restream/reStream.sh

#!/bin/sh

# default values for arguments
remarkable="${REMARKABLE_IP:-10.11.99.1}" # remarkable IP address
#remarkable="${REMARKABLE_IP:-10.143.0.112}" # remarkable IP address
landscape=true          # rotate 90 degrees to the right
output_path=/dev/video5 # display output through ffplay
format=-                # automatic output format
webcam=true             # not to a webcam
hflip=false             # horizontal flip webcam
window_title=reStream   # stream window title is reStream

ssh_cmd() {
    echo "[SSH]" "$@" >&2
    ssh -o ConnectTimeout=1 \
        -o PasswordAuthentication=no \
        -o PubkeyAcceptedKeyTypes=+ssh-rsa \
        -o HostKeyAlgorithms=+ssh-rsa \
        "root@$remarkable" "$@"
}

# kill reStream on remarkable at the end.
# shellcheck disable=SC2016
exit_rm() {
    ssh_cmd 'kill $(pidof restream)'
}
trap exit_rm EXIT INT HUP

# check if we are able to reach the remarkable
if ! ssh_cmd true; then
    echo "$remarkable unreachable or you have not set up an ssh key."
    echo "If you see a 'Permission denied' error, please visit"
    echo "https://github.com/rien/reStream/#installation for instructions."
    trap - EXIT
    exit 1
fi

if ssh_cmd "[ ! -f ~/restream ] && [ ! -f /opt/bin/restream ]"; then
    echo "The restream binary is not installed on your reMarkable."
    echo "Please install it using the instruction in the README:"
    echo "https://github.com/rien/reStream/#installation"
    exit 1
fi

# store extra ffmpeg arguments in $@
set --

video_filters="colorlevels=rimin=0:rimax=29/255:gimin=0:gimax=29/255:bimin=0:bimax=29/255,transpose=3"
# rotate 90 degrees if landscape=true
$landscape && video_filters="$video_filters,transpose=1"

if $webcam; then
    video_filters="$video_filters,format=pix_fmts=yuv420p"
    format="v4l2"

    # check if there is a modprobed v4l2 loopback device
    # use the first cam as default if there is no output_path already
    cam_path=$(v4l2-ctl --list-devices |
        sed -n '/^[^\s]\+platform:v4l2loopback/{n;s/\s*//g;p;q}')

    # fail if there is no such device
    if [ -e "$cam_path" ]; then
        if [ "$output_path" = "-" ]; then
            output_path="$cam_path"
        fi
    else
        echo "Could not find a video loopback device, did you"
        echo "sudo modprobe v4l2loopback"
        exit 1
    fi

fi

# set each frame presentation time to the time it is received
video_filters="$video_filters,setpts=(RTCTIME - RTCSTART) / (TB * 1000000)"

set -- "$@" -vf "${video_filters#,}"

if [ "$output_path" = - ]; then
    output_cmd=ffplay

    window_title_option="-window_title $window_title"
else
    output_cmd=ffmpeg

    if [ "$format" != - ]; then
        set -- "$@" -f "$format"
    fi

    set -- "$@" "$output_path"
fi

set -e # stop if an error occurs

# shellcheck disable=SC2089
restream_rs="PATH=\"\$PATH:/opt/bin/:.\" restream"
listen_port=16789
ssh_cmd "$restream_rs --port $listen_port --format mono" &
sleep 1 # give some time to restream.rs to start listening
receive_cmd="nc $remarkable $listen_port"

# TODO: return this from stdout
width=1872
height=1404
pixel_format="monob"

# shellcheck disable=SC2086,SC2090
$receive_cmd |
    (
        "$output_cmd" \
            -vcodec rawvideo \
            -loglevel "error" \
            -f rawvideo \
            -pixel_format "$pixel_format" \
            -video_size "$width,$height" \
            $window_title_option \
            -i - \
            "$@" \
            ;
        kill $$
    )