feat: Add keySystemsMapping to drm config (shaka-project#4254)

This allows, for example, users to use com.microsoft.playready.recommendation
instead of com.microsoft.playready.

Closes shaka-project#4243

docs/tutorials/drm-config.md

@@ -75,6 +75,22 @@ player.configure({
 If the browser supports it and you configured a license server URL for it, we'll
 use it.
 
+Alternative there are a config for make a mapping of keysystem if you know that
+is broadly supported. For example, `com.microsoft.playready.recommendation`:
+
+```js
+player.configure({
+  drm: {
+    keySystemsMapping: {
+      'com.microsoft.playready': 'com.microsoft.playready.recommendation',
+    }
+  }
+});
+```
+
+With the previous configuration you will choose the `recommendation` keySystem
+when your manifest (HLS or DASH) uses PlayReady.
+
 
 #### Clear Key
 

externs/shaka/player.js

@@ -623,7 +623,8 @@ shaka.extern.AdvancedDrmConfiguration;
  *         undefined),
  *   logLicenseExchange: boolean,
  *   updateExpirationTime: number,
- *   preferredKeySystems: !Array.<string>
+ *   preferredKeySystems: !Array.<string>,
+ *   keySystemsMapping: !Object.<string, string>
  * }}
  *
  * @property {shaka.extern.RetryParameters} retryParameters
@@ -664,6 +665,8 @@ shaka.extern.AdvancedDrmConfiguration;
  * @property {!Array.<string>} preferredKeySystems
  *   <i>Defaults to an empty array. </i> <br>
  *   Specifies the priorties of available DRM key systems.
+ * @property {Object.<string, string>} keySystemsMapping
+ *   A map of key system name to key system name.
  *
  * @exportDoc
  */

lib/media/drm_engine.js

@@ -355,7 +355,8 @@ shaka.media.DrmEngine = class {
         shaka.media.DrmEngine.fillInDrmInfoDefaults_(
             info,
             shaka.util.MapUtils.asMap(this.config_.servers),
-            shaka.util.MapUtils.asMap(this.config_.advanced || {}));
+            shaka.util.MapUtils.asMap(this.config_.advanced || {}),
+            this.config_.keySystemsMapping);
       }
     }
 
@@ -2224,16 +2225,20 @@ shaka.media.DrmEngine = class {
    * that the parser left blank. Before working with any drmInfo, it should be
    * passed through here as it is uncommon for drmInfo to be complete when
    * fetched from a manifest because most manifest formats do not have the
-   * required information.
+   * required information. Also applies the key systems mapping.
    *
    * @param {shaka.extern.DrmInfo} drmInfo
    * @param {!Map.<string, string>} servers
    * @param {!Map.<string, shaka.extern.AdvancedDrmConfiguration>}
    *   advancedConfigs
+   * @param {!Object.<string, string>} keySystemsMapping
    * @private
    */
-  static fillInDrmInfoDefaults_(drmInfo, servers, advancedConfigs) {
-    if (!drmInfo.keySystem) {
+  static fillInDrmInfoDefaults_(drmInfo, servers, advancedConfigs,
+      keySystemsMapping) {
+    const originalKeySystem = drmInfo.keySystem;
+
+    if (!originalKeySystem) {
       // This is a placeholder from the manifest parser for an unrecognized key
       // system.  Skip this entry, to avoid logging nonsensical errors.
       return;
@@ -2254,14 +2259,14 @@ shaka.media.DrmEngine = class {
     // The only way to get license servers from the manifest is not to specify
     // any in your player config.
 
-    if (drmInfo.keySystem == 'org.w3.clearkey' && drmInfo.licenseServerUri) {
+    if (originalKeySystem == 'org.w3.clearkey' && drmInfo.licenseServerUri) {
       // Preference 1: Clear Key with pre-configured keys will have a data URI
       // assigned as its license server.  Don't change anything.
       return;
     } else if (servers.size) {
       // Preference 2: If anything is configured at the application level,
       // override whatever was in the manifest.
-      const server = servers.get(drmInfo.keySystem) || '';
+      const server = servers.get(originalKeySystem) || '';
 
       drmInfo.licenseServerUri = server;
     } else {
@@ -2273,7 +2278,7 @@ shaka.media.DrmEngine = class {
       drmInfo.keyIds = new Set();
     }
 
-    const advancedConfig = advancedConfigs.get(drmInfo.keySystem);
+    const advancedConfig = advancedConfigs.get(originalKeySystem);
 
     if (advancedConfig) {
       if (!drmInfo.distinctiveIdentifierRequired) {
@@ -2307,6 +2312,10 @@ shaka.media.DrmEngine = class {
       }
     }
 
+    if (keySystemsMapping[originalKeySystem]) {
+      drmInfo.keySystem = keySystemsMapping[originalKeySystem];
+    }
+
     // Chromecast has a variant of PlayReady that uses a different key
     // system ID.  Since manifest parsers convert the standard PlayReady
     // UUID to the standard PlayReady key system ID, here we will switch
@@ -2315,7 +2324,7 @@ shaka.media.DrmEngine = class {
     // player config uses the standard PlayReady ID for license server
     // configuration.
     if (window.cast && window.cast.__platform__) {
-      if (drmInfo.keySystem == 'com.microsoft.playready') {
+      if (originalKeySystem == 'com.microsoft.playready') {
         drmInfo.keySystem = 'com.chromecast.playready';
       }
     }

lib/util/player_configuration.js

@@ -74,6 +74,7 @@ shaka.util.PlayerConfiguration = class {
       logLicenseExchange: false,
       updateExpirationTime: 1,
       preferredKeySystems: [],
+      keySystemsMapping: {},
     };
 
     const manifest = {

test/demo/demo_unit.js

@@ -94,7 +94,8 @@ describe('Demo', () => {
           .add('playRangeStart')
           .add('playRangeEnd')
           .add('manifest.dash.keySystemsByURI')
-          .add('manifest.hls.mediaPlaylistFullMimeType');
+          .add('manifest.hls.mediaPlaylistFullMimeType')
+          .add('drm.keySystemsMapping');
 
       /**
        * @param {!Object} section