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

[Oded Shimon]

On Thu, May 19, 2005 at 08:55:02PM +0200, Thorsten Pferdek?mper wrote:
> 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.

Just a hunch, try 'b = a+0.5'. With 'a = b' You get an error before the 
encode even starts i assume?

- ods15