reStream

reMarkable screen sharing over SSH.

Installation

Unix

1. Install lz4 on your host with your usual package manager. On Ubuntu, apt install liblz4-tool will do the trick.

2. Set up an SSH key and add it to the ssh-agent, then add your key to the reMarkable with ssh-copy-id root@10.11.99.1. Note: the reMarkable 2 doesn't support ed25519 keys, those users should generate and rsa key. Try out ssh root@10.11.99.1, it should not prompt for a password.

3. Clone this repository: git clone https://github.com/rien/reStream.

4. Copy the restream executable to the reMarkable and make it executable.

   # scp restream.arm.static root@10.11.99.1:/home/root/restream
   # ssh root@10.11.99.1 'chmod +x /home/root/restream'
   

   --or--

   Install via toltec if you use it.

   # ssh root@10.11.99.1 'opkg install restream'
   

Windows

1. Install git for windows, which includes Git BASH.
2. Install ffmpeg for windows.
3. Download lz4 for windows and extract the zip to a folder where you'll remember it (e.g. C:\Users\{username}\lz4).
4. Add the ffmpeg and lz4 directories to the windows Path environment. Here is a quick guide how.
   • Control Panel > Edit the system environment variables > Environment Variables
   • Find the Path variable under System variables, click edit.
   • Add two New entries: one to the bin directory in the ffmpeg directory, and one to the lz4 directory you created.
   • Click OK
5. (Re)start bash so the new Path is used.
6. Generate a new ssh key using ssh-keygen.
7. Send the public key to the reMarkable (connect trough USB cable) using ssh-copy-id -i ~/.ssh/id_rsa root@10.11.99.1
8. Try out ssh root@10.11.99.1, it should not prompt for a password.
9. Go to step 3 of the Unix installation instructions.

Usage

1. Connect your reMarkable with the USB cable.
2. Make sure you can open an SSH connection.
3. Run ./reStream.sh
4. A screen will pop-up on your local machine, with a live view of your reMarkable!

Options

• -h --help: show usage information
• -p --portrait: shows the reMarkable screen in portrait mode (default: landscape mode, 90 degrees rotated tot the right)
• -s --source: the ssh destination of the reMarkable (default: root@10.11.99.1)
• -o --output: path of the output where the video should be recorded, as understood by ffmpeg; if this is -, the video is displayed in a new window and not recorded anywhere (default: -)
• -f --format: when recording to an output, this option is used to force the encoding format; if this is -, ffmpeg’s auto format detection based on the file extension is used (default: -).
• -w --webcam: record to a video4linux2 web cam device. By default the first found web cam is taken, this can be overwritten with -o. The video is scaled to 1280x720 to ensure compatibility with MS Teams, Skype for business and other programs which need this specific format. See video4linux loopback for installation instructions.
• -m --measure: use pv to measure how much data throughput you have (good to experiment with parameters to speed up the pipeline)
• -t --title: set a custom window title for the video stream. The default title is "reStream". This option is disabled when using -o --output

If you have problems, don't hesitate to open an issue or send me an email.

Requirements

On your host machine:

• Any POSIX-shell (e.g. bash)
• ffmpeg (with ffplay)
• ssh
• Video4Linux loopback kernel module if you want to use --webcam

On your reMarkable you need the restream binary (see installation instructions).

Video4Linux Loopback

To set your remarkable as a webcam we need to be able to fake one. This is where the Video4Linux loopback kernel module comes into play. We need both the dkms and util packages. On Ubuntu you need to install:

apt install v4l2loopback-utils v4l2loopback-dkms

In some package managers v4l2loopback-utils is found in v4l-utils.

After installing the module you must enable it with

modprobe v4l2loopback

To verify that this worked, execute:

v4l2-ctl --list-devices

The result should contain a line with "platform:v4l2loopback".

Troubleshooting

Steps you can try if the script isn't working:

• Set up an SSH key
• Update ffmpeg to version 4.

Development

If you want to play with the restream code, you will have to install Rust and setup the reMarkable toolchain to do cross-platform development.