[MEncoder-users] How does one interlace progressive content?

[RC]

On Sun, 5 Aug 2007 03:08:15 +0200
Grozdan Nikolov <microchip at chello.be> wrote:


> so how are interlaced PAL DVDs made? I have a couple of them here and
> mplayer  always reports 25fps frame rate

They are interlaced to begin with, NOT converted from progressive to
interlaced.  

I can't imagine what you hope to accomplish by converting progressive
video to interlaced, but I can assure you it won't have any positive
effects at all.

> I did a small test here with tinterlace=4 on a 25fps progressive PAL
> DVD and  during encoding, mencoder printed a lot of duplicate frames
> but the result  was a 25fps file (or at least that's what mplayer and
> avidump reports). The  file played just fine without sync issues and I
> could see the interlacing

If you set -ofps mencoder will skip/duplicate frames as needed to get
the framerate you've set.  Your video, however, is now double-height
(eg 720x1152) and pretty much useless.