImageKey)

        let currentTime = CMTimeGetSeconds(request.compositionTime)
        let totalTime = CMTimeGetSeconds(self.asset.duration)
        let timePercentage = currentTime/totalTime
        self.zoomBlurFilter.setValue(timePercentage * Float64(self.blurAmount), forKey: "inputAmount")

        let imageCenter = self.centerOfFirstFace(for: request.sourceImage) ?? CIVector(x: request.sourceImage.extent.midX, y: request.sourceImage.extent.midY)
        self.zoomBlurFilter.setValue(imageCenter, forKey: "inputCenter")

        guard let blurFilterOutput = self.zoomBlurFilter.outputImage else { request.finish(with: self.compositionError); return }

        self.vignetteFilter.setValue(blurFilterOutput, forKey: kCIInputImageKey)
        guard let vignetteFilterOutput = self.vignetteFilter.outputImage?.cropping(to: request.sourceImage.extent) else { request.finish(with: self.compositionError); return }

        request.finish(with: vignetteFilterOutput, context: self.context)
    }

    return composition
}

此代码将视频导出到输出文件。

public func exportFilteredVideo(to outputURL: URL, completion: @escaping (Void) -> Void) {
    if FileManager.default.fileExists(atPath: outputURL.path) {
        try? FileManager.default.removeItem(at: outputURL)
    }

    let export = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetMediumQuality)!
    export.outputFileType = AVFileTypeQuickTimeMovie
    export.outputURL = outputURL
    export.videoComposition = generateComposition() // Commenting out this line makes it go very fast, but obviously there is no filter if I comment this line out.
    export.exportAsynchronously(completionHandler: completion)
}

以下是我正在使用的背景信息：

let context = CIContext(options: [kCIContextCacheIntermediates: false])

为了最大限度地提高CIFilters的速度和性能，我是否应采取任何措施？视频本身只有三秒钟，所以我认为不应该花这么长时间：（。

将滤镜应用于Core Image非常慢

0 个答案: