Sending files - Feature Requests - CHDK Forum
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Sending files

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Offline frank

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Sending files
« on: 05 / July / 2008, 14:52:38 »
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It would be a cool feature to exchange scripts or other files between two cameras.
Maybe there could be used the blinker firmware dump code on the sending camera and some kind of motion detection on the other camera. This could also be used for firmware dumping without having to destroy a mouse(optical sensor)
But you must have to cameras
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Big Grin
Please excuse my bad English ;-)
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Camera: A570IS      Firmware: 1.01a
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Offline RaduP

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Re: Sending files
« Reply #1 on: 05 / July / 2008, 15:06:17 »
You can read the data from the sensor every so often, so using the sensor to get the data from an LED would be really slow, maybe a few octets per second.
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Offline fudgey

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Re: Sending files
« Reply #2 on: 06 / July / 2008, 03:28:41 »
Yep, at least by reading the LCD buffers it would probably take a few minutes to transfer a couple of kilobytes.
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Offline DataGhost

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Re: Sending files
« Reply #3 on: 06 / July / 2008, 09:24:55 »
Of course, it is possible to use special encodings and send the data via the camera LCD. Example: datamatrix 2d barcodes



If the resolution is large enough (say, 8x8 pixel blocks), 1350 bits (about 169 bytes) will fit on one LCD screen and given the speed of LCDs (S5 does 40FPS with proper lighting) and some good focus, it should be possible to transfer at least 1 kB/s. I'll look into it because this may be valuable indeed :)

This could also be useful for transferring files from a PC (LCD) to a camera without having to power it down, (remove the tripod attachment,) open the battery compartiment, remove the SD card, plug it into a cardreader, mount it, create a file, save it, sync, umount, take it out, put it in the camera again, (reattach the tripod attachment,) power up camera, spend some time setting your precious MF settings and overrides and finally figuring out you made yet another mistake.
« Last Edit: 06 / July / 2008, 09:27:58 by DataGhost »
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Offline LjL

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Re: Sending files
« Reply #4 on: 06 / July / 2008, 09:50:15 »
Yeah, it'd be possible to send at relatively high speeds using 2D barcodes... but what about receiving? Most barcode readers I know (look at Zebra, by the way, if you want an open-source one as reference) aren't so lightening fast...
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Offline jetzt

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Re: Sending files
« Reply #5 on: 06 / July / 2008, 11:00:03 »
Interesting I think, but receiving isn't trivial, and might be the real speed problem.
But I think a speed of a kilobit is doable (for script transfers or only to sync the settings this would be more than ok).
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Offline DataGhost

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Re: Sending files
« Reply #6 on: 06 / July / 2008, 12:32:29 »
Well, I'm working on some detection now (own implementation) and it's not really looking too easy... but speed shouldn't really be an issue. It should be quite easy to detect at least the outline and maybe the first 8 bits (indicating a sequence number maybe?) in realtime, so it should be possible to get at least 10FPS (currently I'm at 160 characters per frame, no ECC whatsoever yet) so that should work out to about 1 kB/s. If it's really impossible to actually read *all* frame data in real-time, we can just store the frames and process them later, so the actual sending takes just a couple of seconds. It is very important to hold the camera straight and steady while the transfer is going on, though, and barrel distortion is a [admin: avoid swearing please] as well. It's hard but certainly not impossible.

So far I came up with a somewhat usable resolution for the source image and I managed to detect the leftmost black bar, though it doesn't necessarily detect the full length yet, etc etc etc.
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Offline RaduP

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Re: Sending files
« Reply #7 on: 06 / July / 2008, 12:36:23 »
The 'look at the other camera's LCD' method won't work, because it is unidirectional, so there is no way to do stuff such as synchronizing the transfer, ask for the data again if it is bad, and so on.
I think that the only viable way would be through USB, if someone can find out how to have raw access for the USB controller.
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Offline LjL

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Re: Sending files
« Reply #8 on: 06 / July / 2008, 12:49:33 »
To confirm my identity as Mr Obvious... why not just zoom in to the length when barrel distortion is minimal?

And remember that this isn't something that has to be printed in black and white like a normal barcode - i.e., you can color encode...

White balance is going to be an issue, but as long as you just encode red, green and blue "on/off" it should be workable, I guess.

If you just divide the screen in, say, 4x4 parts, and encode like that, you get 180 bytes per second... I've seen faster acoustic couplers, but still :D

(How about acoustic coupling, anyway?)
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Offline RaduP

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Re: Sending files
« Reply #9 on: 06 / July / 2008, 12:52:33 »
AFAIR, acousting coupling doesn't work because there is no way to directly read the microphone data..
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