From owner-freebsd-multimedia  Fri Jun 26 03:02:05 1998
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Date: Fri, 26 Jun 1998 11:01:41 +0100
From: Roger Hardiman <roger@cs.strath.ac.uk>
Organization: University of Strathclyde
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To: Amancio Hasty <hasty@rah.star-gate.com>
CC: freebsd-multimedia@FreeBSD.ORG
Subject: Improvements to the bt848 driver - SW Pan and Zoom.
References: <199806260910.CAA00703@rah.star-gate.com>
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Hi all.

I've been thinking about an improvement to the bt848 driver.
The same could be made to the meteor driver too.

I'd like to grab from a sub-section of the video image.
This allows the software pan and zoom functions you can get with
a fixed camera with a wide angle lense.

Currently, the bt848 driver captures the full NTSC (or PAL) image
and scales it down to the desired image size, say 192x128 pixels.

+----------+
|aaaaaaaaaa|
|aaaaaaaaaa| to +---+     FULL NTSC to 192x128
|aaaaaaaaaa|    |aaa|
|bbbbbbbbbb|    |bbb|
|bbbbbbbbbb|    +---+
|bbbbbbbbbb|
+----------+

I would like to grab a sub-portion of the NTSC (or PAL) window
and optionally scale that.
So, I could grab a real 192x128 chunk from say the bottom left corner of
the video image.

+----------+
|aaaaaaaaaa|
|b+--+ bbbb| to +---+     SMALL WINDOW FROM NTSC to 192x128
|c|cc| cccc|    |ccc|
|d+--+ dddd|    +---+
|eeeeeeeeee|
+----------+


Now all these things can be performed by grabbing a full image and
then copying the parts you need. However, the hardware still
has to cope with moving a full video image around.


For the bt848 this needs some new IOCTLS and changes to the
dma_progs.

Any comments on this?

Roger Hardiman
Strathclyde Uni Telepresence Group
this would

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