Raspberry PI Camera an alternative to GoPro etc?

[atomiclama]

Nice one James seams like you are getting there. 

My adventures stalled a bit when my laptop HDD gave up. Back up and running now with Ubuntu on a SSD why I didn';t this years ago I don';t know.

Not got my multi going yet so tests limited to walking round the garden with my laptop with the Pi sat on chair.

So far so good got about 50m with a crappy USB dongle on the Pi before the signal dropped out this was running at 720p 30fps and looked good. 1 step closer to HD FPV  ;D

[atomiclama]

Started looking at getting telemetry back from the quad.

found this https://github.com/arcoslab/python-multiwii bit old but at least gives me something to start with, not having to write all the code is a benefit.

plan is to get pi/python talking to the naze32/cleanflight and then send a UDP packet back with all the info in. So far have the pi hooked up to the naze32 been using minicom to test out the serial. so far so good.

[gowen]

So far so good got about 50m with a crappy USB dongle on the Pi before the signal dropped out this was running at 720p 30fps and looked good. 1 step closer to HD FPV  ;D

Based on my latest tests latest tests, If you increase your frame rate to 48fps for 720p @ 6Mbps, you will get a 25% reduction in latency.  About 125ms

Also, are you aware of the appsrc element, that lets you insert data into a pipeline?

[atomiclama]

Also, are you aware of the appsrc element, that lets you insert data into a pipeline?

Nope and being a bit fik what use is it? sending telemetry? looks a bit complicated for that.

[gowen]

...what use is it? sending telemetry? looks a bit complicated for that.

That just about sums it up.

I';ve been having another conversation elsewhere, where the user really wants to mux the telemetry into the gstreamer pipeline, instead of running a second UDP stream.  Appsrc seems the best way to do it, but I don';t have the time to learn gstreamer programming to that extent.  The only example code I';ve found appears not to work.   I was hoping you had more experience with gstreamer than me.

Personally, I';ll stick with the RaspiFPV approach when I finally get to that point.

[atomiclama]

  my experience of GStreamer started on page 2 of this thread.

[james]

720p49 is odd but does work - for low latency, though, drop to 640x480 and you can push the framerate to 60fps. Quality isn';t actually massively different, though the aspect ratio may be suboptimal (it won';t give you an equivalent view of a 1080p encode).

Multicasting the video is working okay here, though I';ve been having various issues making it reliable using the picamera Python lib which I';m currently using to have control over metering etc. My current multicast implementation involves pushing the data frames into Python and multicasting from there. I think I';m going to try using that to set up the camera/do AWB etc, then have my Python script invoke the raspivid command with the right parameters piped into GStreamer pipeline to actually handle the encoding/multicasting.

I can';t help but think I';m still going to basically need two Pis - one for low latency FPV and one for high-quality recording. That or a Pi compute module (which can do two cameras), but that';s a lot bulkier and more expensive!

For data out of the Pi - I';m tinkering with ZeroMQ at the moment for that,  but whatever I';m using for control/telemetry needs to be reliable so there';s some implementation details to work out.

[gowen]

640x480 certainly does give a lower latency (about 86ms) in my tests,  but then you have lost the advantage over an analogue system.  My interest in the Pi is as a low cost HD system.
I need to have a look at zeroMQ.  Could be interesting.

[Paulham]

I gave all this a try tonight, i used James';s code from post 8 and it working.

Any idea if there is a android app which will display the stream? Saves lugging a laptop around.

[atomiclama]

Well that was a bit disapointing. Hooked it all up got it streaming to my laptop, turned my TX on and

stream breaks up to an unusable level.  was expecting some interference but no this much.

Bugger, not sure what to do now?

Go through the different freq for the Wifi. Switch to 5.8 for the wifi?

How you all getting on with interference? Any ideas?

[Paulham]

Yeah you';ll need to go 5.8ghz for WiFi.

Or. Get a UHF control module for your tx

[atomiclama]

So this pretty much rules out flying with others. 

Ah well live and learn.
Just leave the Pi for recording.

[james]

5GHz wifi is easy enough - the downside is higher attenuation in free space, eg less range so more power required. The UK EIRP limits for 5GHz are pretty reasonable, though.

Just need a 5G dongle for the Pi and a 5G dongle for the laptop if your one doesn';t support it (most do these days).

[gowen]

The hard part is finding a 5Ghz wifi double compatible with the Pi

[quadfather]

The hard part is finding a 5Ghz wifi double compatible with the Pi

I wonder if the Linksys AC 580 with the help of this article could be coerced to work. 

[Rustydiver]

Hummm this has got me thinking me son has a raspberry pie havnt a clue how it works could be an interesting project for him to do.

Instead of running it off the lipo battery you could get a small USB power bank and strap on.
I got him a big one for Christmas and it will run the gopro for a few days.

[gowen]

I power mine from a 3A 5V turnigy BEC that I have modded with a USB socket. More details here http://sparkyflight.wordpress.com/2014/04/22/improved-raspberry-pi-power-supply/

[james]

Dunno how others are running them but I have three UBECs on my vehicle - one in the Pixhawk power module, one for the flashing LED lights (just for noise isolation, basically), one for the Raspberry Pi. I just cut the end off a micro USB cable and soldered the UBEC to ground/hot leads, terminated the signal leads and heatshrunk the joint. The UBEC is then soldered onto the PDB incoming power pads and job';s a good';un. The power draw of the Pi is pretty tiny - we';re talking 600mA or so at 5V, so about 0.2A at 12V. The extra weight of a battery doesn';t make a lot of sense. Going in through the micro USB is a bit bulkier than direct to the GPIO but keeps the various protection circuits in play on the Pi just in case.

I';m currently using a Canon AS2400 IS as my main camera, though that';s a bit of an experiment. I';ve moved one of my Pis to the back of the quad, pointing straight down, and I';ve switched to a NoIR camera - I';m going to be trying this out for ground surveying, might flip back to the visible-light cam but just getting some data for now.