该CMPixelFormatType常数是的一个子集CVPixelFormatType常数 。
此外，在CMPixelFormatType评论，它说：
在一般情况下，corevideo的CVPixelFormatType常数可能太习惯。
什么是这两组常数的区别？ 为什么是CMPixelFormatType常量只有一个子集CVPixelFormatType常数？ 他们是特殊的？
Answer 1:
Update: Nope, kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange (not defined in CMPixelFormatType) is also supported.
My guess is that the subset of pixel formats defined by CMPixelFormatType are the ones that are actually supported in macOS/iOS whereas the pixel formats defined by CVPixelFormatType are all the known pixel formats in the world.
This is hinted in the Pixel Format Identifiers documentation:
Core Video does not provide support for all of these formats; this list defines only their names.
文章来源: Difference between `CMPixelFormatType` and `CVPixelFormatType`?
