Plaincast

This is a small DIAL server that emulates Chromecast-like devices, and implements the YouTube app. It only renders the audio, not the video, so it is very lightweight and can run headless.

It can be used as media server, for example on the Raspberry Pi.

Installation

I'm going to assume you're running Linux for this installation guide, preferably Debian Jessie (or newer when their time comes). Debian before Jessie contains too old versions of certain packages.

First, make sure you have the needed dependencies installed:

• golang 1.3 (1.1+ might also work, but 1.0 certainly doesn't)
• libmpv-dev
• youtube-dl (see also 'notes on youtube-dl' below)

These can be installed in one go under Debian Jessie:

$ sudo apt-get install golang libmpv-dev youtube-dl

If you haven't already set up a Go workspace, create one now. Some people like to set it to their home directory, but you can also set it to a separate directory. In any case, set the environment variable $GOROOT to this path:

$ mkdir golang
$ cd golang
$ export GOPATH="`pwd`"

Then get the required packages and compile:

$ go get -u github.com/aykevl/plaincast

To run the server, you can run the executable bin/plaincast relative to your Go workspace.

$ bin/plaincast [OPTIONS]

or install it as service

$ cd src/github.com/aykevl/plaincast
$ make install

If you want to remove service $ make remove

Any browser that supports chromecast extension and Android phone with YouTube app (or possibly iPhone, but I haven't tested) on the same network should recognize the server and it should be possible to play the audio of videos on it.

Manual service installation

Copy compiled binary file plaincast to /usr/local/bin/ and create new user plaincast in group audio

$ useradd -s /bin/false -r -M plaincast -g audio

Create directory

$ mkdir -p /var/local/plaincast
$ chown plaincast:audio /var/local/plaincast

Copy systemd unit file plaincast.service to /etc/systemd/system/ and enable the service

$ systemctl enable plaincast

Options

-h, -help	    	Prints help text and exit
-ao-pcm		    	Write audio to a file, 48kHz stereo format S16
-app		    	Name of the app to run on startup, no need to use 
                	as currently is supported only YouTube	
-cachedir	    	Cache directory location for youtube-dl
-config		    	Location of the configuration file, path to to config
                	(default location ~/.config/plaincast.json)
-friendly-name  	Custom friendly name (default "Plaincast HOSTNAME")	
-http-port	    	Custom http port (default 8008)
-log-libmpv	    	Log output of libmpv
-log-mpv	    	Log MPV wrapper output
-log-player	    	Log media player messages
-log-server	    	Log HTTP and SSDP server
-log-youtube    	Log YouTube app
-loglevel	    	Baseline loglevel (info, warn, err) (default "warn")
-no-config	    	Disable reading from and writing to config file
-no-sspd	    	Disable SSDP server   

Snapcast support

You can easily write audio output to snapcast pipe using option

-ao-pcm PATH-TO-SNAPFIFO

Notes on youtube-dl

youtube-dl is often too old to be used for downloading YouTube streams. You can try to run youtube-dl -U, but it may say that it won't update because it has been installed via a package manager. To fix this, uninstall youtube-dl, and install it via pip. The steps required depend on the version of Python in your $PATH variable. Check it with:

$ python --version

Install using pip for Python 2 (usually version 2.7.x), on Debian stretch and below:

$ sudo apt-get remove youtube-dl
$ sudo apt-get install python-pip
$ sudo pip2 install youtube-dl

Install using pip3 for Python 3 (version 3.x). Only required when you have configured the python binary to point to Python 3, or maybe on newer versions of Debian.

$ sudo apt-get remove youtube-dl
$ sudo apt-get install python3-pip
$ sudo pip3 install youtube-dl

Afterwards, you can update youtube-dl using:

$ sudo pip install --upgrade youtube-dl

Or for Python 3:

$ sudo pip3 install --upgrade youtube-dl

It is advisable to run this regularly as it has to keep up with YouTube updates. Certainly first try updating youtube-dl when plaincast stops working.

Docker

Both Dockerfile and Docker Compose manifest are provided. The former builds a Docker image with the program binary built from local code and the required build dependencies. The Docker image also includes a recent youtube-dl version. This will avoid the need of installing a recent version for the local OS and version on the host, thus avoiding the risks of installing any software. The Docker Compose manifest contains the configuration settings needed to launch a Docker container. To run the Docker image, just run:

$ docker-compose up --build --force-recreate

Thanks

I would like to thank the creators of leapcast. Leapcast is a Chromecast emulator, which was essential in the process of reverse-engineering the YouTube protocol and better understanding the DIAL protocol.