[MPlayer-users] Re: Blotchy Colors (revisited)

D Richard Felker III dalias at aerifal.cx
Wed Apr 2 05:33:07 CEST 2003

On Tue, Apr 01, 2003 at 06:57:57PM -0500, spowers at inland.k12.mi.us wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> >Scan converters generally suck
> DOH!  (but I'm starting to agree...)
> >You might have better results if you
> >set the video mode to exact NTSC (or PAL
> >if you're using a PAL TV)spec, but it would
> >be much better if you could do this and then bypass
> >the scan converter altogether, just using a simple
> >piece of hardware to convert the colorspace and
> >generate the right luma and chroma signals.
> I hate to even ask -- but how does one go about this?  Are you talking a
> simpler scan converter circuit for VGA -> SVIDEO ?

Well it's not called a scan converter since it doesn't mess with the
sync pulses or any buffering; it just converts RGB to NTSC luma/chroma
signals for svideo or composite. Unfortunately these are very rare
nowadays since (a) you need to play around with setting your computer
up for the exact right timings, which newbies/windows users can't do,
and (b) all the companies making this stuff would rather sell you an
insanely expensive scan converter needed to get good quality with scan
conversion, whereas $15 of simple equipment could do the same thing if
you set your video card to output the right timings.

> Also, what exactly do you mean by setting the video mode to exact NTSC? 
> Are you talking about the linux framebuffer or X11 being set somehow, or
> rather an option in mplayer itself?

FB or X11 video mode, whichever you use. Start with basic "60 Hz" VGA
640x480 and see if that works well. If not, enable interlacing and cut
the dot clock in half. Note that if you do that, most monitors will
NOT sync to the signal, and it could damage crappy monitors if you
connect them to such a signal. Good monitors handle it gracefully, but
I just want to warn you so you don't break anything without knowing
the risks.

> Someday, I'll convince my wife that we need to get a CRT projector for the
> living room, but until then, I'm stuck with a TV. :)
> I really am willing to read documentation, and or buy hardware  -- I'm
> just frustrated because I've grepped and googled a bunch, and still have
> an odd looking picture on my TV.  (BTW, this is my second scan converter,
> and both have the same problem, except that with the last one, it was also
> too dark...)

This site shows how to make what you need:


Maybe you can find someone to make one for you. :))) The chip they
recommend is discontinued now, but there's a new model that's
identical, which I'm using in a similar (but much simpler) circuit for
my tv output (I simplified it since I knew I'd have a plenty control
over the sync pulses myself and wouldn't need the extra stuff to get
them right).

BTW don't ask me to make it -- I don't have the right equipment for
doing PCB's and surface-mount IC's, so my device is a very delicate

BTW2, you might be better off just buying a G400. :)) I sure would
have been, but it was fun learning about RF circuits I guess...


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