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Subject: Re: Pal to jpeg - graber and converter?
Date: Sun, 29 Sep 2002 18:44:56 +0100
NNTP-Posting-Date: Sat, 28 Sep 2002 19:07:41 BST
Organization: ntl Cablemodem News Service
Erik Lindstein wrote:
> Are there any IC that i can use this way:
> Connect an pal signal to the IC 75ohm video terminator.
> The use an microcontroller (Atmel AVR series ore something)
> Trigg the "Videograber" and then read out the jpeg data from the IC
> and store it in an internal eeprom om the microcontroller.
> Is this a fantasy project ore can it be done this simple?
> if so, wath IC/ICs do i use? for the video part..
I'm doing something similar at the moment, except my project has a
network controller as well, to send the JPEG data down the wire.
You can't do it (to my knowledge) with one chip, but I've got a Phillips
SAA7110A video decoder (PAL, SECAM & NTSC) which links directly (no
glue) to a Zoran ZR36060 JPEG encoder/decoder chip. The Zoran has a host
interface with a 1k buffer that needs to be serviced by a
microcontroller or CPU. For this, I intend to use a Rabbit RCM3200,
which has a built-in 10/100 ethernet interface and can send ~500k/sec
down the wire.
It should really be just a matter of wiring - after reading the
datasheets. The Phillips chip is controlled by an I2C bus (the rabbit
has an I2C library), the Zoran via registers. Get the comms right, and
I'm hoping it'll all fall into place :-)
The beauty of the ZR36060 is that it needs no external SRAM - it
contains a built-in SRAM line-buffer and does all the encoding on the
fly. This does mean you can't get full PAL res, since it can only
encode a field at a time - this is why "Motion JPEG" was created - each
field is compressed as a separate image, and combined to form the final
image at the destination.
The chips are reasonably costly in small quantities - the SAA is about
20 pounds, and the zoran around 40 pounds (UK).
Hope this helps,