Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

scanning and downloading at the same time

Everything camera related. Includes triggers, batteries, power supplies, flatbeds and sheet-feeding scanners, too.
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Drake Ravensmith
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E-book readers owned: Kindle 3
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Re: scanning and downloading at the same time

Post by Drake Ravensmith » 06 Dec 2011, 05:50

I use eye-fi cards and they do have a few issues.

- Despite the fact that they're supposed to have 'endless memory mode', they sometimes fill up. This wouldn't be a problem but I use the cards specifically so I don't have to move the cameras at all. I have found it manageable to twist the cameras along the camera mounting screw so I can release the memory card without taking the whole camera off, but I don't have a surgeon's hands and I sometime move the camera and my gooseneck extensions don't easily allow for micro-adjustments.

- Sometimes the cards send the pictures multiple times. I'll be halfway through scanning a book and stop to flex my shoulders and notice that only 25 pics have transferred on one of the cameras because it's sending each pic three times. Turning the camera on and off fixes this, but I have to remove the construction paper from the front (to block reflections) and reattach it which risk upsetting camera placement. (I may try to permanently attach this paper since I don't generally use the cameras for anything else these days.) Then there's the time wasted at the end waiting for the one card to catch up.

-This one is new and it might be related to endless memory mode again. The last time the cards filled up, I reset endless memory mode to 25%. Ever since then, I've noticed a slower download speed. I believe this may be due to the cards deleting a photo for every new pic I take. I've been waiting for the cards to fill up as an excuse to remove the cards and reset them to the previous 90% level but so far it hasn't happened yet. Since 4gb is a lot of space, I may even try getting into the habit of carefully removing and erasing the cards before each session.

When the cards were working optimally, it was possible to scan several books at a sitting and have all but the last book already transferred to the my laptop after the last page was captured. The time it takes to rename the pics for the first book and ensure that they're aren't any missing photos is usually enough to let the last pics transfer. I guess in the end it all boils down to how important it is for you not to move the cameras. A fixed camera setup would likely not be greatly benefited from using eye fi cards. My more flexible camera mounts make the eye fi a must have convenience. Even the worst delays on photo transfer are minimal when you factor in bathroom breaks. They are enormously convenient for spot checking suspect pages since the live av output of the cameras is somewhat sketchy at times. All in all I would definitely recommend them if your computer is close enough to your scanner and remind you that if you're buying used to make sure the cards have a lock tab.

Note: I have a usb hub camera trigger setup and I did try to connect the camera directly to the laptop without results. I assumed the SDM/CHDK would prevent this but it didn't hurt to try.

@Gerard

I'm not sure I understand you. You say you can't scan and download at the same time? Does that mean you're having a problems taking a pic while another is uploading?

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Gerard
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Re: scanning and downloading at the same time

Post by Gerard » 06 Dec 2011, 07:30

Drake Ravensmith wrote:...
@Gerard

I'm not sure I understand you. You say you can't scan and download at the same time? Does that mean you're having a problems taking a pic while another is uploading?
the cam have no problem with taking images, but every time a picture is taken, only the upload is starting ~9 secends after the last image is was taken, so i would have to wait 9s after an page to have "scanning and downloading"

i was using an opensource eye fi server http://code.google.com/p/eyefiserver/

which firmware do you use and how long does it take start the upload after the image was writen down to sd-card?

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Drake Ravensmith
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Re: scanning and downloading at the same time

Post by Drake Ravensmith » 06 Dec 2011, 09:38

I don't have the firmware number handy but I just updated to the most recent one a few weeks ago. I'm still not quite sure what issue you're having. When I scan, I can take the pics as fast as I can scan and they will continuously transfer to my laptop. The pics usually begin transferring between 5 and 10 seconds after they're first taken. The transfer takes up to five seconds. During optimal scanning conditions, the pics continuously transfer taking roughly 5-8 seconds per pic. By the time I finish a 250 page book about two thirds or better of the pics have transferred.

Incidentally, I use Connectify to create a wifi hotspot on my laptop so I don't need a router.

dtic
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Re: scanning and downloading at the same time

Post by dtic » 06 Dec 2011, 14:10

Gerard: Do you know if CHDK+PTP-extension can work with two cameras at the same time (connected to one computer)?

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Gerard
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Re: scanning and downloading at the same time

Post by Gerard » 06 Dec 2011, 19:45

Drake Ravensmith wrote:I'm still not quite sure what issue you're having.
my setup is two X2 cards connected to a router, on my ubuntu laptop i running an eye-fi server

the cards sending the images direct to my laptop,

the normal case is that the eye-fi cards uploading the images to the eye-fi server cloud and form there back to your laptop or to an other destiantion

my aim was to have a live preview, so i've decide that uploading to the eye-fi cloud and downloading it back is not what i wont
also i want something that is working without internet and not depend on the eye-fi servers

that is why i choose to run an opensource eye-fi server on my linux laptop, the problem with this setup is that, the eye-fi sd card waits after an image is taken (in my case ~9s), but i shoot every 3-4 s an new image, so while i'm scanning at full speed, the eye does not start to transfer

the transfer only starts at the end or while long breaks

maybe i have to investigate more in this direction, but for now the eye-fi was a disablement
dtic wrote:Gerard: Do you know if CHDK+PTP-extension can work with two cameras at the same time (connected to one computer)?
yes it works,

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Drake Ravensmith
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Re: scanning and downloading at the same time

Post by Drake Ravensmith » 06 Dec 2011, 21:10

That is rather curious. Have you seen my build thread?


www.diybookscanner.org/forum/viewtopic.php?f=1&t=1028

Basically, my cards sends the pics directly to my laptop and then photolive will put up the last pic taken in a folder. It's by no means anything approaching a perfect system but set up carefully it would allow a person to preview some of the images as they are scanning. I only tried the setup for one scanning sessions since I only scan text only books but it didn't stray too far behind. I'm still convinced that the endless memory mode is killing my transfer speed so the next time I scan I'll reset it and report back what happens.

dtic
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Re: scanning and downloading at the same time

Post by dtic » 07 Dec 2011, 05:00

Gerard wrote:
dtic wrote:Gerard: Do you know if CHDK+PTP-extension can work with two cameras at the same time (connected to one computer)?
yes it works,
Can you share a snippet of code for how you send commands to each camera? I'm asking since I can't from reading up om ptpcam and so on find details on how you direct commands to a specific camera.

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Gerard
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Re: scanning and downloading at the same time

Post by Gerard » 07 Dec 2011, 06:48

this

Code: Select all

export ptpcam=$HOME/Dokumente/robo-chdk/chdk-de/tools/ptpcam/ptpcam
$ptpcam -l
givs you as output

Code: Select all

Listing devices...
bus/dev vendorID/prodID device model
001/078 0x04A9/0x31EF   Canon PowerShot A495
001/077 0x04A9/0x31EF   Canon PowerShot A495

my current script is

Code: Select all

#!/bin/bash

bus_nr=$1
dev_nr=$2

ptpstdarg="--bus=$bus_nr --dev=$dev_nr"

ptpcam=$HOME/Dokumente/robo-chdk/chdk-de/tools/ptpcam/ptpcam

#put cam in mode 1 if it is in mode 0
$ptpcam $ptpstdarg --chdk="luar get_mode()" | grep -q -E "\d*:ret:false" && $ptpcam $ptpstdarg --chdk='mode 1'
//$ptpcam $ptpstdarg --chdk="luar set_aflock(1)"


lastimghandle=$($ptpcam $ptpstdarg -L | tail -2 | head -n 1 | grep -P "0x[^:]*:\s*\d*\s*[-\d]* \d\d:\d\d\s*IMG_\d\d\d\d.JPG" | awk '{print $1}')

#shoot the image
$ptpcam $ptpstdarg --chdk="lua shoot()"

#determin the last image handle
if [ "$lastimghandle" != "" ]
then
  $ptpcam $ptpstdarg --get-file=$lastimghandle
  $ptpcam $ptpstdarg --delete-object=$lastimghandle
else
  echo NO IMAGE
fi
to call this script simultaneously in bash just use this
(./shoot.sh 001 077) & (./shoot.sh 001 078) &

it's still alpha (some race condition in it), i have to rewrite it in c++ for an university project

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Drake Ravensmith
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Re: scanning and downloading at the same time

Post by Drake Ravensmith » 07 Dec 2011, 09:26

I went ahead and scanned some books right away. The transfer speed did increase somewhat but by the time I got the last novella I was still about 250 pages per camera behind. I wasn't breaking any speed records either.

Edit: Shortly after typing this I noticed that the little light on my router was blinking. Since my cards are supposed to send directly to my laptop I can't imagine why this might be. I guess I'll have to change the passwords next time around and see what happens.
Last edited by Drake Ravensmith on 07 Dec 2011, 18:17, edited 1 time in total.

dtic
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Re: scanning and downloading at the same time

Post by dtic » 07 Dec 2011, 14:02

Thanks Gerard!

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