[MEncoder-users] Neewbie question : need to resample avi file from 15fps to 25fps

[Jarred Nicholls]

On Mon, Jan 4, 2010 at 10:44 AM, Grozdan <neutrino8 at gmail.com> wrote:

> On Mon, Jan 4, 2010 at 4:13 PM, 7willows <7willows at dsl.pipex.com> wrote:
> > Hi,
> >
> >
> > I have twelve AVI files which were recorded at 640x480 @ 15fps recorded
> on
> > my Nikon L20 camera which I want to add onto a DVD with AVI files from my
> > Canon MV650 which records at 25fps.
> >
> > I have had a look through the MEncoder documentation but can not find
> what I
> > need.
> >
> > Could you advise on the options required to resample the 640x480 @15fps
> to
> > 640x480 @25fps ?
>
> Mencoder can't do 'real' FPS conversion. All it can do is force the
> output fps to 25 with -ofps which will duplicate frames in order to
> get the requested output fps
>

Specifically, look at the filter harddup (-vf harddup) which will provide
the duplicate frames and keep the audio/video in sync while doing so.  The
default action is just putting 0 byte frames into the stream, but by using
harddup, mencoder will actually duplicate the previous frame N times every M
frames to match the output FPS which makes it more "kosher" if you will, but
also maintains A/V sync.  As Grozdan pointed out, there's no real FPS
conversion (i.e., interpolating pixel motion between frames), just the
hackish way of duplicating frames.  If you're going from 15 -> 25 then it
might still look ok to the eye.  When you go from a low FPS to a high FPS
then the frame dup'ing makes the video look choppy/robotic.


>
> >
> > TIA
> >
> >
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