Add documentation on CMSD

Author: dsilhavy

pages/usage/cmsd.md

@@ -0,0 +1,50 @@
+---
+layout: default
+title: Common Media Server Data
+parent: Usage
+---
+
+# Common Media Server Data
+
+[CTA-5006 - Common Media Server Data](https://cdn.cta.tech/cta/media/media/resources/standards/pdfs/cta-5006-final.pdf) (
+CMSD) defines a structure for data transmitted in the response to a request from a media player
+for an HTTP adaptive streaming media object. The response usually originates at an origin server
+and is then propagated through a series of intermediaries to the player.
+
+The purpose of the Common Media Server Data (CMSD) specification is to define a standard
+means by which every media server (intermediate and origin) can communicate data with each
+media object response and have it received and processed consistently by every intermediary
+and player, for the purpose of improving the efficiency and performance of distribution and
+ultimately the quality of experience enjoyed by the users.
+
+dash.js currently supports two CMSD keys, namely `etp` (estimated throughput) and `mb` (maximum suggested bitrate).
+
+## Configuration Options
+
+dash.js offers configuration options related to CMSD. The following settings can be configured:
+
+| Setting              | Description                                                                                                                                                                                                                                                                                                                                                              |
+|----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `enabled`            | Enable or disable the CMSD response headers parsing.                                                                                                                                                                                                                                                                                                                     | 
+| `abr.applyMb`        | Set to true if dash.js should apply the maximum suggested bitrate derived from the CMSD `mb` key in its ABR logic.                                                                                                                                                                                                                                                       | 
+| `abr.etpWeightRatio` | Sets the weight ratio (between 0 and 1) that shall be applied on the value of the CMSD `etp` key compared to the measured throughput on client side. For instance, setting this value to 0.5 will result in an equal 50% weight on the throughput value provided by the server via CMSD and 50% weight on the throughput value calculated by dash.js on the client-side. | 
+
+For a full documentation of all CMSD related options please refer to
+our [API documentation](https://cdn.dashjs.org/latest/jsdoc/module-Settings.html#~CmsdSettings).
+
+### Example configuration:
+
+````js
+player.updateSettings({
+    streaming: {
+        cmsd: {
+            enabled: true,
+            abr: {
+                applyMb: true,
+                etpWeightRatio: 0.5
+            }
+        },
+    },
+})
+````
+