[MPlayer-users] Scaling interlaced video for DVD playback

[Fabio Papa]

On Friday 14 November 2003 12:28, Neil Radisch wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
>
> > The resulting video is still interlaced, but with more thick lines, which
>
> I
>
> > think is ok given the rescale operation.
>
> No it's not ok. The "thick lines" means you've altered the interlace and
> it will not display properly.
>
> In order to compress interlaced material you either have to use an encoder
> that really understands interlace, or fake it.
>
> As for the first option, I don't believe any of the opensource encoders
> under linux truly support interlace, but I may be wrong here.
I also thought of that.

>
> As for faking it, you might have to write your own compress app. I'm not
> sure what mencoder's capabilities are as I've never use it. But regardless
> you
> either need to
>
> 1) Seperate out the fields. Take the source and seperate it into two
> fields. Compress
>     the fields independently. On playback, decode the fields then weave
> them back together
>     as a frame. You'll need to write your own compress and playback app for
> this.
> 2) Fake the width. Someone (Billy Biggs?) suggested this to me. Feed the
> interlaced frame
>     into the decoder, but tell the decoder that the frame is twice as wide
> and half as high as
>     it really is. This stops the encoder from "smearing" the interlace and
> screwing up the motion.
All this implies the use of a software decoder, while I need the file to be 
played on a normal set-top player. Never mind, you clarified the matter well 
enough: I must wait until (if ever) ffmpeg develops their mpeg encoder a 
little bit to include interlaced support.
Thanks anyway!

>
> Neil
>
>
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-- 
Fabio Papa
Engineering division
Machining Centers Manufacturing S.p.A.
viale F. e G. Celaschi 19 - Vigolzone (PC) Italy