add gstreamer doc (#2060)

source/_components/media_player.gstreamer.markdown

@@ -0,0 +1,93 @@
+---
+layout: page
+title: "Gstreamer"
+description: "Instructions on how to integrate Gstreamer into Home Assistant."
+date: 2017-02-016 10:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+ha_category: Media Player
+featured: false
+ha_release: 0.39
+ha_iot_class: "Local Push"
+---
+
+The `gstreamer` platform allows you to play audio via a gstreamer pipeline. Practically, this means you can play audio directly on the computer running Home Assistant. It is particularly suited for playing TTS. Advanced users can specify a pipeline to transform the audio stream and/or redirect it elsewhere.
+
+## Setup
+
+To add a `gstreamer` media player to your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+media_player:
+  - platform: gstreamer
+```
+
+And then install the following system dependencies:
+
+Debian/Ubuntu/Rasbian:
+
+```bash
+sudo apt-get install python-gst-1.0 \
+    gir1.2-gstreamer-1.0 gir1.2-gst-plugins-base-1.0 \
+    gstreamer1.0-plugins-good gstreamer1.0-plugins-ugly \
+    gstreamer1.0-tools
+```
+
+Redhat/Centos/Fedora:
+
+```bash
+sudo yum install -y python-gstreamer1 gstreamer1-plugins-good \
+    gstreamer1-plugins-ugly
+```
+
+If you're running Home Assistant in a virtual environment, you'll need to symlink the system Python's `gst` module into your virtual environment:
+
+```bash
+ln -s /path/to/your/installation/of/gst /path/to/your/venv/lib/python3.4/site-packages
+``` 
+
+On a Raspberry PI, you may need to add the Home Assistant user to the `audio` group:
+
+```bash
+sudo usermod -a -G audio <ha_user>
+```
+
+## Configuration
+
+Configuration variables:
+
+- **name** (*Optional*): Name the player.
+- **pipeline** (*Optional*): `gst` pipeline description.
+
+Only the `music` media type is supported.
+
+## Example Usage
+
+### Using with TTS
+
+To play TTS on your local computer (for example, if you have speakers attached to your Raspberry PI:
+
+```yaml
+media_player:
+  - platform: gstreamer
+
+script:
+  tts:
+    sequence:
+      - service: tts.google_say # or amazon_polly, voicerss, etc
+        data:
+          entity_id: media_player.gstreamer
+          message: "example text-to-speech message"
+```
+
+### Using with Snapcast
+
+To play to a named pipe for consumption by Snapcast:
+
+```yaml
+media_player:
+  - platform: gstreamer
+    pipeline: "audioresample ! audioconvert ! audio/x-raw,rate=48000,channels=2,format=S16LE ! wavenc ! filesink location=/tmp/snapcast_gstreamer"
+```