[Elphel-support] Camogm triggered mode

[Andrey Filippov]

Dimitrios,

Why do you need external triggering? To reduce number of images when the
camera moves slowly?
If that is correct, I would recommend you just skip some images from
recording, keeping the sensor frame rate high. That will allow the
autoexposure to work properly.

As for the variable rate recording with camogm - it is just prevented by
the software to make players happy - currently when the camogm detects
frame period change, it closes current file and starts a new one (that test
can be easily bypassed). Actually single-frame (maybe more than one frame -
I'll need to look in the code)  drops can be tolerated - that is done to
continue recording when hi-res image snapshot is made.

While mov format we use does not support variable frame rate, with the
timestamps embedded in each frame it is not critical. Actually when
processing mov files in Eyesis we completely skip the MOV file header and
just split the remaining of the file into individual JPEG (JP4 actually as
the JPEG format does not provide quality we need) frames. That also means
that if MOV file is corrupted (camera records the MOV file header when
closing the file, so power loss during recording will result in a file with
no header) it can still be split into individual frame files.

Andrey

On Wed, Jan 11, 2012 at 1:49 AM, Dimitrios <dz at telemetry.gr> wrote:

> Polto
>
> that may well be a solution. The project I'm working on produces
> hundreds of images per hour in one go, which should be processed at the
> end of the day, but this is irrelevant since the directory tree can be
> structured according to the need.
>
> I've already successfully compiled and run some trivial applications for
> the camera, but not yet camogm, although I've done some work on parsing
> a new 'trigger' command. If MOV cannot accept irregular frame timings
> then the 'trigger' command might not be feasible.
>
> Thank you much
> Dimitrios
>
>
> On 01/07/2012 12:02 PM, Alexandre Poltorak wrote:
> > Dimitrios,
> >
> > To solve the problem with tons of files in one directory you can create
> a directory tree to reduce the number of files per folder.
> >
> > Let's say you keep videos for 4 weeks in your app on the camera's
> internal flash. You can create a directory per week, sub-directory for each
> day of week, and a sub-directory for each hour for example. You use simple
> shell or PHP script to set camogm to record to those directories.
> >
> > Adding the ability to camogm to append some video to a file may be a
> nice option for some configurations. I do not know if MOV of OGG support
> that. We also have an experimental and unsupported MKV support on a fork of
> camogm. The downside is if a file-corruption occurs, you loose much more.
> >
> > This wiki page describe how to setup your SDK on Ubuntu/Kubuntu:
> > http://wiki.elphel.com/index.php?title=Elphel_Software_Kit_for_Ubuntu
> >
> > Or you can download the Kubuntu ISO here:
> > http://community.elphel.com/files/live-dvd/
> >
> > Regards,
> > Polto
> >
>
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