Video delay

Lex

Hi,
My video feed has a delay about 1 second, which is extremly long when testing in a local network.
The setup I have:
Rover, PRI4B 8GB, Navio2, zerotier vpn, GO Pro camera with CSI-2 to HDMI bridge, ethernet connection to both RPI and GCS (static testing on the table); Ubuntu 20.04 laptop with QGC. Video 640-480/15 fps/udp.

A ping from laptop to RPi is 1.1 ms in average, thus video takes 1000 times longer... I tried to change video resolution from 1080p down to 480, but latency stays the same.
Is there any configuration options in UAVMAtrix to reduce video latency, like buffering video on RPI?

∕Lex

Sinamics

Lex Hi Lex.
I agree, 1sec is way to long. Have you tried to only use picamera or usb cam to exlude the CSI bridge adapter?
There is no option in UAVcast to add buffering, im pretty sure adding any buffering will increase the delay, but you can offourse add a custom gstreamer pipeline and add elements manually.

You can also try TCP, see if that makes any changes.

Lex

Hi,
I spent some time reading through several forums and found a few references where udp problem with NAT was mentioned. I actually have at least 2 nats in a row...
Another thing I found was a reference to rtpjitterbuffer, which adds additional latency, however I have no idea how much. I will try tcp and other changes on Tuesday in a location with a good coverage and DL∕UL to see the difference. I will also try to use both rover and GCS over cellular link.

one more question on a side - while changing from mavproxy setup to UAVMatrix I lost a possibility to move rover backwards (negative throttle) even if I have joystick center as a zero throttle (manual mode). It is the same in both MP and QGC. Did I miss some settings or is it a limitation in your sw?

Sinamics

Hi Lex

I spent some time reading through several forums and found a few references where udp problem with NAT was mentioned. I actually have at least 2 nats in a row...

its very common to have nested NAT in a LTE network, this is one of the reason rtpjitterbuffer was added to the pipeline due to grey overlay, pixelating images. However, the lateancy would not change significantly.

Lex one more question on a side - while changing from mavproxy setup to UAVMatrix I lost a possibility to move rover backwards (negative throttle) even if I have joystick center as a zero throttle (manual mode). It is the same in both MP and QGC. Did I miss some settings or is it a limitation in your sw?

No, there is no limitation in UAVcast. You should have the same features as using standard 433 radio transmitter.
Did you calibrate your radio properly in Mission Planner Joystick page?

Lex

Do I need to "calibrate radio" if I use cellular modem?
I tried to follow guide on https://ardupilot.org/rover/docs/rover-motor-and-servo-configuration.html
However I can't get wheels to turn backwards. Setting negative value "Test Motor B" turns servo in the opposite direction , but in "Test Motor A" negative value has no effect.
Do you have any hints or links to a proper setup pages? Also parameter list states that min/mas throttle are for auto mode, but I plan to use manual one..

Lex

managed to get thr to work. i have to set servo min to 800 which below recommended 1000...

Sinamics

Lex managed to get thr to work. i have to set servo min to 800 which below recommended 1000..

glad you got it working and thank you for the information.

Lex

To conclude, it works well with 1280x720, fps 15, bitrate 2M on 5G cellular connection. GSC: QGC + video separately with gstreamer. Full HD does not work due to Raspberry Pi cpu load, so even telemetry periodically got lost.