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I'm using a Raspberry pi to monitor a self-service fridge. When the door opens, a shell script is being executed to capture pictures until the door closes again. The problem, however, is the speed of the ARM-processor. Capturing in full resolution using fswebcam takes 2-4 seconds, which is too long.

Our idea to solve this is to split the process:

  1. Capture raw images and save to memory card
  2. After the door is closed, process the raw data. This is not time-critical.

Now, my questions are:

  1. Is this possible / wise?
  2. Which program should I use?
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  • 1
    It sounds wise to me, and it must be possible since fswebcam gets its data from somewhere. I've edited your title to hone in on that issue better. Commented Oct 30, 2013 at 16:00
  • Can you share what you're done thus far? Show us details if possible. I agreee w/ Goldilocks. Commented Oct 30, 2013 at 18:05

1 Answer 1

Reset to default
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Thats what we've got so far:

#!/bin/bash tempdir=/tmp/fswebcam host="167.174.70.42" destdir=~/fsweb tformat=%Y-%m-%d_%H-%M-%S if [ ! -d "$tempdir" ]; then mkdir $tempdir fi cd $tempdir dooropentime=$(date +$tformat) for i in {1..3} do starttime=$(date +%s%N) echo -e "\n==== starting capture at" $(date +%H:%M:%S.%N) "==== (# $i)" fswebcam --device /dev/video0 --input 0 --resolution 1280x720 --timestamp "$tformat" $tformat.jpg # fswebcam --device RAW:/dev/video0 --palette NV12MB --resolution 1280x720 $tformat.jpg endtime=$(date +%s%N) echo -e "==== capture finished at" $(date +%H:%M:%S.%N) "==== (in "$((($endtime - $starttime) / 1000000))"ms)\n" done echo "packing..." tar -cjf $dooropentime.tar.bz2 *.jpg echo "copying..." scp *.tar.bz2 pi@$host:$destdir #cp *.tar.bz2 $destdir rm -r $tempdir/* echo "done!"

It's still pretty raw, but at least it's working. Capturing a frame takes approximately 3300ms on the pi.

--device RAW:/dev/video0 produces a palette incompatibility error, and the NV12MB palette (http://www.firestorm.cx/fswebcam/ "fswebcam-20060604: Added NV12MB palette type (for raw source only)") seems to be missing.

Any ideas?

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