Snapshot image capture off a composite video stream

Hi,

I have a project feasibility question that I wish to put across to you guys...

I would like to capture a snapshot (BMP or JPEG) off a composite video stream and save it to SD Card. Ages ago I used to have a video printer which took composite video in and a simple print button would thermally print the image to paper. However, I would like to improve this so that I can just save the snapshot to SD Card and view them on a PC (and be able to print them in colour!).

Is there a cheap standalone method to do this? Im not overly worried about compression but it would need to be standalone and not plug into a PC. Any ideas????

notorious: Any ideas????

None involving an Arduino.

The only approaches I can think of would be based on a video decoder and frame buffer. Which implies either dedicated hardware made for the purpose, or something like a PC which has this capability already.

What's the objection to using a PC? Would a laptop be acceptable? Or a tablet? Or an embedded PC?

Thanks, a laptop or PC would be out of the question due to the small size of the unit and the fact its required to run off batteries. Ideally I need a widget in a box with a BNC in and out, with an SD Card slot.

Back to the drawing board....

I found this on the internet:

http://www.amrphones.com/snappy/faq.html

Apparently they dont make it anymore and by the looks of it these guys had a custom chip made. Cloning one of these to write to SD Card would be the way, but where to start?

notorious: I found this on the internet:

http://www.amrphones.com/snappy/faq.html

Apparently they dont make it anymore and by the looks of it these guys had a custom chip made. Cloning one of these to write to SD Card would be the way, but where to start?

I own one of those - bought it when it first came out (and quite impressive for what it did at the time) - but unless you have a rich investor or something else up your sleeve (that, or a ton of time on your hands, as well as being an expert in FPGA/VHDL design) - you won't be cloning it.

If I were you, I would start by going back about 20-30 years, and looking at old BYTE magazines, Steve Ciarcia Circuit Cellar articles, and other old computer magazine articles (and books) from the 1970s and 1980s on "video digitization" to get an idea of what is going to be involved just in decoding a composite signal (and you haven't specified PAL or NTSC; but since you are in the UK, I assume PAL?) - not to mention capturing it.

Once you have a handle on that, you might want to then look into the Nootropic Design Video Experimenter shield (and code - which is based on the TVOut Library) to learn how it works to capture a low-res B/W version of the signal (color is another thing altogether):

http://nootropicdesign.com/ve/

Ultimately, you're not going to do what you want to do with the Arduino by itself; you might be able to use it for control of some chipset meant for this purpose (good luck finding and purchasing that chipset, though - I am sure such a thing exists, but it probably isn't sold by 1s and 2s for hobbyists). If you wanted to do this "directly", you'd be better off using a small embeddable PC board (ARM-based, most likely, running Linux), and using that (along with a composite to RGB analog conversion IC, running that to an external or on-board ADC channels) to write custom software to digitize and store the image to your SD card. Even that, with the simpler hardware, is going to be a software challenge like you wouldn't believe (well, you'll probably understand once you learn about how it was done in "the old days").

I will say this - if you are going for PAL composite digitization, it is supposedly simpler to digitize (and generate) a proper PAL signal than an NTSC signal (that's all relative, though).

Good luck with your project. :)

Only way to do it with AVR/Arduino I could think, is under-sampling, which imply "still" image video capture, approximately 2 sec per one pics ( image shouldn't change during this time)

I've got a snappy from the old parallel port days. Also have several B/W conextant quickcams. Those were the days of cuseeme and such.

zoomkat: I've got a snappy from the old parallel port days. Also have several B/W conextant quickcams. Those were the days of cuseeme and such.

I can go one better: In my TRS-80 Color Computer collection from when I was a kid, I have a DS-69 (I think that's right) video digitizer cartridge. You plugged it into the cartridge slot (well, in my case, since I had a floppy drive, I'd plug it into my multi-pak interface), and hooked up a composite source to it (I used my dad's video camera). You then ran the digitizer program, and waited. Took a while to digitize an image, considering you were running at a blazing 1 MHz speed. What you got in the end was a 2-bit grayscale 256 x 192 image (or something pitiful like that).

Later I had a digitizer for my Amiga (using this b/w tube-based camera - with color filters, you could do color images), then when I moved to my PC I got the Snappy when it came out (the principal founders of Play, Inc were behind the NewTek video toaster on the Amiga, IIRC - so I trusted it would be a good product).

What do you think of the images from the snappy? Ive seen one on ebay, was thinking of buying one and seeing if I can convert the parallel output to SD?

Ive been looking into this and it seems there is some serious work required here....