[Elphel-support] EXIF data from .mov file + other questions

[Oleg K Dzhimiev]

Dear Bader,


> 1) Splitting a video file to individual jpegs and linking Geo information
> to each jpeg. What is the best practice for doing so? I read that recording
> a .mov then extracting the exif data is a solution but how would that be
> done - I would really love a step-by-step (I read that there is a php that
> does this, can you forward that to me?).
>

If the GPS receiver is connected to the camera - each frame will be
geotagged by default. So, if you save a .mov of .jpegs just split it.

As an alternative to php there's a program movie2dng (
http://wiki.elphel.com/index.php?title=Movie2dng) but it splits .movs and
sets the extension to .jp4. I wrote more about it in the end of the letter,
from the command line it'll look like:

> movie2dng file.mov
>

I also have a php version - I'll polish it a bit and upload somewhere.

3) I read in one of the threads about not needing to record a KML file in
> order to geotag video frames and it also because it might make the processor
> to go over capacity. What would I need to do to disable the KML file? Do I
> uncheck geotagging in the Disk writing tool? Or do I uncheck 'Save Exif
> Data' in the advanced tab?
>

With GPS attached to the camera each frame's exif header is geotagged. And,
by default, the KML file is not generated.


> 4) How do I upgrade the SD Card? Where is the slot? Do I need to actually
> take apart the case?
>
http://wiki.elphel.com/index.php?title=File:10353-10369-assy_blowup.jpeg

You'll need to unscrew the top cover only. If there's a compass inside it'll
be installed instead of the top CF card - please, careful with the compass
cable.

Some of the CF cards will not work because of not supporting DMA.
We use *SanDisk Extreme III* series - works fine.


More about movie2dng and jp4:

Instead of jpeg you could try jp4 format.  It's a kind of a raw format -
that should give better quality - http://wiki.elphel.com/index.php?title=JP4
To split it use: http://wiki.elphel.com/index.php?title=Movie2dng

PHP code (well, not really PHP) to convert jp4->dng->jpeg:

exec("movie2dng --dng image.jp4");
> exec("dcraw -q 1 -f -c image.dng | cjpeg -quality 100 > image.jpeg");
>

"-q 1 -f" - are for VNG 4 color demosaicing. Additional programs are dcraw &
cjpeg. If you use (K)Ubuntu:

> sudo apt-get install dcraw
> sudo apt-get install libjpeg-progs
>

Best regards,
Oleg
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