Re: Averlogic AL250 and scan doubling

"Keith M" <keithvz@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:9X%Gj.4590$N_5.2704@xxxxxxxxxxx
Does anyone have experience with the Averlogic AL250 Video Scan Doubler
IC?

Not directly but doing various resolution video deinterlacing to various
resolution
LCD panels.

Data*** is here

http://www.ortodoxism.ro/datasheets/Averlogic/mXvqxzx.pdf

and Application notes

http://www.ieechina.com/Upload/Tech/200405191539390937.pdf

As far as interfacing to this IC, do think it's out of reach for a
beginner? They don't provide a schematic for their evaluation board,
but the parts list doesn't look too crazy.

Depends on definition of beginner as various things with video are beyond
most beginners.

It has I2C control, which should be easily accessed from any
microcontroller.

I've got a simple application for the IC, and it would be setup in a
fixed configuration mode. There's no need for multiple connectors,
multiple display modes, etc. One NTSC input(~15khz), one VGA
output(~31khz).

For a fixed input to LCD you will have to use NTSC YUV mode and note
that the effective 24 bit colour input is cropped to 16bit colour by the
chip.
Anything non-square pixel or using 601 formats requires a CRT that hopefully
can sync to that rate. Anything using an LCD would need register setups to
CROP the image.

In general, is scan doubling/de-interlacing a hard thing(TM) ? This IC
does some fancy things, but would simply sampling one side, buffering,
and then outputting the other side generally work?

Line doubling is one way to go. This device sort of claims interpolated
doubling
which is usually better method for handling different resolutions. But it
only
partially does this.

As this chip has to use an external video decoder/digitiser, the I would
look at other alternatives. Logic Devices make various chips for digital
processing which can be
setup quite easily to do various interpolation schemes, even changing
horizontal
resolution for full image display.

A good resource for this type of thing is the book

Video Demystified (I have first and fourth editions)
By Keith Jack (ex Brooktree engineer)

ISBN 0-7506-7622-4

Thanks

Keith
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