pychromecast

Library for Python 3.6+ to communicate with the Google Chromecast. It currently supports:

Auto discovering connected Chromecasts on the network
Start the default media receiver and play any online media
Control playback of current playing media
Implement Google Chromecast api v2
Communicate with apps via channels
Easily extendable to add support for unsupported namespaces
Multi-room setups with Audio cast devices

Check out Home Assistant for a ready-made solution using PyChromecast for controlling and automating your Chromecast or Cast-enabled device like Google Home.

Dependencies

PyChromecast depends on the Python packages requests, protobuf and zeroconf. Make sure you have these dependencies installed using pip install -r requirements.txt

How to use

>> import time
>> import pychromecast

>> chromecasts = pychromecast.get_chromecasts()
>> [cc.device.friendly_name for cc in chromecasts]
['Dev', 'Living Room', 'Den', 'Bedroom']

>> cast = next(cc for cc in chromecasts if cc.device.friendly_name == "Living Room")
>> # Start worker thread and wait for cast device to be ready
>> cast.wait()
>> print(cast.device)
DeviceStatus(friendly_name='Living Room', model_name='Chromecast', manufacturer='Google Inc.', uuid=UUID('df6944da-f016-4cb8-97d0-3da2ccaa380b'), cast_type='cast')

>> print(cast.status)
CastStatus(is_active_input=True, is_stand_by=False, volume_level=1.0, volume_muted=False, app_id='CC1AD845', display_name='Default Media Receiver', namespaces=['urn:x-cast:com.google.cast.player.message', 'urn:x-cast:com.google.cast.media'], session_id='CCA39713-9A4F-34A6-A8BF-5D97BE7ECA5C', transport_id='web-9', status_text='')

>> mc = cast.media_controller
>> mc.play_media('http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4', 'video/mp4')
>> mc.block_until_active()
>> print(mc.status)
MediaStatus(current_time=42.458322, content_id='http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4', content_type='video/mp4', duration=596.474195, stream_type='BUFFERED', idle_reason=None, media_session_id=1, playback_rate=1, player_state='PLAYING', supported_media_commands=15, volume_level=1, volume_muted=False)

>> mc.pause()
>> time.sleep(5)
>> mc.play()

Adding support for extra namespaces

Each app that runs on the Chromecast supports namespaces. They specify a JSON-based mini-protocol. This is used to communicate between the Chromecast and your phone/browser and now Python.

Support for extra namespaces is added by using controllers. To add your own namespace to a current chromecast instance you will first have to define your controller. Example of a minimal controller:

from pychromecast.controllers import BaseController

class MyController(BaseController):
    def __init__(self):
        super(MyController, self).__init__(
            "urn:x-cast:my.super.awesome.namespace")

    def receive_message(self, message, data):
        print("Wow, I received this message: {}".format(data))

        return True  # indicate you handled this message

    def request_beer(self):
        self.send_message({'request': 'beer'})

After you have defined your controller you will have to add an instance to a Chromecast object: cast.register_handler(MyController()). When a message is received with your namespace it will be routed to your controller.

For more options see the BaseController. For an example of a fully implemented controller see the MediaController.

Exploring existing namespaces

So you've got PyChromecast running and decided it is time to add support to your favorite app. No worries, the following instructions will have you covered in exploring the possibilities.

The following instructions require the use of the Google Chrome browser and the Google Cast plugin.

In Chrome, go to chrome://net-internals/#capture

Enable the checkbox 'Include the actual bytes sent/received.'

Open a new tab, browse to your favorite application on the web that has Chromecast support and start casting.

Go back to the tab that is capturing events and click on stop.

From the dropdown click on events. This will show you a table with events that happened while you were recording.

In the filter box enter the text Tr@n$p0rt. This should give one SOCKET connection as result: the connection with your Chromecast.

Go through the results and collect the JSON that is exchanged.

Now write a controller that is able to mimic this behavior :-)

Ignoring CEC Data

The Chromecast typically reports whether it is the active input on the device to which it is connected. This value is stored inside a cast object in the following property.

cast.status.is_active_input

Some Chromecast users have reported CEC incompatibilities with their media center devices. These incompatibilities may sometimes cause this active input value to be reported improperly.

This active input value is typically used to determine if the Chromecast is idle. PyChromecast is capable of ignoring the active input value when determining if the Chromecast is idle in the instance that the Chromecast is returning erroneous values. To ignore this CEC detection data in PyChromecast, append a Linux style wildcard formatted string to the IGNORE_CEC list in PyChromecast like in the example below.

pychromecast.IGNORE_CEC.append('*')  # Ignore CEC on all devices
pychromecast.IGNORE_CEC.append('Living Room')  # Ignore CEC on Chromecasts named Living Room

Thanks

I would like to thank Fred Clift for laying the socket client ground work. Without him it would not have been possible!