WebRTC webinar talking about the status of Simulcast in the standards and browser implementations. We also explain what simulcast is, the use cases and what simulcast isn't. Webinar is part of the monthly WebRTC live Q&A sessions by Alex Gouailard, Dan Burnett and Amir Zmora

1. WebRTC Standards &
Implementation Q&A
Amir Zmora
TheNewDialTone
Dan Burnett
StandardsPlay
Alex Gouaillard
WebRTC by Dr Alex / Citrix

2. Watch video recording of this session
http://ccst.io/e/webrtcstandards7

3. Session sponsored by
WebRTC.ventures is a custom design and development shop dedicated to building WebRTC based applications
for web and mobile. We have built end-to-end broadcast solutions for events and entertainment clients,
telehealth solutions for multiple clients, live support tools, as well as communication tools for a variety of other
applications. WebRTC.ventures is a recognized development partner of TokBox and has also built native
WebRTC solutions

4. Session sponsored by
Blacc Spot Media is comprised of a collaborative team of designers, developers and thought leaders specializing
in Web-Real Time Communications (WebRTC). Blacc Spot Media was founded in April 2011 with the goal of
creating innovative solutions using new technologies such as WebRTC. Our team works on strategic projects
developing custom applications, enterprise platforms and mobile applications for a wide array of clients.

5. We use CrowdCast….It’s WebRTC

6. WebRTCStandards.info
Sponsored by

7. About Us
• Amir Zmora • Dan Burnett • Alex Gouaillard

8. Save The Date: September 12
Register Now: http://ccst.io/e/webrtcstandards8
Next Session

9. On The Agenda:
WebRTC Simulcast Standards &
Implementation

10. Simulcast is…
Image: John Fowler

11. Simulcast is not…
• Multiple streams of different sources (e.g. 2 cameras)
• Multiple participants
• SVC

12. Simulcast in the Standards

13. Simulcast Standards – API level
• WebRTC only supports SENDING of simulcast (for now . . .)
• Remember, simulcast is SINGLE SOURCE, MULTIPLE ENCODINGS
• So, the controls appear on RTCRtpSenders.
• BUT 'rid' (below) can only be used in addTransceiver or addTrack, NOT via
sender.setParameters()
• Controls are
• 'rid': user-definable label for the encoding
• 'scaleResolutionDownBy': base resolution will be divided by this value for this encoding
• (other encoding params such as maxBitrate, maxFramerate also still allowed)

14. In code . . .
navigator.mediaDevices.getUserMedia({ "audio": true, "video": true })
.then(function (stream) {
pc.addTransceiver(stream.getVideoTracks()[0], {
sendEncodings: [
{rid: "f"},
{rid: "h", scaleDownResolutionBy: 2.0},
{rid: "q", scaleDownResolutionBy: 4.0}
]
});
});

15. Simulcast Standards – Protocol level
• Still under discussion, but here's a rough
example:
a=rtpmap:97 H264/90000
a=rtpmap:98 H264/90000
a=fmtp:97 profile-level-id=42c01f; max-fs=3600; max-mbps=108000
a=fmtp:98 profile-level-id=42c00b; max-fs=240; max-mbps=3600
a=imageattr:97 send [x=1280,y=720] recv [x=1280,y=720]
a=imageattr:98 send [x=320,y=180] recv [x=320,y=180]
a=rid:1 pt=97
a=rid:2 pt=98
a=simulcast:send 1;2 recv 1

16. Implementing Simulcast

17. Reminder: Multiparty vs Simulcast vs SVC
© Dr. Alex Gouaillard @ Citrix Systems, 2015. Document provided under CC BY-NC 4.0
A
B
C
Multiparty
• Several tracks
• Decodable separately
• Bandwidth management separated
HD
SD
QVGA
Simulcast
• Several tracks
• Coming from the same source
• Decodable separately
• Smart bandwidth management possible
1SSRC
Δ2
Δ1
QVGA
SVC Encoding
• Several tracks
• Coming from the same source
• Not Decodable separately (Except base layer)
• Smart bandwidth management mandatory
• Less bandwidth, more resilience.
1SSRC
E
E
E
E
E
E
SVCEnc.
D
D
D
HD
SD
QVGA

18. Reminder
State of Multiparty signaling
© Dr. Alex Gouaillard @ Citrix Systems, 2015. Document provided under CC BY-NC 4.0
From the beginning of WebRTC, one have been able to send multiple media streams in separate peer
connections, but it consumes much more ports, and there is no sync between those tracks (lip sync, ..).
A
B
C
E
E
E
Multicast
• Several tracks
• Decodable separately
• Bandwidth management separated

19. Reminder
State of Multiparty signaling
For multiple streams in a single peer connection!
© Dr. Alex Gouaillard @ Citrix Systems, 2015. Document provided under CC BY-NC 4.0

20. Reminder: Multiparty vs Simulcast vs SVC
© Dr. Alex Gouaillard @ Citrix Systems, 2015. Document provided under CC BY-NC 4.0
A
B
C
Multicast
• Several tracks
• Decodable separately
• Bandwidth management separated
HD
SD
QVGA
Simulcast
• Several tracks
• Coming from the same source
• Decodable separately
• Smart bandwidth management possible
1SSRC
Δ2
Δ1
QVGA
SVC Encoding
• Several tracks
• Coming from the same source
• Not Decodable separately (Except base layer)
• Smart bandwidth management mandatory
• Less bandwidth, more resilience.
1SSRC
E
E
E
E
E
E
SVCEnc.
D
D
D
HD
SD
QVGA

21. Simulcast: Use case for webRTC 1.0
- Use Case for WebRTC 1.0: SFU
- Browser send simulcast,
does not receive simulcast
(in webrtc 1.0)
Desk.
HD
SFU
SD
QVGA
Cr. Book
Mobile
Desk.
HD
SD
QVGA
© Dr. Alex Gouaillard @ Citrix Systems, 2015. Document provided under CC BY-NC 4.0

22. Simulcast (and SVC later):
3 layers, 3 working groups, 2 standard bodies
- Separate the
- “on-the-wire” info (1),
- JS API (2),
- and signaling (3)
Signaling server
Web server
Bob
(device)
Alice
(browser)
Media
(3)
(2)
(1)
© Dr. Alex Gouaillard @ Cosmo Consulting., 2015. Document provided under CC BY-NC 4.0
© Dr. Alex Gouaillard @ Citrix Systems, 2015. Document provided under CC BY-NC 4.0

25. Save The Date: September 12
Register Now: http://ccst.io/e/webrtcstandards8
Next Session

26. Session sponsored by
WebRTC.ventures is a custom design and development shop dedicated to building WebRTC based applications
for web and mobile. We have built end-to-end broadcast solutions for events and entertainment clients,
telehealth solutions for multiple clients, live support tools, as well as communication tools for a variety of other
applications. WebRTC.ventures is a recognized development partner of TokBox and has also built native
WebRTC solutions

27. Session sponsored by
Blacc Spot Media is comprised of a collaborative team of designers, developers and thought leaders specializing
in Web-Real Time Communications (WebRTC). Blacc Spot Media was founded in April 2011 with the goal of
creating innovative solutions using new technologies such as WebRTC. Our team works on strategic projects
developing custom applications, enterprise platforms and mobile applications for a wide array of clients.

28. Thank You
Amir Zmora
TheNewDialTone
Dan Burnett
StandardsPlay
Alex Gouaillard
WebRTC by Dr Alex