vedantu @ kranky geek

www.vedantu.com

Introduction

Marketplace of Teachers

Growth

300Hours in a Day

10000+ Hours in a Month

Live Classroom

Models

One to One - P2P

Signalling Server(Node.js)

coTURN Server

SignallingWhiteboard Data

StatisticsRecording

SignallingWhiteboard Data

StatisticsRecording

MediaTeacherStudentN

AT

NAT

❏ Requirements❏ Session replay❏ Academic Review❏ Engagement analysis

❏ P2P WebRTC and recording❏ Local storage of recordings❏ Time to upload recordings❏ Dependent on teacher & student to upload independent streams❏ Huge size of recordings

❏ Convert audio to mp3 sampled at 8000 Hz❏ Mobile CPU consumption to reduce audio upload size

Recording

Models

One to One & One to Few Media Server

Media Server

Teacher

StudentStudent

Signalling Server MediaMedia

Media

One to Few:P2P mesh not an option

Media ServerCentral recording, SimulcastEvaluation of Jitsi / 3rd party

Academic Quality

Verbal Interaction Whiteboard Usage Content Usage

- Conversation Analysis- Tone Analysis- Pace Analysis

- Space Usage- Handwriting- Activity

- Images and Shapes- Annotations

Flagging, Reporting, Quality Control

Session Quality

[TBD] All statistics we collect - graphical representation

★ Disconnects and Statistics★ Support★ Correlation with Engagement Analysis

WebRTC on Mobile

❏ Generate binaries for android using depot tool

❏ Support x86, ARM architectures ❏ Increased app size by ~5 MB

❏ Average session duration 60 mins❏ 300+ hours of live sessions in last 3

months❏ Statistics (1 hr. session)

❏ 15-20% battery consumption❏ 2-3 network disconnections

Statistics

Average Session Length 60 mins

TURN usage 24%

Disconnects / Session 1.46

Cloud telephony calls (bad networks) 5.3%

Initial connection establishment 1.7 sec

RTT 272 ms

Jitter 7 ms

Packet loss 0.08%

Issues

❏ Browser updates and compatibilityFirefox - Delay in permission popupFirefox - BugID:852665 - Report WebRTC transport termination

❏ P2P - Session RecordingRemote stream recording API (recently available in Chrome 49)Storage and Replay for P2P

❏ RTC Data connection cannot be used for Whiteboard dataFirefox issue - ICE state changes not detectedApplication level keep-alive (ping pong) for detecting connection stateIssue with reconnect and performance

Look forward to

❏ VP9 and all its goodness

❏ Call summary❏ Quality - MOS, PESQ score❏ Jitter❏ Packet loss❏ RTT❏ Bandwidth❏ Duration

❏ API for bandwidth limiting instead of SDP munging

Journey ahead

❏ Build the Knowledge sharing network

❏ Connect at scale

❏ Truly democratize education

THANK YOU