[FFmpeg-user] Image extraction broken with ffmpeg, but not with mencoder. How can I fix this?
nicolas.george at normalesup.org
Thu Sep 5 19:12:33 CEST 2013
Le nonidi 19 fructidor, an CCXXI, James Board a écrit :
> But I have a unique and unusual requirement. I want to do frame-exact
That is in no way unique or unusual. You are just doing it wrong.
> I split the file into a sequence of frames so I know at exactly which
> frame the cuts should begin and at which frame they should end.
You should not be doing that.
> 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.
> >> 3: Timestamps are floating-point numbers, and floating-point numbers are
> >> not exact.
> >That is untrue.
> Really? You might want to rewrite the Wikipedia page on floating-point
> Those guys think floating-point numbers aren't exact.
Do not try to play smart, you are losing. There was two parts in your
> Bummer. You had my hopes up earlier when you said each frame can
> be identified by it's timestamp. So which is it?
The timestamp, no more no less.
> Either way, unless I can uniquely and consistently determine the frame
> number from the timestamp, and also determine the timestamp from the
> frame number, I don't see how I can do frame exact editing with time stamps.
> That's why I use frame numbers.
Well, I will not waste any more time on you. Good luck.
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