Experimental Physics and
Industrial Control System

Steve Shoaf <[email protected]> · Wed, 10 Oct 2007 15:13:27 -0500

Emmanuel,
On Oct 10, 2007, at 1:42 PM, Emmanuel Mayssat wrote:

Hello all,
I tried frame grabber, etc. recently decided to move to an AXIS video

server. The asyn/epics driver is in development. We are reading the

mjpeg video stream (using the GPL code from axmjpeg). The
throughput of

the video stream on the network can be throttled on the server
side. We

use interrupt to trigger frame processing.
We completed performance testing. We can achieve the 30 frames per

second benchmark. I was shocked with the achieved performance. This

solution rocks! I gave myself a pat on the back just for thinking
of it!

Load on cpu < 5%, load on local area network... negligible.
What takes time is the processing of each frame (background
subtraction,

ROI, intensity monitor, etc.), so this part needs to be optimized.
This

is actively being developed/reviewed.

We had a similar situation at the APS when we were upgrading our
analog based frame grabber system. The amount of time to perform
simple operations was adding up, and we wanted the system to perform
all of the analysis operations in real time. I started using vector
processing on the image data and saw substantial speed improvements.
For instance, the background subtraction on an 8-bit grayscale vga
size image took ~4ms using a simple for-next loop. The vector based
subtraction completes in under 1 ms. I presented a poster on this at
PAC over the summer and can email you a copy of the paper if you want.
Steve
--
Emmanuel
Here at the CLS we're using linux-based soft IOCs to
communicate with Flea and Flea2 cameras.
We're having difficulty in achieving video frame rates
greater than about 10 Hz at 640x480 resolution. I'm
interested to know how you are getting such fine performance
(aside from using RTEMS :-)

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System