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Unofficial VirtualDub Support Forums > VirtualDub Development Forum > Saving Images For An Index


Posted by: Kjella Dec 7 2002, 04:18 AM
Hi!

I'd like to use VirtualDub to create a set of frames that I could use as basis for a movie index. However the "Save image sequence..." dialog only allow me to save every frame. I'd like the option of specifying how many frames it should save, either as a fraction (1 in 100 frames saved) or as a total. The total can also be replaced by a ratio, as 1 in every N/(n+1) frames, where N is the total and n the desired number of frames.

Implementing it should be fairly straightforward, but a bit over my skills none the less. If I want to save every k'th frame, the pseudocode would be something like:

%counter = 0;
if (%counter == k)
{
save frame
reset counter
} else {
discard frame
%counter++
}

Perhaps my math is one off here and there, and the beginning and end is a bit fishy. But such an automatic process is only a start, it'll produce some useless frames (for an index) that'll have to be removed anyway. It sure would be a lot easier than doing it manually though.

Kjella

Posted by: phaeron Dec 7 2002, 07:26 AM
All video processing options are available when saving to an image sequence -- so just set the frame rate decimation value to N in Video | Frame Rate and you will save every Nth frame.


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