[Elphel-support] Camogm triggered mode

[Dimitrios]

Hi Alexander and thank you for the suggestions.
I hope I'm not wasting the list's bandwidth with a flood of questions.

I see that the Arduino code uses

   wget http://127.0.0.1/snapfull.php

I am already using imgsrv very satisfactorily for storing the images
outside the camera (a 90 degree Hammer). I was looking for ways to store
the images to the internal 2x16GB CF cards so that the whole process be
contained within the camera.

The triggered mode sounds interesting, but if the camera is unresponsive
while waiting, then that does not fit the purpose.

I was thinking of modifying camogm to do what you describe for triggered
mode. Here is a small description of it (rather ambiguous):

----------------------------------------------------------
Desired functionality and draft camogm API extension:

a. Triggered image/burst/stream recording to disk.
b. User defined filename or tag of the stored image. If the frame is
stored in a container then the tag could be set in the EXIF data for
that frame.

This allows an external application/signal to save a frame/burst of
frames to disk on demand rather than continuously, either in an Ogg or
Mov container or as individual files. Communication with camogm is
through camogm's input pipe.

The user will have a new 'trigger' camogm command with the following
options:

1.	Trigger single snapshot write to disk, with optional user filename or
tag:

	echo "trigger name=<filename or tag>" > /path/to/input_pipe
	
2.	Trigger burst snapshot write to disk, with optional user filename or
tag and size of burst [default 5]:

	echo "trigger name=<filename or tag> burst=5"
	
	Filenames or tags for each image in the burst are created by appending
an auto-incrementing integer to the filename/tag given by the user, or
the default filename created by camogm
	
3. Trigger duration limited recording to disk, with optional user
filename or tag:

	echo "trigger name=<filename or tag> duration=5.32"
	
	Filenames or tags for each image are created by appending an
auto-incrementing integer to the filename/tag given by the user, or the
default filename created by camogm.

-----

So, I was thinking of parsing the new command and then patch camogm at
some place where it's waiting for the next frame to come but prevent it
from saving unless a trigger is seen in the input pipe. After that, it
goes again into waiting for a trigger. The process starts and ends as
usual with the start/stop camogm commands.

The good thing with open source software is that you can scratch your
own itch. The difficulty is knowing where to start, and the learning
curve here is steep, so any suggestions are very welcome  :-)

Best regards
Dimitrios


On 01/05/2012 07:10 PM, Alexandre Poltorak wrote:
> Hi Dimitrios,
> 
> Please take a look on http://wiki.elphel.com/index.php?title=Arduino
> 
> This method have a big latency for executing the command. You can use 
> http://wiki.elphel.com/index.php?title=Circbuf and 
> http://wiki.elphel.com/index.php?title=Imgsrv to get precisely the image
> that was acquired during the trigger.
> 
> Also in triggered / slave mode the camera will record frames on external 
> trigger to the internal HDD using camogm. You will get MOV files with
> triggered frames. The problem of this method is that between triggers
> the camera is completely unresponsive. (so you can not even do a
> network preview or telnet)
> 
> Another idea is to record every single frames using camogm and only mark
> images on trigger inside EXIF for later processing.
> 
> Best regards.
> Polto