缩放后，CIIMAGE CVPIXELBUFFER为零
我正在使用avvideopomposition api从本地视频中获取ciimage s，并且在缩放ciimage之后，我得到了> nil尝试获取cvpixelbuffer。
在缩放源框架之前，我要获得原始帧cvpixelbuffer。
有什么原因是缓冲区 nil 在缩放？
样本：
AVVideoComposition(asset: asset) { [weak self] request in
let source = request.sourceImage
let pixelBuffer = source.pixelBuffer // return value
let scaledDown = source.transformed(by: .init(scaleX: 0.5, y: 0.5))
let scaledPixelBuffer // return nil
})
I'm using the AVVideoComposition API to get CIImages from a local video, and after scaling down the CIImage I'm getting nil when trying to get the CVPixelBuffer.
Before scaling down the source frame, I'm getting the original frame CVPixelBuffer.
Is there any reason the buffer is nil after scaling down?
Sample:
AVVideoComposition(asset: asset) { [weak self] request in
let source = request.sourceImage
let pixelBuffer = source.pixelBuffer // return value
let scaledDown = source.transformed(by: .init(scaleX: 0.5, y: 0.5))
let scaledPixelBuffer // return nil
})
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（1）
我认为您的样本中的最后一行是不完整的。您的意思是
让ScaeledPixelBuffer = ScaledDown.pixelBuffer吗？如果是这样，则是的，这将无法正常工作。原因是pixelbuffer属性仅当直接从cvpixelbuffer直接创建ciimage时才可用。从文档中：传递给组成块的
ciimage是由Avoundation提供的像素缓冲区创建的。但是，当您应用过滤器或对其进行转换时，需要使用cicontext将结果图像明确地渲染到像素缓冲区中，否则您将不会得到结果。如果要更改构图所使用的视频框架的大小，则可以改用
avmutableVideOpomposition，然后将其RenderSize设置为您所需的大小，然后才能初始化。I think the last line in your sample is incomplete. Did you mean
let scaledPixelBuffer = scaledDown.pixelBuffer? If so, then yes, this won't work. The reason is that thepixelBufferproperty is only available if theCIImagewas created directly from aCVPixelBuffer. From the docs:The
CIImagethat is passed to the composition block was created from a pixel buffer provided by AVFoundation. But when you apply a filter or transform to it, you need to render the resulting image into a pixel buffer explicitly using aCIContext, otherwise you won't get a result.If you want to change the size of the video frames the composition is using, you can use a
AVMutableVideoCompositioninstead and set itsrenderSizeto your desired size after it is initialized: