[Elphel-support] Exposure priority

[dzach]

Thank you Andrey.
I'll have a look into apps/autoexposure to see how I can use it.

I already had a go with parsedit.php but I found camvc much easier to
hack/use. Here is why:

I have an application running on a web-server on a mobile PC. The camera
is connected to this PC as are a number of other peripherals (gps,
cameras, acceleration sensors). All these are controlled through a page
served by the web-server and the touchscreen of a tablet (or a phone) in
a similar to camvc way. I needed a way to control the Elphel camera
through this user interface too.

My problems with parsedit.php :
  - HTTP POST is 4 times slower than HTTP GET for sending
parameters/getting responses to/from the camera
  - The response of parsedit.php is HTML which is a pain to parse
(except if there is a way to get a fast XML or JSON response from
parsedit.php)

Camvc is very nice and detailed and can do almost everything except:
  - cannot be used with a touch screen because the controls are very small
  - does not resize the 2592x3888 px image before sending it out and the
full size is very tough on the tablet, needs to be rotated too.
  - I don't know of a way to 'program ahead' so that the response to a
GET would be the result of the parameters already applied to the camera.
I guess that's why immediately after sending a 'set' camvc sends a 'get'.

So far I've managed to get a nice 3-5 fps sequence of resized
2592x3888px ->  320x480px images on the browser of an android phone,
using imgsrv and camvc with the help of epeg, a JPEG resizing library
and I am looking for a way to avoid manual adjustment of gain. It would
be nice but it's not critical. I thought you might have implemented
something like this for the Eyesis camera.

> the autoexposure daemon (apps/autoexposure) handles both WB and
> exposure, but gains are only adjusted for WB.

Is there a reason for not adjusting gains or it just didn't occur?

I expect to get a fair range of adjustment by setting gain below 8-10
and have the camera in auto-exposure with a max-exposure below 1 msec.
Presets are another solution but require attendance of the lighting
conditions.

Regards
Dimitrios