4MBps is sufficient for sending the compressed stream, the problem is that when we were subscribing to only a few compressed image channels through our ROS nodes we found that our bandwidth flat lined at 1MBps.
When we subscribe to the raw image stream we see up to 4MBps, this initially suggested to me that the compression was too expensive and could only manage 2 images being compressed at 5Hz, except that our laptop (dual core 2GHz) was not CPU bottlenecked. So there is a bottleneck occurring somewhere else in the system. CPU is running at 60% and Wireless N is running at 1MBps.
Thanks so much for you time,
Sean AndersonOn Thu, Mar 10, 2011 at 1:03 PM, Blaise Gassend <email@example.com> wrote:
Where are you running "rostopic bw"? If you are running it off-robot,
then each additional "rostopic bw" will cause the same information to
be transferred one extra time over the network. Hence, if you are
measuring the aggregate network bandwidth, it is perfectly normal for
the bandwidth to scale linearly with the number of running rostopic bw
A message lower down in the thread says that transferring an
uncompressed video stream transfers 8MBps. This seems to indicate to
me that there is no problem sending more than 8MBps over the network.
Could you explain why you think that 4MBps is not sufficient for
sending the compressed stream, and what problems you are actually
seeing. From your report things are behaving exactly as they should.
This seems very unlikely to me, but where exactly did your colleague
> A colleague of mine noticed something about wpa_supplicant_node having a
> wireless 11b max bandwidth limiter, is this what is limiting our transfer
> rate? Does anyone know how to unlock the limit?
see this limit?
The reason this seems unlikely to me is that on the pr2
wpa_supplicant_node is not used. All wireless goes through the 610n
router in the robot, and hence the "wireless" traffic is not at all
wireless as far as the pr2 computers are concerned.
Moreover, wpa_supplicant is only concerned with setting up the
security on the wireless connection. It does not do any packet
filtering. I have definitely used it at > 100 Mbps when network
conditions are good.
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