dolanor-galaxy/srvfb

Stream a framebuffer device over HTTP

srvfb - Stream framebuffer content over HTTP

This repository contains a small webserver that can serve the contents of a linux framebuffer device as video over HTTP. The video is encoded as a series of PNGs, which are served in a multipart/x-mixed-replace stream. The primary use case is to stream a reMarkable screen to a computer and share it from there via video-conferencing or capturing it. For that reason, there is also a proxy-mode, which streams the frames as raw, uncompressed data from the remarkable and can then do the png-encoding on a more powerful machine. Whithout that, the framerate is one or two frames per second, which might not be acceptable (it might be, though).

This should be considered a tech demo in the current state. The code is not particularly clean, it's not in any way secured, probably not very efficient and it's taylored specifically to the reMarkable (e.g. it can only stream 16-bit grayscale images). Feel free to use it and report any bugs you find, but I don't make any promises in regards to support or stability and any issues not directly related to my usecase will likely be closed.

You can see a short video demonstrating this in this tweet

Installation and usage

You need a working Go installation and ssh-access to your reMarkable. You can then obtain, install and run the code via

go get -d -u github.com/Merovius/srvfb
GOARCH=arm GOOS=linux go build github.com/Merovius/srvfb
scp srvfb [email protected]:
ssh [email protected] ./srvfb -device /dev/fb0 -listen :1234

If you then open http://10.11.99.1:1234/ in your browser (only Chrome is tested) you should see the stream from your reMarkable. To use proxy-mode, run (in a separate terminal)

go build github.com/Merovius/srvfb
./srvfb -listen localhost:1234 -proxy 10.11.99.1:1234

and open http://localhost:1234/ in your browser.

Once you can see the reMarkable screen in your browser (via proxy or not), clicking on the image should rotate it by 90°.

This repository also contains systemd unit files to run srvfb automatically (using socket activation). For security reasons, it only listens on the USB network, though. To use it, run

cd $(go env GOPATH)/src/github.com/Merovius/srvfb
GOARCH=arm GOOS=linux go build github.com/Merovius/srvfb
scp srvfb [email protected]:/usr/bin
scp contrib/srvfb.service contrib/srvfb.socket [email protected]:/etc/systemd/system
ssh [email protected] systemctl enable --now srvfb.socket

License

Apart where otherwise noted, this code is published under the Apache License, Version 2.0:

Copyright 2018 Axel Wagner

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.