feat(external_api) add ability to start transcriptions together with recordings

modules/API/API.js

 } from '../../react/features/participants-pane/actions';
 import { getParticipantsPaneOpen, isForceMuted } from '../../react/features/participants-pane/functions';
 import { startLocalVideoRecording, stopLocalVideoRecording } from '../../react/features/recording/actions.any';
-import { RECORDING_TYPES } from '../../react/features/recording/constants';
+import { RECORDING_METADATA_ID, RECORDING_TYPES } from '../../react/features/recording/constants';
 import { getActiveSession, supportsLocalRecording } from '../../react/features/recording/functions';
 import { startAudioScreenShareFlow, startScreenShareFlow } from '../../react/features/screen-share/actions';
 import { isScreenAudioSupported } from '../../react/features/screen-share/functions';
          * @param { string } arg.youtubeStreamKey - The youtube stream key.
          * @param { string } arg.youtubeBroadcastID - The youtube broadcast ID.
          * @param { Object } arg.extraMetadata - Any extra metadata params for file recording.
+         * @param { boolean } arg.transcription - Whether a transcription should be started or not.
          * @returns {void}
          */
         'start-recording': ({
             rtmpBroadcastID,
             youtubeStreamKey,
             youtubeBroadcastID,
-            extraMetadata = {}
+            extraMetadata = {},
+            transcription
         }) => {
             const state = APP.store.getState();
             const conference = getCurrentConference(state);
                     mode: JitsiRecordingConstants.mode.STREAM,
                     streamId: youtubeStreamKey || rtmpStreamKey
                 };
-            } else {
-                logger.error('Invalid recording mode provided');
-
-                return;
             }
 
             if (isScreenshotCaptureEnabled(state, true, false)) {
                 APP.store.dispatch(toggleScreenshotCaptureSummary(true));
             }
-            conference.startRecording(recordingConfig);
+
+            // Start audio / video recording, if requested.
+            if (typeof recordingConfig !== 'undefined') {
+                conference.startRecording(recordingConfig);
+            }
+
+            if (transcription) {
+                APP.store.dispatch(setRequestingSubtitles(true, false, null));
+                conference.getMetadataHandler().setMetadata(RECORDING_METADATA_ID, {
+                    isTranscribingEnabled: true
+                });
+            }
         },
 
         /**
          * Stops a recording or streaming in progress.
          *
          * @param {string} mode - `local`, `file` or `stream`.
+         * @param {boolean} transcription - Whether the transcription needs to be stopped.
          * @returns {void}
          */
-        'stop-recording': mode => {
+        'stop-recording': (mode, transcription) => {
             const state = APP.store.getState();
             const conference = getCurrentConference(state);
 
                 return;
             }
 
+            if (transcription) {
+                APP.store.dispatch(setRequestingSubtitles(false, false, null));
+                conference.getMetadataHandler().setMetadata(RECORDING_METADATA_ID, {
+                    isTranscribingEnabled: false
+                });
+            }
+
             if (mode === 'local') {
                 APP.store.dispatch(stopLocalVideoRecording());
 

modules/API/external/external_api.js

      * @param { string } options.youtubeStreamKey - The youtube stream key.
      * @param { string } options.youtubeBroadcastID - The youtube broadcast ID.
      * @param {Object } options.extraMetadata - Any extra metadata params for file recording.
+     * @param { boolean } arg.transcription - Whether a transcription should be started or not.
      * @returns {void}
      */
     startRecording(options) {
      * Stops a recording or streaming session that is in progress.
      *
      * @param {string} mode - `file` or `stream`.
+     * @param {boolean} transcription - Whether the transcription needs to be stopped.
      * @returns {void}
      */
-    stopRecording(mode) {
-        this.executeCommand('stopRecording', mode);
+    stopRecording(mode, transcription) {
+        this.executeCommand('stopRecording', mode, transcription);
     }
 
     /**