Dual PAL video input -> cropped, split output

[Quack]

Hi,

I am trying to find (or make if i can find the right chips to make it simple
enough) a device that will take 2 out of sync PAL video inputs and create a
single PAL output comprised of both signals split horizontally (in a cropped
fashion, not squashed).

Without going into too much detail, there is no way around it, vertical
splitting or 'squashed video' is not an option. This is for a very specific
purpose.

I have tried googling around but i cant find what im looking for, but i
could be using the wrong terminology. Perhaps its a simple normal thing to
want to do.

Any hints anyone ?

Thanks!
Alex.

 

[Quack]

To make a horizontal split, you need a video switch, toggled at twice
the field rate, i.e. at 100 Hz for PAL. This is not very difficult. But

Yes i considered this, but i cant guarantee the cameras will be insync.
I have all parts for this already and could knock it out quickly.

if the video streams are out of sync, you need a genlock as well, and
that is more ambitious.

The 'genlock' you mention, this would be a function of the cameras as i
understand it, and not of the 'device in the middle' ?
As a compromise we could have the cameras in-sync as a requirement, but this
is not the ideal solution

Thanks
Alex.

 

[John Woodgate]

I read in sci.electronics.design that Quack <alex+google@vuetec.com>
wrote (in <33ss4iF42sqcbU1@individual.net&gt about 'Dual PAL video input
-> cropped, split output', on Mon, 3 Jan 2005:

Hi,

I am trying to find (or make if i can find the right chips to make it simple
enough) a device that will take 2 out of sync PAL video inputs and create a
single PAL output comprised of both signals split horizontally (in a cropped
fashion, not squashed).

Without going into too much detail, there is no way around it, vertical
splitting or 'squashed video' is not an option. This is for a very specific
purpose.

I have tried googling around but i cant find what im looking for, but i
could be using the wrong terminology. Perhaps its a simple normal thing to
want to do.

To make a horizontal split, you need a video switch, toggled at twice

the field rate, i.e. at 100 Hz for PAL. This is not very difficult. But
if the video streams are out of sync, you need a genlock as well, and
that is more ambitious.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Tim Wescott]

Quack wrote:

To make a horizontal split, you need a video switch, toggled at twice
the field rate, i.e. at 100 Hz for PAL. This is not very difficult. But


Yes i considered this, but i cant guarantee the cameras will be insync.
I have all parts for this already and could knock it out quickly.


if the video streams are out of sync, you need a genlock as well, and
that is more ambitious.


The 'genlock' you mention, this would be a function of the cameras as i
understand it, and not of the 'device in the middle' ?
As a compromise we could have the cameras in-sync as a requirement, but this
is not the ideal solution

Thanks
Alex.


It sounds like what you really want is to be able to read the video

streams into a pair of frame buffers so you can sync them up, then read
them out as described -- the nice thing about using the frame buffers is
you no longer need to be genlocked, but you can get into some serious
work to make it happen.

If you haven't already try searching for "video effects".

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com