Slides of the corresponding presentation at webRTC Conf. and Expo June 2014.

1. Scaling Video
Infrastructure
Dr. Alex Gouaillard
CTO Temasys Communications

2. Limits of P2P
Other interesting configurations / use cases
MCU internals
Open Source MCUs

3. Limits of P2P
Other interesting configurations / use cases
MCU internals
Open Source MCUs

4. Limits of P2P: client side scalability
Alice Bob
Alice Bob
Chris
Alice Bob
Chris David
2
6
12
Alice
Bob
Chris
EdDave
20
n(n-1) O(n^2)

5. Business as usual MCU: multiplexing streams
- wow, super bandwidth !
- Hum, wait, what about latency?
- What happen if peers are far away …. ?
- Interface layout ??
=> CP, VAS
Ok, that’s great but ….
- Chat? I mean, if only to pass a link
- Collaboration (white board?)
- Services other than A/V?
- Usage beyond the boardroom model: BYOD device, work from home, ….
Alice
Bob
Chris
EdDave
MCU
5
n O(n)

6. Smarter topology ?
Alice
Bob
Chris
EdDave
broad
cast
12,5
(n^2)/2 O(n^2)
type
Streams
IN
Streams
OUT
p2p N-1 N-1
MCU 1 1
Hybrid N-1 1

7. Smarter topology ?
- bandwidth optimization WITH layout freedom
0
100
200
300
400
500
600
2 7 12 17 22
type
Streams
IN
Streams
OUT
p2p N-1 N-1
MCU 1 1
Hybrid N-1 1

8. Limits of P2P
Other interesting configurations / use cases
MCU internals
Open Source MCUs

9. Broadcast / seminar
Prof
Broad
cast
Broad
cast
Broad
cast
Broad
cast
Broad
cast
S
S
S
S
S
S
S
SS
S
S
S
SS
S
S

10. Heterogeneous – Bandwidth, CPU, Display - Concept
Desk.
Desk.
Cr.
Book
Mobil
e
Mobil
e
MCU
HD
HD
SD
QVGA
QVGA

11. Heterogeneous – Case 1: simulcast
The user send the same stream at different resolutions
Pro: easy on the server side (switch)
Cons: overhead on client (still better than p2p)
Desk.
HD
MCU
SD
QVGA
Cr.
Book
Mobile
Desk.
HD
SD
QVGA

12. Heterogeneous – Case 2: video Proc. In MCU
Scale down and/or drop frames in the MCU
Pro: no overhead on client
Con: full overhead on server
(need access to raw frame)
Desk. MCU
HD Cr.
Book
Mobile
Desk.
HD
SD
QVGA

13. Heterogeneous – Case 3: streams management In MCU (SVC)
- PRO: Only 30% overhead on client.
- PRO: No need for raw media on server

14. Limits of P2P
Other interesting configurations / use cases
MCU internals
Open Source MCUs

15. MCU Internals – The Onion
decryptunstream unload
UDP
TCP
TLS
SRTP RTP VP8
Decode
MAGIC
Raw Media
loadencode encrypt
VP8 RTP SRTP
stream
UDP
TCP
TLS

16. MCU Internals – Variation 1: old school MCU
decryptunstream unload
UDP
TCP
TLS
SRTP RTP VP8
Decode
Scale &
Rotate
Raw
Media
loadencode encrypt
VP8 RTP SRTP
stream
UDP
TCP
TLS
decryptunstream unload
UDP
TCP
TLS
SRTP RTP VP8
Decode
Scale &
Rotate
Raw
Media
decryptunstream unload
UDP
TCP
TLS
SRTP RTP VP8
Decode
Scale &
Rotate
Raw
Media

17. MCU Internals – Variation 2: relay / TURN
decryptunstream unload
UDP
TCP
TLS
SRTP RTP VP8
Decode
MAGIC
Raw Media
loadencode encrypt
VP8 RTP SRTP
stream
UDP
TCP
TLS

18. MCU Internals – Variation 3: Broadcast
unstream
UDP
TCP
TLS
stream
UDP
TCP
TLS
multicopy
stream
UDP
TCP
TLS
stream
UDP
TCP
TLS
stream
UDP
TCP
TLS
stream
UDP
TCP
TLS

19. MCU Internals – Variation 4: Recording
decryptunstream unload
UDP
TCP
TLS
SRTP RTP VP8
Decode
record
Raw Media

20. MCU Internals – Variation 5: Transcoding
decryptunstream unload
UDP
TCP
TLS
SRTP RTP VP8
Decode
Raw Media
loadencode encrypt
H264 RTP SRTP
stream
UDP
TCP
TLS

21. Limits of P2P
Other interesting configurations / use cases
MCU internals
Open Source MCUs

22. Foreword on Open Source MCUs
● All Chrome/Mozilla ready (except Jitsi)
● No data channel (Janus is the closest to have it)
● None gave huge CPU saving but expect bandwidth saving

23. Kurento (Total files:210/LoC:25000) - JAVA
PROS CONS
● Licensed under L-GPL License.
● 2$M EUR support from EU
● Using GStreamer
● Developers answering quickly
● Large project, Complicated design
● no low level API
● 3 entities: Web Server -> Connector-
>Media Server
● Academic driven.
● Webrtc Loopback to Http player. Http player = possibility to integrate into IE or Safari but latency of 5 secs.
Currently there is a bug on the IE/Safari support.
● Audio + Video recorder into webm or mp4 format (one user only)
Currently the javascript API is “one user only”. This means that it is not possible to mix source of different session
(availability expected: end of the month).
Available with the JAVA API:
● Video conferencing up to 4 peers

24. Licode/ Lynckia (Total files:110/LoC:26000) – C++
PROS CONS
● MIT License ● No working example/demo
● Project dead? (last commit on the
MCU 2 months ago:
https://github.com/ging/licode/tree/m
aster/erizo)
Personal Comment: Even the demos on their website are down: http://chotis2.dit.upm.es/

25. Jitsi (Total files:15/LoC:8000) - JAVA
PROS CONS
● Licensed under MIT license
● Small code base
● Bandwidth improvement
● XMPP (federation, presence, …)
● Installation can be difficult
● No real CPU improvement
What I did with it/Available demos tested:
● Video conferencing https://meet.jit.si/

26. Janus (Total files:30/LoC:14,000) - C
PROS CONS
● Low level. CPU efficient.
● Easy to install/use
● Bandwidth management
● Easy Extension through plugin arch.
● Developer answering FAST.
● License: GPL
• Each function needs to be a plugin
Personal Comment: I have been able to test many functionalities and easily. After one day studying the
source code I’m able to understand the main functionalities
What I did with it/Available demos tested:
● Video/Audio conferencing with control for the number of publisher (1 publisher = broadcasting) and number of
person in the room
● Screensharing
● Streaming Audio file: on demand (different streaming contexts for each client) or live (same streaming context for
each client)
● Streaming rtp source using a rtp source generator (gstreamer = audio+video -> gateway -> clients)
● Audio conferencing: mix all audio of other peers into one audio stream. Possible to record the audio into wav.
● Audio recording into .opus format
● NOT TESTED Sip Gateway (works with Asterisk)

27. QUESTIONS
THANK YOU!