Video on Demand over the InternetTrends and challenges

Juergen Ehrensberger (HEIG-VD)Andrés Revuelta (EIG)

Jean-Roland Schuler (EIA-FR)

November 2006

Project Vadese

« Video on Demand and Security » http://www.vadese.org

• Two-years research project• 4 research groups from 3 different schools

(Fribourg, Geneva, Yverdon)• Focuses on the needs of VoD services providers

– Quality of Service – Patching over Peer-to-peer– Digital Rights Management

Video over the Internet

31 October 2006:Swisscom launches Bluewin TV

Video over the Internet

July 2006:Deutsche Telekom launches IPTV

Video over Internet – Market studies

IPTV« Television broadcast over the Internet access »– Worldwide market size (Gartner 2006)

• $870 million in 2006• $13 billion in 2010

Video on Demand« Download or streaming of movies at any time »– Worldwide market size (iSuppli 2006)

• 40% growth in 2005• $2 billion in 2006• $13 billion in 2010

Another market study...

Media distribution over the Internet

Media can be transferred by download or streaming

Download– A file is downloaded from a server to the customer’s equipment– The media can be consumed only after the download has finished

Simple Not suited for live content Long waiting time

Streaming– A continuous media flow of packets is transferred from a server to the customer– The customer consumes the media simultaneously with the transfer

Suited for live content Technically challenging

Network scenario

ISP 1 ISP 2

ISP 3

Home network

Service provider

Low-speed access link(ADSL, CaTV)

High-speed access

TVSet-Top Box

Home network

TVSet-Top Box

Video server

Internet

Quality of Service

• The main challenge of streaming media over this Internet is to obtain a sufficient Quality of Service :

« QoS is the collective effect of service performance which determines

the degree of satisfaction of a user of a service »

(ITU-T Rec. E-800)

Measurable performance parameters

Throughput– ‘Speed’ of the transmission, bits per second received

Packet loss rate– Percentage of packets lost inside the network

Network delay– Delay between the sending of a packet at the source and the

reception by the receiver Delay variation

– Changes of network delay between successive packets

Throughput• Media streams have an inherent bitrate that has to be provided by the

network

Throughput requirements

Transmission capacity

Codec Quality BitrateMPEG-2 TV quality 1 – 4 Mb/sMPEG-4 AVC TV quality 768 kb/sMPEG-4 AVC HDTV 5 – 6 Mb/s

Network Capacity MPEG-4 TV flowsADSL 3 Mb/s 4 flowsEthernet 100 Mb/s 130 flowsISPs / Internet 10 Gb/s 13’000 flows

Packet loss

• What happens if there is too much traffic in the network?– The Internet is a network of transmission links,

connected to routers

Home network

Internet Company network

Company network

Packet loss

• What happens if there is too much traffic in the network?– Each router receives traffic from several input links and

forwards the packet to output links

Packet loss

• What happens if there is too much traffic in the network?– If the output link is occupied, packets have to wait for

transmission in a queue

Packet loss• Transmission queues on routers are causing

packet loss and delays

Measurement over low-capacity access links

Up to 5% packet loss20ms one-way delay

InternetISP

Home network

ADSL (3Mb/s)

HEIG-VD

Access 100 Mb/s

Packet loss, delays

Router

Effect of packet loss on video quality

Example: – 1% loss – MPEG-2– No error concealment

Example: – 5% loss – MPEG-2– No error concealment

Effect of network delay

• Network delay is not critical for non-interactive applications– Typically network delay is below 1 seconds– User may tolerate several seconds of delay

Possible problems– « Roberto Baggio Effect »– Channel switching delay

Delay variation

• Media playback requires a constant flow of data• The packets of the media flow experience different network delays

• A playout buffer compensates the delay variations• Half-filled upon start of the transmission (« Buffering... ») Increases network delay

– Delay variations should be small to keep playout buffer small

Internet

SenderReceiver

Isochronous flow

Isochronous flow

Variable network delays

Playout buffer

Playback application Source application

Current challenges

Insufficient QoS over ADSL and CaTV– Overdimensioning or VDSL– QoS mechanisms in the ISP network– QoS mechanisms on user’s Set-Top Box

High cost for streaming individual flows– « Patching » of video flows– Peer-to-peer distribution of flows

Digital Rights Management

Overdimensioning of the access link

• ADSL link with 3 Mb/s• MPEG-4 AVC video with TV quality at 768 kb/s Additional traffic (Web, E-mail, downloads) may deteriorate the video quality

InternetISP

Home network

ADSL (3Mb/s) Access 100 Mb/s

Service provider

TV Set-Top Box Video server

Dynamic overdimensioning• ISP dynamically increases ADSL capacity

during video streaming– Should provide sufficient capacity for

video and additional downloadsProblem: traffic demand adapts to available

capacity

Very High Bitrate DSL (VDSL2)• Provides capacity of 20 Mb/s (over 1500m)• Allows simultaneous transmission of 2

HDTV channels• Problem: high investment required to

upgrade the access network

QoS mechanisms in the ISP network

ISP Home network

Set-Top Box

• Even over ADSL, a sufficient QoS can be provided using QoS mechanisms• Idea: give video flow priority over other traffic

– Video flow gets sufficient capacity to avoid packet loss on the ADSL link– Other traffic (Web, download) is still possible, but slower

QoS mechanisms in the ISP network

• Even over ADSL, a sufficient QoS can be provided using QoS mechanisms• Idea: give video flow priority over other traffic

– Video flow gets sufficient capacity to avoid packet loss on the ADSL link– Other traffic (Web, download) is still possible, but slower

ISP Home network

Set-Top Box

High priority queue

Low priority queue

Video flow

Other traffic

QoS mechanisms on user’s Set-Top Box• Solution developed in Vadese• Modifications of the access network are costly• Service providers do not own the access network• How can a service provider offer sufficient QoS?

– Use QoS mechanisms on the Set-Top Box Has to control traffic after it has crossed the ADSL link!

ISP Home network

Set-Top Box

Video flow

Other traffic

QoS mechanisms on user’s Set-Top Box

• Non-video traffic mainly uses TCP– TCP adapts to network congestion, detected by packet loss

• Control queue length on ISP router from Set-Top Box– « Split » Advanced Queue Management

ISP Home network

Video flow

Other traffic

Low queue occupancy

Discard non-video packets

Controled TCP traffic

Measure video QoS

High cost for Video-on-Demand• In VoD, customers access videos at different moments• The simple approach to start a new flow for each user is not

economical– Example : access link at 1 Gb/s

Only 200 simultaneous HDTV flows (at 5 Mb/s)Cost of $1 per video, only for transmission

Internet

High-speed access 1 Gb/s

Service provider

Video server

Near Video-on-Demand with Multicast• Solution

– A new flow for the same video starts every n minutes– Similar to a TV broadcast that repeats every n minutes– Flow is efficiently transmitted via multicast

• Multicast is only feasible for network operators

Service provider

Video server

Home network

Home network

Set-TopBox

Set-TopBox

Multicast flow

Video patching with Peer-to-peer• Solution developed in Vadese• Allows true Video-on-Demand • Can be used by service providers without their own multicast network• Idea of patching:

– A customer who already receives a video can relay the flow to a new customer– The missing part of the video is temporarily ‘patched’ from the server

Service provider

Video server

Home network

Home network

Set-TopBox

Set-TopBox

Patching flow

Peer-to-peer flow

True Video-on-Demand with Multicast• Possible alternative to Peer-to-peer transmission• Combines Multicast and Patching to achieve true Video-on-Demand• Solution

– A new multicast flow for the same video starts every n minutes– When a new customer arrives, it joins an existing multicast session– The missing first minutes of the movie is patched by a short-lived patching flow

Service provider

Video server

Home network

Home network

Set-TopBox

Set-TopBox

Multicast flow

Patching flow

Joins multicast

Conclusion

Project Vadese - Video on Demand and Security– Focuses on the needs of VoD services providers

• Quality of Service • Patching over P2P• Digital Rights Management

– Technologies will be integrated in a Set-Top Box– Possible valorizations

• Follow-up projects with commercial partners• Intellectual property• Commercialization of some of the technologies