Minimalist unixy screensharing and general video streaming over RTMP

Setup

• Forward port 1935 (TCP+UDP)
• Install nginx-rtmp-module
• Add this to the very top of your /etc/nginx/nginx.conf:

					
						load_module /usr/lib/nginx/modules/ngx_rtmp_module.so;

						rtmp {
							server {
								listen 1935; # RTMP port
								chunk_size 4096;

								application live {
									live on;
									record off;
								}
							}
						}
					
				

• Alternatively you can put include rtmp.conf; into your nginx.conf and throw the rtmp {... block into /etc/nginx/rtmp.conf
• Run nginx -t to ensure that nginx still works fine.
• If nginx complains about a missing logs directory, run mkdir -p /etc/nginx/logs, this is exlusively for rtmp logs.
• Restart/reload nginx (e.g. systemctl restart nginx) after making sure that everything is fine.


• Now you can push a raw rtmp stream to rtmp://your.server/live/streamname, substitute streamname with whatever you want.
This works with obs, ffmpeg, etc...

• Here is an example for screensharing with ffmpeg:
ffmpeg -re -f pulse -ac 2 -i pulse -f x11grab -i :0.0 -vcodec libx264 -pix_fmt yuv420p -preset ultrafast -crf 20 -threads 1 -c:a aac -ar 44100 -ac 2 -f flv rtmp://your.server/live/streamname
This also works for any other video/audio stream of course, if you already have a h264/aac stream you don't have to reencode it.

• Here is another example for taking a h264+opus mkv file, copying the video stream, and reencoding the audio stream to AAC while looping forever:
ffmpeg -stream_loop -1 -re -i video.mkv -c:v copy -c:a aac -ar 44100 -ac 2 -f flv rtmp://your.server/live/streamname


• To play it back, you can use any video player that supports rtmp, h264, aac, and flv. (e.g. mpv)
rtmpdump -r "rtmp://your.server:1935/live/streamname" | mpv -
(You probably don't have to specify port 1935 manually unless you use a custom one, but it might be a good idea to do that anyway.)

I can easily stream and watch one (or probably more) ~1000-3000kbps 1920*1080@60Hz stream(s) with very high quality, 1-3s of latency, and low CPU load.
try rtmpdump -r "rtmp://cia.govt.hu:1935/live/jews" | mpv -!



BONUS: Making it work over I2P

(This assumes that you are using i2pd, adjust this accordingly if you use another router implementation.)
Since I2P can handle pretty much anything over TCP or UDP, setting it up over I2P isn't hard either.

• On your server, append this to /etc/i2pd/tunnels.conf:

				
					[rtmp-server]
					type = server
					host = 127.0.0.1
					port = 1935
					inport = 1934
					keys = rtmp-server.dat
				
			

• And restart i2pd.
(port and inport should be different because using the same port locally and for network I/O from and to I2P can lead to issues, especially if you are using 1 b32 address for multiple things at once. Other than that it's probably a very bad idea to just use port 1935 for everything.)
• If you already have another tunnel (e.g. for a web page) you can specify the same .dat keys for rtmp and use the same tunnel/address, but keep in mind that you have to manually specify destinationport = 1934 on your client later.
• If you want to use separate keys and a separate b32 address for rtmp, get your base32 address either by opening 127.0.0.1:7070 (or whatever port you configured for the web console) in lynx/links/elinks/etc, or by running curl on it and copypasting the *.b32.i2p link:
curl "http://127.0.0.1:7070/?page=i2p_tunnels" | grep rtmp-server
It will return something like this:
<div class="listitem"><a href="/?page=local_destination&b32=ao454mwqxhvoy4albtghb57ahbtzz6vo4iq7kbf3kj2x5ickcpdq">rtmp-server</a> &#8658; ao454mwqxhvoy4albtghb57ahbtzz6vo4iq7kbf3kj2x5ickcpdq.b32.i2p:1934</a></div>


• On your client(s), append this to /etc/i2pd/tunnels.conf:

				
					[rtmp-client]
					type = client
					address = 127.0.0.1
					port = 1933
					destination = ao454mwqxhvoy4albtghb57ahbtzz6vo4iq7kbf3kj2x5ickcpdq.b32.i2p
					destinationport = 1934
					keys = rtmp-client.dat
				
			

• Adjust the b32 link accordingly, and note that the port on the client is 1933 instead of 1934, you can choose any port you like.
• Restart i2pd on your client too, and now you should be able to rtmpdump -r "rtmp://127.0.0.1:1934/live/streamname" | mpv -.
• Of course you could run all of this on localhost instead if you don't have a dedicated server.