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Emmanuel Weber - Blue Jeans 10/15/2014
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Emmanuel Weber
10/15/2014
Optimizing Real Time Interactive Video Delivery from the Cloud
Highlights
Cloud based video conferencing solutions are some of the latest novelties in bidirectional real-time video.
Because of the unprecedented scale of those solutions and new type of deployments, there is an opportunity to revisit old problems and provide some new answers to them. This is particularly true in the area of real-time video delivery.
Problems affecting video delivery
Traditional problems: Bandwidth Loss Jitter Out of order packets Duplicate packets Congestion Problems specific to the “last mile”: Congested Wifi Restricted firewall
Brief history of video deployments
Roughly three phases:
Private controlled network
Hosted
Cloud + over the top (OTT) over Internet
Private / Controlled network
The network is fully controlled by enterprise IT
Can implement QoS techniques and dimension the network in such a way that most problems affecting video quality are solved
Doesn’t work well for interactions with parties outside of the controlled network (difficult to setup call and overall quality concerns).
Private / Controlled network
Private Deployment
Hosted
Same software used in private deployment is used in a remote location often accessed over the Internet.
Software is maintained by a third party.
Solution usually not designed to handle Internet traffic or difficult network.
Somewhat worst of both worlds in term of video delivery. Lose benefit of controlled environment and external party does not necessarily see improvements in terms of video quality.
Hosted Deployment
Data Center
Traditional cloud base solution
Dedicated software designed for Internet traffic.
Solution is distributed geographically in multiple data centers to get closer to endpoints.
Traffic can be routed between data centers to optimize network path between endpoints.
Traditional Cloud Base solution
Data Center
Data Center
Cloud based / CDN type deployment
It is possible to improve the video delivery one step further by breaking down the problem once more.
By pushing some of the functionality as close as possible to the endpoints, overall video performance can be greatly improved.
This can be accomplished by a “transparent relay (TR)” that funnels RTP/RTCP streams.
TR ideally should be located as close as possible to the endpoint. This is very similar in concept to traditional CDN solution for video streaming.
Cloud based / CDN type deployment
TR
TR
TR
TR
TR
TR
TR
TR
TR
Data Center
Data Center
Transparent Relay (TR)
MANE type device
As close as possible to the endpoint
Many deployed across the globe. The shorter the round-trip time between the TR and the endpoint, the better.
Provides several benefits: • Error resilience schemes
• Better bandwidth predictor (early congestion detection)
• Better network control (Ex: avoid overloaded peering point)
• Network analytics
Transparent Relay
Packet Queue
RTX FEC
SRTP
Ban
dw
idth
Es
tim
ato
r
Control
Endpoint Cloud RTP/RTCP
RTP/RTCP
Control
• TR is mostly concerned with RTP/RTCP traffic. No control connection between the endpoint and the TR.
• Control connection between the TR and rest of the cloud software. Used to receive configuration such as payload information, encryption keys etc.
• Some lightweight processing (FEC, SRTP) • Network path between TR and rest of the cloud infrastructure is managed by the cloud
operator.
Error resilience schemes
TR can implement several error resilience schemes
Retransmission (RTX) • Particularly effective due to the low delay between the TR and the
endpoint.
Forward error correction (FEC) • Can be generated relatively cheaply in terms of computational power
at the edge of the network to protect the stream.
Stream shaping • TR can shape the video stream when scalable media is used.
Bandwidth predictor
By being closer to the endpoint, there is less network uncertainty.
Bandwidth estimation using indirect methods like delay detection are more accurate and can react quicker to any congestion.
Bandwidth probing is also more reliable.
Better network control
Cloud provider can manage the network infrastructure dynamically with fewer unknown third parties.
In the extreme case, the TR is on the customer premise. This can provide almost the same reliability as private network deployment.
Connections that uses TCP or HTTPS to go through a restricted firewall are terminated earlier greatly improving TCP performance.
Network Analytics
The TR can provide analytics on the quality of the network.
By reacting to those analytics, the cloud operator can adapt its network infrastructure and improve the overall delivery of the video
• Chose alternate provider or network path to serve some areas
• Route calls to a different geography
• …
Conclusion
Using existing technologies, rethinking the video infrastructure in a cloud based context makes it possible to deliver real-time bidirectional video very efficiently.
Cloud based delivery is a relatively new area. There is plenty of room for improvement.