Make imscJS style options generic

Author: ryanmccartney

src/core/Settings.js

@@ -513,12 +513,8 @@ import Events from './events/Events';
  * When true, only those captions where itts:forcedDisplay="true" will be displayed.
  * @property {boolean} [imsc.enableRollUp=true]
  * Enable/disable rollUp style display of IMSC captions.
- * @property {number} [imsc.options.sizeAdjust=1]
- * IMSC styling options - adjust text size, scales the text size and line padding 
- * @property {number} [imsc.options.lineHeightAdjust=1]
- * IMSC styling options - scales the line height 
- * @property {number} [imsc.options.backgroundOpacityScale=1]
- * IMSC styling options - scales the backgroundColor opacity 
+ * @property {number} [imsc.options]
+ * IMSC styling options - including; sizeAdjust, lineHeightAdjust, backgroundOpacityScale and fontFamily. See the renderHtml function of imscJS for full details 
  * @property {object} [webvtt.customRenderingEnabled=false]
  * Enables the custom rendering for WebVTT captions. For details refer to the "Subtitles and Captions" sample section of dash.js.
  * Custom WebVTT rendering requires the external library vtt.js that can be found in the contrib folder.
@@ -1015,11 +1011,7 @@ function Settings() {
                 imsc: {
                     displayForcedOnlyMode: false,
                     enableRollUp: true,
-                    options: {
-                        sizeAdjust: 1,
-                        lineHeightAdjust: 1,
-                        backgroundOpacityScale: 1
-                    },
+                    options: null,
                 },
                 webvtt: {
                     customRenderingEnabled: false