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Learn about why Mesh may not be the answer for #WebRTC and why the better approach is to centralize and mix all the media in an MCU. As well as an in-depth explanation on the benefits of using an MCU. As presented by Chad Hart at WebRTC Expo V.
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COMPANY CONFIDENTIAL © COPYRIGHT 2014 DIALOGIC INC. ALL RIGHTS RESERVED.
D3-4 Media Services -Beyond the MCU
Chad Hart
WebRTC Expo V
COMPANY CONFIDENTIAL © COPYRIGHT 2014 DIALOGIC INC. ALL RIGHTS RESERVED. 2Image source: http://thewrestlinglifeupdate.tumblr.com/
Multi-PARTY! Video Conferencing
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Easy & cheap approach to multi-party: Mesh
3
Full Mesh
Works for a few parties
No server cost
Lowest latency
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Mesh does not scale for many video conferees
4
Full Mesh
Clients get overloadedEncode costs more than decode
Limited uplink bandwidth
Inconsistent performance across participants
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Traditional Telephony Approach: MCU
5
Multipoint Control Unit (MCU)Good at manipulating all media
Transcoding
Transizing
Transrating
Interworking
Server-side CPU intensive
Client can request different conference mixes
Usually client friendly
Downsizing & mixing can reduce bandwidth
Fewer client streams to process
MCU
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Traditional MCU resource usage
6
Worst-case process:1. Each stream decoded
at the MCU
2. MCU mixes each conferee
3. MCU encodes individual mix for each conferee
MCU
1
1 22
3
3
44
5
5
6
6
Ingress streams 6
Egress streams 6
MCU decodes 6
MCU encodes 6
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Efficient MCU resource usage
7
Efficient process:1. Each stream decoded
at the MCU
2. MCU mixes each conferee
3. MCU shares same encoder for all conferees
MCU
12
3
45
6
Ingress streams 6
Egress streams 6
MCU decodes 6
MCU encodes 1
1
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Resource efficient MCU with encoder sharing
30%-50% reduction in compute resources
0%
20%
40%
60%
80%
100%
1 2 3 4 5 6 7 8 9 10 11 15 17 20
Syst
em
CP
U U
tiliz
atio
n
Conferees
Encoder sharing vs. multi-encode
Traditional MCU Dialogic Evolved MCU
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Newer approach: SFU
9
SFU
Selective Forwarding Unit (SFU) routing
Clients send one & receive many
Client can instruct SFU which streams to send
High throughput
Can be lots of downlink bandwidth
Low latency
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Newer approach: SFU
10
SFU
Selective Forwarding Unit (SFU) routing
Clients send one & receive many
Client can instruct SFU which streams to send
High throughput
Can be lots of downlink bandwidth
Low latency
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New WebRTC approach: Simulcast
11
SFU
High bitrate
Low bitrate
Selective Forwarding Unit (SFU) with Simulcast
Clients send multiple streams to SFU
one high-bit rate
one or more lower-bit
Client directs SFU which streams to receive
Reduces bandwidth vs. SFU
Simulcast in WebRTC coming
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A look at Google Hangouts with Simulcast
http://webrtchacks.com/hangout-analysis-philipp-hancke/
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Future Approach with VP9 – SVC?
13
SFU
MediumHigh LowLayered bitrates:
Selective Forwarding Unit (SFU) with SVC
Clients send layered stream to SFU
Layers have varying bitrates –time, size, quality
SFU directs who gets what
Coming to WebRTC eventually
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Multi-party video summary comparison
http://networkfuel.dialogic.com/webrtc-whitepaper
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Building a compelling UX with a MCU
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Video UX: Traditional method
MCU1 2
3 4
Mixed stream 1 2
3 4
3G Device
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Video UX: Traditional method
MCU1 2
3 4
Mixed stream 1 23
3G DeviceActive Talker
Media Server Chooses Layout
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Client appApp Server2
Modern UX with MCU mixing, HTML5 & JavaScript
Browser
MCU1 2
3 4
HTML5 CanvasJavascript
Mixed stream
Application-defined UX
Layout
"Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
Benefits:
Application defined UX
User specific & customizable layout
Lower client BW & CPU vs. mesh
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What do you care more about?
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CPU & processing power is expensive
Client view Provider View
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Bandwidth is not always ubiquitous or free
Client-side Server-side
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Why do you need a media server?
Multi-party conferencing InterworkingTranscoding
Stream processing Person-to-machineRecording
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Case Study: Video Recording Service
Application highlightsRecord live events – E.g. Kids soccer gameShare event recording with family/friends – Multi-party stream
Supported Recording Formats
.3GP
.mp4
.wav
CodecsG.711, Opus, AMR-NB and AMR-WB (voice)VP8, H.264 (video)
Message StorageLocal storageRemote message deposit via MSRP
HTTP/MSRP
REST (HTTP)
Application Server
Media Server
Message Storage
RTP (media)
Solution HighlightsSoftware-based Media Server
Virtualized (VM) and COTS deployment
High Availability and Geographical Redundancy
Scalability via Media Resource Broker
Architected to support 3.5M Subscriber Network
Recording
Remote Message Deposit
Key Functions
Transcoding
WebRTC Signaling
WAN
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The future: gesture controls
https://github.com/mtschirs/js-objectdetect/
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The future: machine vision
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The future: augmented reality
http://jooink.blogspot.com/2012/10/gwt-augmented-reality-howto-step-1.html