Resizing algorithms (Was Re: [mythtv] Ideas for high quality TV-out)

Kristof Pelckmans kristof.pelckmans at antwerpen.be
Tue Jun 29 17:29:09 EDT 2004


Quoting Ed Wildgoose <lists at wildgooses.com>:

> There are also already hooks to do a lot of clever filtering in Myth,
> for example I would be interested in a higher quality resizing
> algorithm.  This would significantly boost sharpness, and most of the
> hooks have already been added to do even this

What kind of resizing algorithms were you thinking about ?

I implemented a very easy resizing algorithm that detects black borders.
However, in order to use it, one would have to change the format (width,
height, aspect) of the recorded picture.

There would be two solutions :
1) Do not change the format, but put some extra info in each frame so the video
output handlers could scale properly.
2) Change the format _while_ recording.

I think the best option would be the second, since it would require no adaptions
to osd code. Judging from the code, someone must be doing this, since the
NuppelVideoPlayer detects changes in width, height or aspect. I believe it is
done in dvb, but I can't seem to find it...

My capture device is a plain old sdtv card, so I'm using NuppelVideoRecorder.

Does anyone have any idea how to deal with this issue ?

I also put some suggestions in the following post :
http://www.gossamer-threads.com/lists/mythtv/dev/74671

Thanks for any info !

Kristof




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