Add firstReceivedTime and lastReceivedTime to received TranscriptionS…

…egments (#1223)

* Add firstReceivedTime and lastReceivedTime to received TranscriptionSegements

* add changeset

* clear on disconnect

* set received time

.changeset/spotty-years-return.md

@@ -0,0 +1,5 @@
+---
+'livekit-client': patch
+---
+
+Add firstReceivedTime and lastReceivedTime to received TranscriptionSegments

src/room/Room.ts

@@ -162,6 +162,11 @@ class Room extends (EventEmitter as new () => TypedEmitter<RoomEventCallbacks>)
 
   private isResuming: boolean = false;
 
+  /**
+   * map to store first point in time when a particular transcription segment was received
+   */
+  private transcriptionReceivedTimes: Map<string, number>;
+
   /**
    * Creates a new Room, the primary construct for a LiveKit session.
    * @param options
@@ -174,6 +179,7 @@ class Room extends (EventEmitter as new () => TypedEmitter<RoomEventCallbacks>)
     this.options = { ...roomOptionDefaults, ...options };
 
     this.log = getLogger(this.options.loggerName ?? LoggerNames.Room);
+    this.transcriptionReceivedTimes = new Map();
 
     this.options.audioCaptureDefaults = {
       ...audioDefaults,
@@ -1274,6 +1280,7 @@ class Room extends (EventEmitter as new () => TypedEmitter<RoomEventCallbacks>)
     this.clearConnectionReconcile();
     this.isResuming = false;
     this.bufferedEvents = [];
+    this.transcriptionReceivedTimes.clear();
     if (this.state === ConnectionState.Disconnected) {
       return;
     }
@@ -1535,7 +1542,7 @@ class Room extends (EventEmitter as new () => TypedEmitter<RoomEventCallbacks>)
         : this.getParticipantByIdentity(transcription.transcribedParticipantIdentity);
     const publication = participant?.trackPublications.get(transcription.trackId);
 
-    const segments = extractTranscriptionSegments(transcription);
+    const segments = extractTranscriptionSegments(transcription, this.transcriptionReceivedTimes);
 
     publication?.emit(TrackEvent.TranscriptionReceived, segments);
     participant?.emit(ParticipantEvent.TranscriptionReceived, segments, publication);

src/room/types.ts

@@ -65,4 +65,6 @@ export interface TranscriptionSegment {
   startTime: number;
   endTime: number;
   final: boolean;
+  firstReceivedTime: number;
+  lastReceivedTime: number;
 }

src/room/utils.ts

@@ -532,15 +532,25 @@ export function toHttpUrl(url: string): string {
 
 export function extractTranscriptionSegments(
   transcription: TranscriptionModel,
+  firstReceivedTimesMap: Map<string, number>,
 ): TranscriptionSegment[] {
   return transcription.segments.map(({ id, text, language, startTime, endTime, final }) => {
+    const firstReceivedTime = firstReceivedTimesMap.get(id) ?? Date.now();
+    const lastReceivedTime = Date.now();
+    if (final) {
+      firstReceivedTimesMap.delete(id);
+    } else {
+      firstReceivedTimesMap.set(id, firstReceivedTime);
+    }
     return {
       id,
       text,
       startTime: Number.parseInt(startTime.toString()),
       endTime: Number.parseInt(endTime.toString()),
       final,
       language,
+      firstReceivedTime,
+      lastReceivedTime,
     };
   });
 }