Scalable Media Delivery on the Web with HTTP Server Push
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Scalable media delivery on the Web with HTTP Server Push Presentation to W3C Web5G Workshop 10th May 2018 Lucas Pardue Scalable media delivery on the Web with HTTP Server Push Motivation Life for broadcasters used to be simple… • Broadcasting from a terrestrial transmitter has a fixed cost. • The cost doesn’t depend on how many people tune in. The Internet doesn’t work like this! Source: BBC Scalable media delivery on the Web with HTTP Server Push The iPlayer service keeps getting more popular • Usage of the BBC iPlayer service is climbing steadily. • 272M on-demand programmes requested per month in 2017. • First episode of Blue Planet II was requested 4.8M times. • CDNs charge per byte delivered by the edge cache. The cost of providing the service rises in proportion to its popularity. Scalable media delivery on the Web with HTTP Server Push On-demand viewing is gaining ground… • For the main TV channels in the UK, live viewing …but linear viewing still dominates represents only 85% of consumption. • The remaining 15% is DVR time-shifting, 85% downloading and on- demand streaming. • Time-shifting works best for genres like drama, 15% comedy, entertainment and documentary. But linear viewing still plays a major role for news, sport and big events. Source: BARB Scalable media delivery on the Web with HTTP Server Push Linear television is still popular for big events • The BBC’s biggest streaming event to date was England vs. Wales in Euro 2016 England vs. Wales the Euro 2016 (2016-06-16) 9,300,000 competition. 10,000,000 Super Bowl 52 (2018-02-04) 8,000,000 • 2.3M simultaneous users. 6,000,000 120,000,000 103,400,0 00 4,000,000 2,300,000 • About 20% of total peak. 2,000,000 100,000,000 0 • Super Bowl 52 was iPlayer BBC One 80,000,000 (Live peak) (Live peak) watched by nearly fifty 60,000,000 Source: Radio Times times as many viewers. 40,000,000 • Streaming represented only 3% of total audience. 20,000,000 3,100,000 The potential audience for 0 Internet streaming Live broadcast linear streaming is huge and (peak) (average) scary. Source: AdWeek; USA Today Scalable media delivery on the Web with HTTP Server Push There are more and more bits to shift! • Higher spatial resolution (SD, HD, UHD). • Improved colour fidelity (High Dynamic Range). • Better motion depiction (Higher Frame Rate). Not to mention: • New content experiences (3D, 360° Video, AR, VR). • Next Generation Audio. All this keeps driving up our CDN distribution costs. Scalable media delivery on the Web with HTTP Server Push Cellular is biting at our heels • MNOs are hungry and have deep pockets. • 800 MHz band auctioned in 2013 for 4G. • 700 MHz band due to be auctioned soon for 5G. • 3GPP has developed a technology stack called MBMS for media streaming over cellular UHF Band V UHF Band VI radio networks. 470 MHz 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 854 MHz 2013 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 X X X X X X X X Our ability to innovate in 790 MHz 2020 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 X X X X X X X X X X X X X X X X X X X X 694 MHz 700 MHz Band auction 800 MHz Band auction the broadcast space is now hampered by lack of available spectrum. Scalable media delivery on the Web with HTTP Server Push The challenge • How to reach 98% of the UK population without any terrestrial spectrum. 10×audience To put that into perspective: • The last Royal Wedding 5×encoded bit rate (April 2011) attracted a total UK live audience of more than 25M across all = distribution modes. Even if CDNs could deliver to that size of audience, we probably couldn’t afford to 50×load pay for it. Scalable media delivery on the Web with HTTP Server Push Scalable media delivery on the Web with HTTP Server Push What about IP multicast? Media streaming over IP multicast • Layer 3 packet replication reduces redundant transfer. • Particularly well suited for large scale audiences. • A great way to address the scalability challenge. • IPTV is deployed around the world today and is supporting pay TV services. • Specified by DVB and published as ETSI TS 102 034. • Works well for managed networks / vertical deployments. • 3GPP also makes use of IP multicast for its Multicast/Broadcast Multimedia Service (MBMS). Scalable media delivery on the Web with HTTP Server Push Media streaming over HTTP • Industry has embraced unicast HTTP-based streaming. • Enables delivery over many types of access network (managed and unmanaged), to many types of end-user equipment. • This is the basis of myriad over-the-top (OTT) Internet streaming services including the BBC iPlayer. • Success driven by use of existing network technologies and Content Delivery Networks (CDN). Scalable media delivery on the Web with HTTP Server Push Adaptive media streaming over unicast HTTP • Divide media stream into short duration segments. • Each segment is encoded at several bit rates. • Client-side adaptation between these encodings, to suit local network conditions. • Graceful changes with respect to network degradation or improvement. • Several proprietary streaming technologies exist: • Microsoft Smooth Streaming. • Adobe HDS. • Apple HLS. • Industry aligning toward MPEG-DASH. Scalable media delivery on the Web with HTTP Server Push Standardisation of adaptive media streaming over IP multicast • CableLabs specification for ABR Multicast on CATV networks. • 3GPP MBMS specification for enhanced television (enTV) on cellular mobile networks. • DVB specification on adaptive media streaming over IP multicast. • Commercial requirements driven by use cases. • Technical work undertaken by TM-IPI ABR Multicast task force led by Richard Bradbury, BBC R&D. • DVB BlueBook A176, released March 2018. Scalable media delivery on the Web with HTTP Server Push DVB reference architecture for adaptive media • Abstract reference, functions and streaming over IP multicast interfaces. • Implementations may CP metrics RPM capture combine multiple functions in a single deployable unit. RCP RS Provisioning • Conventional unicast case CP Network C Control CP control • Unicast-to-multicast and CMR CMS Multicast App back again P ′ in gateway Multicast server M Content preparation Oin L • Maintains technical Pin U′ M compatibility with existing Content Content Playback playback control hosting Unicast A U reception equipment. repair A B Scalable media delivery on the Web with HTTP Server Push CP metrics RPM capture • The Multicast server ConversionRCP between multicast and unicast in the RS function converts from data plane Provisioning unicast (Oin) to multicast CP Network C Control CP control (M) at the sending end. CMR CMS • The Multicast gateway Multicast App Pin′ function performs the gateway Multicast server M inverse conversion from Content preparation Oin L Pin multicast back to unicast. U′ M • This is presented to the Content Content Playback playback control hosting Unicast A U Content playback repair A function via reference point L. B • This is a conventional MPEG-DASH player. Scalable media delivery on the Web with HTTP Server Push Deployment model 1: Multicast gateway • Terminal device supports deployed in terminal device reception of IP multicast • e.g. MBMS Client in mobile phone. Network Home Terminal device • Multicast gateway and edge gateway device device Content playback CMR functions all in the RS Multicast terminal device. L M gateway Content Playback • Relies on support for control App U playback multicast in the core A network. B Scalable media delivery on the Web with HTTP Server Push Deployment model 2: Multicast gateway • Multicast gateway located on Customer Premises deployed in home gateway device Equipment • e.g. home router supplied by the ISP. Network Home gateway device Terminal device edge device • Multicast gateway can CMR serve several users in the RS Multicast same home network. L M gateway Content Playback • Suited more to fixed line control App U playback deployments. A B Scalable media delivery on the Web with HTTP Server Push Deployment model 3: Multicast gateway • Multicast gateway deployed in a network deployed in network edge device edge device. • e.g. MEC server node. Network edge device Home Terminal device • Multicast gateway can gateway device serve several users in the CMR same network service RS Multicast area. L M gateway Content Playback • e.g. all mobiles within a control App U playback cluster of cell sites. A • Suitable when terminal B device cannot receive IP multicast. • All traffic on access network is unicast. Scalable media delivery on the Web with HTTP Server Push HTTP over multicast QUIC • An independent Internet Draft that fills some gaps between IP unicast and multicast. • Based on a new transport protocol called QUIC. • Describes a means of service discovery using HTTP Alternative Services [RFC 7838]. • Bulk file delivery that intentionally supports a broad range of Use Cases. https://datatracker.ietf.org/doc/draft-pardue-quic-http-mcast/ Scalable media delivery on the Web with HTTP Server Push Scalable media delivery on the Web with HTTP Server Push Server Push for unidirectional HTTP flows HTTP/2 • IETF RFC 7540 published in 2015. • Maintains existing HTTP semantics… HTTP • Request/response. • Metadata (Header fields) and payload.