Pi-assisted streaming

Use one of your many spare Raspberry Pis as a remote camera or go crazy and run everything from a Raspberry Pi 4.

While we were planning this feature, a little voice at the back of our head muttered, “Can we get a Raspberry Pi angle in?”. It turned out that voice was actually that of our group editor (that’s Group Editor in Chief, Tech to you – Ed), and we like to keep him happy. So we’ve come up with a couple of ways to quieten his screams for Raspberry Pi streams.

We’re always looking for new Pi camera projects, so first we reached for our trusty Pi Zero and attached the camera that we used for our motion detection tutorial back in LXF266. Remember that if you’re setting up a headless Pi from scratch, the SSH service is disabled by default. If you’re running wirelessly you’ll need to tell it about that too. This you can do by putting an empty file named ssh and another file full of wireless network info (wpa_supplicant.conf) on the boot partition of your Pi’s SD Card. Then you’ll need to run raspi-config on it to enable the camera in the Interfaces section. Again, a quick search engine query will help you if you get stuck.

The raspistill and raspivid programs which ship with the Pi are commonly used to test that camera-related things are working. But it turns out you can use raspivid to make your Pi into a rough ‘n’ ready network source in OBS. Just SSH into it and run:

$ raspivid -t 0 -l -n -w 640 -h 360 -o tcp://:3333 replacing with that of your Pi. There are a thousand and one options for the program, and the ones we use tell it (in order) to keep streaming forever, listen on a TCP socket, not display a preview (although that would be tricky without a monitor) and serve a 640x360 stream on port 3333 the interface specified.

You can specify all interfaces with tcp://0.0.0.0:3333, and it’s also possible to stream over UDP, too. In order to use this in OBS, add a Media Source, uncheck the local file box and use the same tcp://:3333 URL that you used in the command above in the input box. Once you’ve added the source it’ll initially be blank for a few seconds, and then you should see the video stream. If you’re like us and using a Pi Zero (or even an OG Pi from nine years ago), this delay will be significant because the Pi’s SoC has to do some work encoding the stream to h.264. This effect is compounded over wireless, so if you were hoping to perform some kind of multi-camera choreographed line-dancing routine this

probably isn’t the best solution. But it can make for some pretty amusing and occasionally paradoxical multi-room antics.

Next, we approached the Raspberry Pi Foundation which kindly sent us an 8GB Raspberry Pi 4, a High Quality Pi Camera and a 6mm lens. There’s another official lens (and a whole bunch of unofficial ones): the telephoto model, which is slightly pricier, but also less suited for streaming unless you are shooting distant objects. It’s easy enough to set all this up (though Mike Bedford managed to get fourpages out of it on page 48) but if you’re using the 6mm lens then remember to remove the CS-mount adapter that comes attached to the

HQ camera module, otherwise you’ll never be able to get it in focus.

Stay focused

This lens has two manual adjustment rings – focus and aperture – which lock closed with the helpfully provided screwdriver. If you’re not used to manual lenses, it can be tricky to get the hang of, but you can set up raspivid exactly as we did earlier and see if you’re going in the right direction. Our advice is to start by pointing the camera where you want to film, then adjust the aperture ring until it looks like enough light is getting in (make sure there’s enough light, too; it’s not a night vision camera). Then screw the aperture ring to fix it in place and adjust the focus until it’s crystal clear.

Speaking of focus, remember that it’s possible to adjust the focus on the standard Pi camera, too. On older models you need to be a bit brave scraping off the glue around the lens, but then you’ll find it rotates quite freely. Then you can get it focused right up close for a macrovision stream of your bird box. Pimoroni sells a handy lens adjustment tool for this, as well as all kinds of lenses for both camera models.

To finish we thought we’d do something a little adventurous. After all, we had one of the most powerful Raspberry Pis in the known universe in our possession. There’s no official build of OBS for the Pi, but it’s open source so we figured let’s just have a go at compiling it ourselves. You might be able to do this on a Pi 3 as well, but you’ll need a swap file because 1GB of RAM isn’t going to cut it. And it’ll take a very long time. There’s a thread all about this on the OBS forums at https:// obsproject.com/forum/threads/obs-raspberry-pi-buildinstructions.115739, so check there if you run into any difficulties. Things tend to break often, because updates in both Raspberry Pi OS and the OBS source code itself stop the two playing nicely together.

An awful lot of packages need to be installed before we can begin, and it wouldn’t be terribly useful (for our paper readers who can’t copy and paste) to list them here. Instead we’ll use Xavier Alonso’s rather excellent script which you can find at https://github.com/ xbelanch/OBS4Pi. You’ll need to upgrade to the not-yet released Bullseye edition of the Pi OS to start. To do this edit /etc/sources.list and change all references of buster to bullseye . Then do the ol’ update, upgrade apt-dance and reboot. Welcome to the future. Now download the build.sh file from the GitHub, make it executable, and run it with

$ wget https://github.com/xbelanch/OBS4Pi/raw/ main/build.sh

$ chmod 755 build.sh

$ ./build.sh

Your Pi will take an awfully long time to do this, and might get fairly hot. Besides OBS, the script compiles custom versions of FFMPEG (SRT transport support isn’t included in the regular version) and all the associated codecs. If it completes without error, you should be able to start OBS from the command line. We didn’t download the launcher from Xavier’s GitHub, so the instructions to use it won’t work. Try running the obs command directly, though – you’ll see an error about invalid OpenGL contexts, because OBS isn’t familiar with the Pi’s video capabilities. To get around this, force the OpenGL version to something respectable with $ MESA_GL_VERSION_OVERRIDE=3.3 obs or indeed download Xavier’s launcher.

And there you have it – streaming from a credit card sized computer. Why not see if you can get it working with a microphone HAT. Or a thermal camera. Oh, and big thanks to Alex Blake and The Raspberry Pi Foundation for sending us all that loot. If we become a famous influencer streamer-type we’ll be sure to give you some exposure.

THINKING BIG WHILE GOING SMALL “There’s no official build of OBS Studio for the Raspberry Pi, but it’s open source so we figured let’s just have a go at compiling it ourselves”

The HQ Camera has a standard tripod mount. Handy because clumsy cabling will easily topple whatever else you balance it with.

Media Sources has all kinds of options. We couldn’t get the hardware acceleration box to work, though.