Video Sunglasses - Further Details


A few updates on the Video Recording Sunglasses I blogged about earlier in the week.
Me wearing the spec - photo by James Body
I stuck in an 8GB microSD card and let the glasses record indefinitely. I was curious what would happen when the size of the video went over the 4GB limit imposed by FAT32 - and what happened when the memory card ran out of space.

File Sizes

The glasses, it turns out, record in 1.1GB chunks.
Max File Size
If you really want to know the details, the videos are

1,231,771,216 bytes
1,233,678,696 bytes

Each file is 30 minutes and 1 second long. Annoyingly, there is a gap between the videos of roughly 10 seconds.

My calculations from earlier were incorrect - an 8GB card is enough to hold just shy of 4 hours of video.

Compressing

I'm hosting the video on archive.org. One of their services is to re-encode the video into a web-friendly format. What's quite stunning (to me) is the inefficiency of the MJPEG codec which the glasses use.

Movie Files Cinepack Ogg Video 512Kb MPEG4
momoPICT0001.AVI
61.7 MB

6.9 MB

6.3 MB

The change in quality is negligible - as you can see from the demo.

I wonder how much more expensive the glasses would be if they recorded in an efficient format like Ogg Video? Obviously, there would be battery life considerations - but being able to record 10 times as much video on a single memory card is a big gain.

Another demo

This is using flash, however, Archive.org also offer HTML5 video which I'll be moving to after #NaBloPoMo has finished.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.