[FFmpeg-user] Image extraction broken with ffmpeg, but not with mencoder. How can I fix this?

James Board jpboard2 at yahoo.com
Thu Sep 5 19:47:08 CEST 2013

>> Okay good.  All I need is a formula for determining what the timestamp

>> is a for a specific frame (and vice versa).  What is that formula?
>The formula is: timestamp. The timestamp is what identifies the frame, there
>is nothing else, you should not be trying to compute it from anything else.

That's not a formula.  In order to use timestamps for editing, I need to
be able to determine the timestamps for the start of each cut, call it frame S,
and the end of each cut, call it frame E.  I'm willing to try your method here.
Just tell me how to calculate the timestamps for S and E.  Not only are you 
ignoring the question, you are insulting me for asking, and I have no idea why
you are pissed off.

>> Really?  You might want to rewrite the Wikipedia page on floating-point
>> numbers:
>>     http://en.wikipedia.org/wiki/Floating-point_arithmetic
>> Those guys think floating-point numbers aren't exact.
>Do not try to play smart, you are losing. 

I was joking.  You miss the point.  If I want to start my edit on the 10th frame, for 
example and my video is 29.97 fps, then I divided 10 by 29.97 to get the timestamp.
That number is on my Windows 7 calculator is
It will be a slightly different number on a different calculator.
What happens if I use timestamps, as you say, and I round off and use 0.33366700?
Does ffmpeg round up to the closest number, or down to the previous frame?  Does it
consistently do the same thing?  That's the problem.  Frame numbers don't have this problem.

>Well, I will not waste any more time on you. Good luck.

Yes.  Clearly an impedance mismatch between us.  No hard feelings.  Thanks for trying.

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