Transcription Segment does have firat and last received time

[hahooh]

I am using Golang SDK and I want to know transcript starting and end time from ParticipantCallback.OnTranscriptionReceived. However, StartTime and EndTime is not supported yet.

So I want to make FirstReceivedTime and LastReceivedTime set from func ExtractTranscriptionSegments(transcription *livekit.Transcription) []*TranscriptionSegment.

I thought it would be great to have it since I want to have transcript starting time and end time (I think they are close enough).

So here is my suggestion.

Adding first_received_time and last_received_time to TranscriptionSegment message like below.

// protocol/protobufs/livekit_models.proto

// ... existing messages ...

message TranscriptionSegment {
  string id = 1;
  string text = 2;
  uint64 start_time = 3;
  uint64 end_time = 4;
  bool final = 5;
  string language = 6;
  int64 first_received_time = 7;
  int64 last_received_time = 8;
}

// ... existing messages ...

And handles in livekit-go-sdk like below.

Add below properties

	segmentTimestamps map[string]*segmentTimingInfo
	segmentMu         sync.RWMutex

to RTCEngine in https://github.com/livekit/server-sdk-go/blob/main/engine.go

set new type for segement time stamp like below

type segmentTimingInfo struct {
	firstReceivedTime int64
	lastReceivedTime  int64
}

and handle firstReceivedTime and lastReceivedTime before OnTranscription from func (e *RTCEngine) handleDataPacket(msg webrtc.DataChannelMessage) like below.

// ... existing code ...
	case *livekit.DataPacket_Transcription:
		now := time.Now().UnixMilli()
		e.segmentMu.Lock()
		for _, segment := range msg.Transcription.Segments {
			if timing, exists := e.segmentTimestamps[segment.Id]; exists {
				// Segment already seen - update last received time
				segment.FirstReceivedTime = timing.firstReceivedTime
				segment.LastReceivedTime = now
				timing.lastReceivedTime = now
			} else {
				// New segment - set both times to now
				segment.FirstReceivedTime = now
				segment.LastReceivedTime = now
				e.segmentTimestamps[segment.Id] = &segmentTimingInfo{
					firstReceivedTime: now,
					lastReceivedTime:  now,
				}
			}

			if segment.Final {
				delete(e.segmentTimestamps, segment.Id)
			}
		}
		e.segmentMu.Unlock()
		e.engineHandler.OnTranscription(msg.Transcription)
	case *livekit.DataPacket_RpcRequest:
// ... existing code ...

and extract first and last received time from func ExtractTranscriptionSegments(transcription *livekit.Transcription) []*TranscriptionSegment by adding two below properties to TranscriptionSegment and extract FirstReceivedTime and LastReceivedTime` from protobuf like below.

type TranscriptionSegment struct {
	ID                string
	Text              string
	Language          string
	StartTime         uint64
	EndTime           uint64
	Final             bool
	FirstReceivedTime int64
	LastReceivedTime  int64
}

func ExtractTranscriptionSegments(transcription *livekit.Transcription) []*TranscriptionSegment {
	var segments []*TranscriptionSegment
	if transcription == nil {
		return segments
	}
	segments = make([]*TranscriptionSegment, len(transcription.Segments))
	for i := range transcription.Segments {
		segments[i] = &TranscriptionSegment{
			ID:                transcription.Segments[i].Id,
			Text:              transcription.Segments[i].Text,
			Language:          transcription.Segments[i].Language,
			StartTime:         transcription.Segments[i].StartTime,
			EndTime:           transcription.Segments[i].EndTime,
			Final:             transcription.Segments[i].Final,
			FirstReceivedTime: transcription.Segments[i].FirstReceivedTime,
			LastReceivedTime:  transcription.Segments[i].LastReceivedTime,
		}
	}
	return segments
}

What do you think?