[libdv-dev] Re: horrible frames

[Dan D. <dde...@co...>]

(I dropped linux1394-devel from the recipients since it is really
off-topic.)

Also, check out http://deinterlace.sourceforge.net/ This is Windows code,
but you re-use the core functions, which are apparantly high quality.

From: "Arne Schirmacher"
> The mjpeg project has a decent de-interlacer. I wrote a brief article on
> this software on my website (
> http://www.schirmacher.de/arne/dvgrab/index_e.html ), but I did not
mention
> the de-interlacing functions.
>
> My understanding of the interlacing in DV is that every frame in DV is
> actually two interleaved video frames where every other row has been
> omitted. So a non-interlaced frame could be made by taking every other row
> and duplicating it in two consecutive rows (to retain the w/h ratio) into
> the destination buffer.

The "two interleaved video frames" are called fields. Interlacing captures
inter-field motion, which is why deinterlacing is not so simple.

> I would like to have such a function in the libdv code. I could easily
> duplicate it in the Kino code, but if interlacing is a feature of DV, then
> libdv should have code to de-interlace it.

I do not agree that libdv should do it. It is not really a feature of DV; it
is a feature of the analog video signals that DV compresses. Also, other
analog video capture sources (LML-33) have interlacing too. There are many
deinterlacers out there. Broadcast and GIMP have one. Gstreamer should have
one if it does not.

Deinterlacing and scaling are things I have been thinking about in Kino as
well. I recently asked libdv-dev about built-in scaling, to which the answer
is not so simple. However, I do not advocate implementing these into Kino.
This is just another example of how Kino has a monolithic architecture and
should be ported to gstreamer.

> I am not an mpeg expert at all, but I think that the mpeg code would
> compress de-interlaced frames better than interlaced ones, because the
> latter have more rough looking features which do not compress that good.
> But this is just a guess.

Yes, and you do not need to be an expert to notice it! The inter-field
motion creates a "blinds effect" that compresses something horrible.

> Also, when saving a single frame the de-interlaced image would look much
> better. Maybe the two half frames can even be processed and overlaid with
> some existing image processing library.
>
> Arne
> -----Original Message-----
> From: David Bonneville
> Sent: Monday, May 21, 2001 2:35 PM
> To: lib...@li...; lin...@li...
> Subject: horrible frames
>
> Hi all,
>
> I have some problems when I use Frame::ExtractRGB() (dvgrab's code). I got
> some interlaced frames as you can see at
> http://www.idiap.ch/~bonnevil/images
>
> Do you have/know this problem ?
>
> I am  also trying to use Frame::ExtractYUV() but it seems that I've not
> find
> the correct format yet. If somebody know it or has ever used it before,
> please tell me what to do.
>
> Thanks
>
> David
>
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