Camera: D-Link DCS-825L
Example image 17.5 kb, 640x352 pixels, 96x96dpi, 24bit.
 |  |
Method, use the change in image filesize as a proxy for baby movement:
- Capture image using wget from local network 192.168.1.2/image/jpeg.cgi
- Crop the image using mogrify (imagemagick) to remove date and time from image.
- An artefact of the above makes night-vision jpeg images in greyscale (and keeps lighted images in colour); we'll see later that this is useful metadata.
- Repeat as often as possible (e.g. every second); although maybe it is possible to overload the camera.
- Write to file with columns: Year, Month, Day, Hour, Minute, Seconds, FileSize, Greyscale
Analysis
- The jpeg filesize varies from 0 to about 130 bytes from second to second, even with no movement.
- Baby movements gives up to 400 bytes of variation.
- Adult movement gives many hundreds or thousands of bytes of filesize changes.
- We can cut off the awake-time evening and morning data when the night-vision was off (this is presumably when an adult was in the room putting the baby to sleep and collecting the baby in the morning).
- Each morning plot (using octave) the night's movements:
- Sleep was from 9pm until 7am, with help from parents around 04:30 to 05:00 (plus baby's own movements around 10pm, midnight, 2am, 4am):
Useful link:
- D-Link forum: http://forums.dlink.com/index.php?board=427.0
