After much chasing, and testing, I have found this to be an efficient way of getting low latency high quality HD video out of an Aircraft. The latency is around 0.4 seconds at worst which would be OK for an FPV with an APM doing the hard work.
I will continue to search for methods to drop the latency down further, but this is a lot better than the 6-12 seconds I was getting on my first attempts.
Any comment (with useful instructions) would be appreciated.
For the wireless link, I am using two UBIQUITY ROCKET M 900 with Australian ACMA approved firmware, at the base station, I am using a tracking (yet to built the tracker...) 1.5 meter long X and Y polarised Yagi, and on the plane, two RF Design flexible strip antennas, placed at right angles to each other.
but how you do that bit is up to you.....
the critical bit is getting the Raspberry Pi's to chat to each other.
I have tried to make this as user friendly as possible... good luck.
Setting up IP video for Raspberry Pi 1080p video (FPV)
You will need 2 B model Raspberry Pi's and 1 Pi Camera. (Element 14, or RS components)
Preparing your Raspberry Pi for first boot…
Follow the instructions at http://www.raspberrypi.org/wp-content/uploads/2012/04/quick-start-guide-v2_1.pdf
Install the prepared SD card in the Pi and boot.
Setting up your Pi
Connect the Pi to your router with a network cable.
On Start-up it will resize the FAT partition and present you with a menu.
Set your language, and keyboard layout.
Select Raspbian… then click install.
After this has extracted (will take a while….) it will reboot into the configuration screen (again will take a while for this first boot.)
The important things to change here are
- Enable the camera
- In advance options…..
- Set the host name (camera, for the camera end, receiver, for the viewing end)
- Memory split, set the memory for the GPU to 256
- Enable SSH ( will come in handy later, as you may need to talk to the Pi in the air.....
Then finish and reboot.
First login
Username: pi
Password: raspberry
Setting up the required programs for video streaming
Install the dependencies by running the following in a terminal:
sudo apt-get install mplayer netcat
cd /opt/vc/src/hello_pi
make –C libs/ilclient
make –C libs/vgfont
cd /opt/vc/src/hello_pi/hello_video
make
cd ~
Now repeat this for the other Pi….
Streaming…
First set up the receiver….
Ensure the receiver is connected to your network and run
ifconfig
after you press enter, you can find your ip Address. Note this down.
Then run the following.
mkfifo buffer
nc -p 5001 -l > buffer | /opt/vc/src/hello_pi/hello_video/hello_video.bin buffer
the Pi will now wait for the feed.
On the Camera Pi
Ensure camera is connected to the Pi
Ensure Pi is connected to the network (you can confirm this with ifconfig)
(see instructions at http://www.raspberrypi.org/camera for how to connect the camera)
In the following command, replace the ip address with the one you just noted down.
raspivid -t 0 -fps 15 -o - | nc 192.168.1.85 5001
if all goes well you should be streaming 1080P video at 15fps with less than 0.5seconds of delay..
now add your wireless bridge between the two, and away you go J
This information has come from the Raspberry Pi foundation website, and other sources, tested and proven by myself..
Comments
Gary, thanks for your reply.
Can you briefly explain what all you did to install gstreamer on windows? The issue is, i don't have the option to install linux on my laptop at the moment (being my office-laptop)
Thanks,Saad
I've found gstreamer to be quite flakey on my pc under windows. Looking at a ground station that is linux only - linux runs apm with mono apparently - so will load up 12.04 on a nuc I have that a client didn't like. I'll let you know how it goes.
Guys,
I was using a Mac on the receiving side at home, but now i'm away from home (for the next few weeks) and only have a windows machine with me. gstreamer doesn't seem to work on my windows machine that well. Doesn't recognize many command-line arguments. If anyone got gstreamer pilelines working on windows, would you please help me with that?
Basically if i cant get it to work on my windows machine, i can't do any more experimentation for the next 5 weeks :(
Regards,
Saad
Also make sure port 5001 is not blocked otherwise it will not go thru.
Run on computer: nc -lu 5001 | mplayer -fps 31 -cache 1024 -
Run on pi: raspivid -t 999999 -o - | nc -u [insert the IP address of the client] 5001
http://www.raspberrypi.org/camera
On windows 7 I used mplayer
http://www.mplayerhq.hu/design7/dload.html
@Christiaan
Any chance you could post some additional info on the particular gstreamer package you have setup your pi;I have followed a couple tutorials to the -t, but continue to get a "rtph264 is not a valid element" message.. I've been messing with gstreamer the last couple of nights and still no luck on my PI and on windows 7!! Its killing me..
Ag awesome thank you, this is just what I wanted. I have been scouring the internet for weeks now and could not find something this descriptive.
@Christian, it seems like the direct connect of the 5v to the 3v is relatively common, and used in a couple of functional examples I found online - (1) for direct FTDI connection to Pi, and (1) for transparent serial using a 433mhz 3dr module ;-). Not sure if this has been posted before, but these photos might give you piece of mind...
A bit more info and some sample Java/RXTX code can be found here: http://eclipsesource.com/blogs/2012/10/17/serial-communication-in-j...
Here is my 3g setup:
https://www.dropbox.com/s/fek50bm02xook8f/USB-3g-setup.txt
And this is a script to keep the 3g connection going if you loose your coverage/connection
https://www.dropbox.com/s/kqepgx1hzng40in/chksakis.sh
@Christiaan,
Can you help me with the 3G setup on RPi? Any steps would be helpful for me to get there.
Thanks,
Shyam
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