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Malcolm
26th May 2003, 16:14
Hi,
i know, the following can easily be achieved with existing functions. But this is a request about speed improvement.

I'd like to use filters only on certain regions of the video. for example if i have a video with borders (16:9 -> 4:3, TV-crop, ...)
i'd like do something like

crop(16,80,-16,-80)
convolution3d()
# or any other filter
addborders(16,80,16,80)

(because filtering is only necessary in parts that are not black)

But i'd like to do that without having to do crop + addborders before and after. (Because i guess this is unnecessary timeconsuming)

I could imagine that it's faster if there's a filter which selects only a region of the video (like crop) and passes this to any other filter. But the result would have to be the complete (uncropped) video.

Maybe like this

region(16,80,-16,80).convolution3d()


I hope such a filter would bring a certain speed improvement over crop + addborders.

bye,
Malcolm

WarpEnterprises
26th May 2003, 23:20
AFAIK crop and addborders are VERY fast as they try to not change the actual video data (offsetting only).

Richard Berg
27th May 2003, 00:00
Crop does what you want: like WarpEnterprises said it works in-place. (That's why it's so "helpful" in finding pitch/width bugs.) There should be no need to add borders afterward, unless you're making a VCD or similar.