[aravis] Re: Aravissrc: Multi-camera Ethernet Network Performance

  • From: Charl Wentzel <charl.wentzel@xxxxxxxxxxxxxx>
  • To: aravis@xxxxxxxxxxxxx
  • Date: Fri, 17 Nov 2017 07:37:09 +0200

Hi Guys

Last year a implemented a project using 8 Basler HD cameras connected to two Netgear Prosafe Gigabit POE switches.  I had similar issues.  I could never stream continues frames from all cameras simultaneously, in fact the best I could do was one camera, even though I had only 4 cameras on each switch.

I used the Pylon libraries supplied by Basler at the time and was planning to switch to Aravis hoping to avoid these issues.  It now seems apparent that it's a networking issue rather than a software issue.  If I do this again, I'll go USB.

Regards
Charl

On 16/11/2017 19:26, Nils Hasler wrote:

Hi Ian,

how are you connecting the cameras to the PC?

In my experience achievable bandwidth depends a lot on the employed network 
equipment. Some cheap network cards cause a lot of trouble when connecting 
multiple cameras to one card.

In my experience using a 10-gigabit card combined with a PoE switch works well 
or one network card per camera. I like Adlink GIE64+ for the latter.


nils

On 16 November 2017 at 18:06 Ian McCoy<immccoy78@xxxxxxxxx>  wrote:


Hi,

I believe there is a significant performance issue with the way aravissrc
is handling the processing of Gigabit packets when there is more than one
camera streaming images simultaneously.  I think this is preventing the
cameras/network from operating well below their maximum capability.  There
have been a few posts in the past that mentioned this and it always
dismissed as as bandwidth issue. But, I don't believe that's the case.

Our team has two applications.  The first uses 6 USB BlackFly Cameras from
Point Grey for a spherical cameras system.  The cameras are configured as
follows: 1920x1200, Grey8, and at 10Hz.  We are able to use some fairly
elaborate pipelines (encoding h.264, using a compositor, outputting
compositor image on network) with hardly any issues.  Video is smooth and
video displays well when viewed locally on computer.

As a comparison, the second application uses two Blackfly Gigabit camera
from Point Grey.  The cameras are configured as follows: 1920x1200, Grey8
and at 5Hz. This application is operating well within the bandwidth
requirements for gigabit network/camera system and I'm seeing ~70+ packet
resends errors per second spread between the two cameras.  Most packet
resends are requesting more than one Ethernet packet which I think is
causing significant performance issue when how the video is encoded and
displayed locally.  I used wireshark to get the capture and confirm the
packet resends.

In both scenarios, the same processor is being used.  Also, both
applications the cameras are being simultaneously externally trigger.

I also ran some other scenarios where I reduced the image size (600x480)
kept the same frame rate.  This scenario worked great, but as I recall from
memory I saw only using a few Megabytes of bandwidth on network.

If you got any suggestions, I would appreciate it.
--
Dr. Nils Hasler
+49 174 175 66 42
www.TheCaptury.com
The Captury GmbH, Saarbruecken, Germany
Amtsgericht Saarbrücken, HRB 101327
Executive Director: Nils Hasler



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