[MEncoder-users] Trying to cut at exact frames (-hr-edl-seek etc.)

[Thorsten Pferdekämper]

Hi,
I have tried to use mencoder to cut videos at exact frames (with some success, 
thanks to Oded). As EDLs only allow to enter time intervals and not frame 
intervals, I have tried to determine a formulae to compute EDL entries from 
ranges of frames I want to keep. 
Here is what I have found:

Let d be the duration of one frame (i.e. 1/framerate). 
Let [a,b] be the frame interval you want to keep. (Starting to count with 0)
Let l be something bigger than the length of the video in seconds
Then you need two entries in the EDL file:
	0.00		a*d	0
	b*d		l	0

I tried it out and it works. (It does not look like to be very hard to 
believe...)
At least, this works if b is really bigger than a. with a=b, it does not work. 
I would have expected, that I will get exactly one frame in this case, but I 
get zero frames. With b = a+1, I get two frames (a and b). 
So, what does this mean? It simply means that it is impossible to cut out 
exactly one frame (or every second frame or something like that). Perhaps 
this is not very important and rather academic, but I thought it was worth to 
be mentioned.

Regards,
	Thorsten