PiNUT Screencast

Is a screencasting software, that discover devices on the network advertising their services, with emphasis on ease of use and low latency.
It`s designed to be a alternative to miracast using general purpose hardware like a single-board computer and be tuneable for the use case.

The initial commit is to be considered an alpha

• No sound support
• Needs testing on Windows 11
• Docked menu panel flickers sometimes when streaming

Short term roadmap

• Implement sound support
• Implement more streaming profiles

Internationalization

• English
• Swedish

Supported Os

• Windows 10 x64 1903 or later

---

Configure a device

A device needs a Bonjour/mDNS service and mediaplayer listening on the advertised port, txt-records are used to advertise supported parameters.

Example configuration using avahi /etc/avahi/services/ptpsink.service

<?xml version="1.0" standalone='no'?><!--*-nxml-*-->
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
<name replace-wildcards="yes">Store [Samsung 40"]</name>
<service>
<type>_ptpsink._tcp</type>
<port>2000</port>
<txt-record>pixel_format=yuv420p</txt-record>
<txt-record>resolution=1280X720</txt-record>
<txt-record>framerate=30</txt-record>
<txt-record>container=nut</txt-record>
<txt-record>format=h264</txt-record>
</service>
</service-group>

Param	Available	Description
name		Description of the service
port		A free port
type	_ptpsink._tcp	Point-to-Point stream over tcp, only supported protocol for now

txt-record	Default	Available	Description
pixel_format	yuv420p	yuv420p, yuv444p	FFmpeg "pix_fmt"
resolution	1920X1080		Max resolution
framerate	30		Max framerate
container	nut	nut	Stream container
format	h264	h264	Video format

Mediaplayer scripts, for documentation on hardware acceleration see your platform.
Linux

#!/bin/sh
while true; do
mpv --no-terminal --fs --ontop --cursor-autohide=always --keep-open=no  --profile=low-latency --no-cache --untimed tcp://0.0.0.0:2000?listen
done

#!/bin/sh
#Piping from ncat results in lower latency
while true; do
ncat -l -w 1 -p 2000 | ffplay -loglevel panic -nostats -flags low_delay -probesize 32 -analyzeduration 0 -autoexit -
done

Windows

@echo off
:loop
mpv.exe --no-terminal --fs --ontop --cursor-autohide=always --keep-open=no  --profile=low-latency --no-cache --untimed tcp://0.0.0.0:2000?listen
goto loop

@echo off
rem Piping from ncat results in lower latency
:loop
ncat.exe -l -w 1 -p 2000 | ffplay.exe -loglevel panic -nostats -flags low_delay -probesize 32 -analyzeduration 0 -autoexit -
goto loop

---

Complete device setup

Raspberry Pi4 Model B running Raspberry Pi OS with desktop (32-bit)

sudo nano /boot/config.txt

dtoverlay=cma,cma-size=402653184
dtoverlay=vc4-kms-v3d

sudo reboot

Install the following packages
sudo apt-get install mpv unclutter xdotool

Verify hardware acceleration is working
mpv --hwdec=v4l2m2m --hwdec-codecs=all https://jell.yfish.us/media/jellyfish-3-mbps-hd-h264.mkv

You should see the in the output:
Using hardware decoding (v4l2m2m)

Create a script for the ptpsink service
touch ~/ptpsink.sh && chmod +x ~/ptpsink.sh && nano ~/ptpsink.sh

#!/bin/bash
#Minimize our selfs
sleep 1 && xdotool search "ptpsink.sh" windowminimize
while true; do
/usr/bin/mpv --fs --ontop --keep-open=no --hwdec=v4l2m2m --hwdec-codecs=all --profile=low-latency --no-cache --untimed tcp://0.0.0.0:2000?listen
done

Create a custom autostart
In my configuration im also starting a libreoffice slideshow fullscreen, when the device recieves a stream the video will be displayed ontop of the slideshow.

nano ~/.config/lxsession/LXDE-pi/autostart

@lxpanel --profile LXDE-pi
@pcmanfm --desktop --profile LXDE-pi
@unclutter -idle 5
@xset s noblank
@xset -dpms
@xset -s off
@lxterminal -e ~/ptpsink.sh

Restart your X session

Create a service file for avahi
sudo nano /etc/avahi/services/ptpsink.service

<?xml version="1.0" standalone='no'?><!--*-nxml-*-->
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
<name replace-wildcards="yes">Livingroom [Samsung 40"]</name>
<service>
<type>_ptpsink._tcp</type>
<port>2000</port>
<txt-record>framerate=30</txt-record>
<txt-record>pixel_format=yuv420p</txt-record>
<txt-record>resolution=1920X1080</txt-record>
<txt-record>container=nut</txt-record>
<txt-record>format=h264</txt-record>
</service>
</service-group>

sudo systemctl restart avahi-daemon

The Raspberry Pi should now be disoverable by PiNUT Screencast and ready to recieve a stream.

Credits

This software uses the following libraries
Zeroconf https://github.com/novotnyllc/Zeroconf