1 files changed, 67 insertions, 22 deletions

diff --git a/packages/meshbay-client/src/cast-chromecast.js b/packages/meshbay-client/src/cast-chromecast.js
index 50f79fd..2dd210f 100644
--- a/packages/meshbay-client/src/cast-chromecast.js
+++ b/packages/meshbay-client/src/cast-chromecast.js
@@ -6,6 +6,56 @@ const DefaultMediaReceiver = require('castv2-client').DefaultMediaReceiver;
 
 const SCAN_DURATION_MS = 6000;
 
+// The one track the receiver is ever told about. A side-loaded track cannot
+// have its cues replaced in place, so changing subtitles means loading again
+// with a new URL under this same id rather than adding a second track.
+const TEXT_TRACK_ID = 1;
+
+// White on nothing is unreadable over a bright scene, and the receiver's
+// default style is exactly that. An outline costs no bandwidth.
+const TEXT_TRACK_STYLE = Object.freeze({
+  backgroundColor: '#00000000',
+  foregroundColor: '#FFFFFFFF',
+  edgeType: 'OUTLINE',
+  edgeColor: '#000000FF',
+  fontScale: 1.0,
+  fontFamily: 'SANS_SERIF',
+});
+
+/**
+ * What to hand `player.load()` for a stream, with or without subtitles.
+ *
+ * `streamType: 'LIVE'` because the relay has no beginning to seek back to —
+ * the film's own timeline lives on this side, and a seek restarts the relay.
+ */
+function mediaFor(mediaUrl, subtitle) {
+  const media = {
+    contentId: mediaUrl,
+    contentType: 'video/mp4',
+    streamType: 'LIVE',
+  };
+  if (subtitle && subtitle.url) {
+    media.tracks = [{
+      trackId: TEXT_TRACK_ID,
+      type: 'TEXT',
+      trackContentId: subtitle.url,
+      trackContentType: 'text/vtt',
+      subtype: 'SUBTITLES',
+      name: subtitle.label || 'Subtitles',
+      language: subtitle.language || 'und',
+    }];
+    media.textTrackStyle = TEXT_TRACK_STYLE;
+  }
+  return media;
+}
+
+function loadOptionsFor(subtitle) {
+  return {
+    autoplay: true,
+    activeTrackIds: subtitle && subtitle.url ? [TEXT_TRACK_ID] : [],
+  };
+}
+
 class CastChromecast {
   constructor() {
     this._bonjour = null;
@@ -56,7 +106,7 @@ class CastChromecast {
     });
   }
 
-  async connect(deviceId, mediaUrl) {
+  async connect(deviceId, mediaUrl, subtitle) {
     const device = this._devices.get(deviceId);
     if (!device) throw new Error(`Unknown device: ${deviceId}`);
 
@@ -91,36 +141,29 @@ class CastChromecast {
       console.log(`[cast-chromecast] player status: ${status.playerState}`);
     });
 
-    const media = {
-      contentId: mediaUrl,
-      contentType: 'video/mp4',
-      streamType: 'LIVE',
-    };
-
+    console.log(`[cast-chromecast] loading with ${subtitle?.url ? 'subtitles' : 'no subtitles'}`);
     const status = await new Promise((resolve, reject) => {
-      player.load(media, { autoplay: true }, (err, s) => {
-        if (err) return reject(err);
-        resolve(s);
-      });
+      player.load(mediaFor(mediaUrl, subtitle), loadOptionsFor(subtitle),
+        (err, s) => {
+          if (err) return reject(err);
+          resolve(s);
+        });
     });
 
     console.log(`[cast-chromecast] loaded on "${device.name}", state: ${status.playerState}`);
     return { deviceName: device.name, playerState: status.playerState };
   }
 
-  async reload(mediaUrl) {
+  async reload(mediaUrl, subtitle) {
     if (!this._player) throw new Error('Not connected');
-    console.log(`[cast-chromecast] reloading stream on "${this._connectedDevice?.name}"`);
-    const media = {
-      contentId: mediaUrl,
-      contentType: 'video/mp4',
-      streamType: 'LIVE',
-    };
+    console.log(`[cast-chromecast] reloading stream on "${this._connectedDevice?.name}"`
+      + ` with ${subtitle?.url ? 'subtitles' : 'no subtitles'}`);
     const status = await new Promise((resolve, reject) => {
-      this._player.load(media, { autoplay: true }, (err, s) => {
-        if (err) return reject(err);
-        resolve(s);
-      });
+      this._player.load(mediaFor(mediaUrl, subtitle), loadOptionsFor(subtitle),
+        (err, s) => {
+          if (err) return reject(err);
+          resolve(s);
+        });
     });
     console.log(`[cast-chromecast] reloaded, state: ${status.playerState}`);
     return { playerState: status.playerState };
@@ -155,3 +198,5 @@ class CastChromecast {
 }
 
 module.exports = CastChromecast;
+module.exports.mediaFor = mediaFor;
+module.exports.loadOptionsFor = loadOptionsFor;