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, run the executable bin/plaincast relative to your Go workspace. Any 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. The Chrome extension doesn't yet work.

$ bin/plaincast

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.

Known issues

• So far, only DIAL is implemented, so the Chrome extension for Chromecast doesn't work yet (I suspect it uses mDNS, which is the successor of DIAL on Chromecast).

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.