2017 Spring -SAI - unit 6 - IP TV PDF

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Serveis Audiovisuals a Internet (SAI) Audiovisual Services on the Internet

Unit 6 – IP TV (production & diffusion) and Digital TV David Rincón Dept. Enginyeria Telemàtica May 2017

Contents 1.

Introduction

2.

IP networks in TV & Radio production

3.

Challenges of IP networks in TV diffusion

4.

MPEG Systems layer 4.1 Introduction 4.2 Program Stream 4.3 Transport Stream 4.4 DVB – Digital TV 4.5 H.264 Network Abstraction Layer

5.

Transport of video over RTP 5.1 MPEG-1/2 5.2 H.264

6.

IPTV diffusion architectures 6.1 Introduction 6.2 IPTV over managed networks: DVB-IP 6.3 OTT services 6.4 Advanced topics: CDNs, Hybrid TV (HbbTV), Adaptive streaming (DASH)

Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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0. Specific goals and evaluation •

To present how IP networks are being used in TV/Radio production and diffusion.

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To describe how video streams are formatted and multiplexed.

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To introduce the different architectures for IPTV services.

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To present DVB-IP as an integrated service architecture, covering several aspects: transport, protection, signalling, QoS...

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To present Over-the-top services (OTT)

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To introduce new, innovative services: CDN, DASH, HbbTV

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Evaluation: – Questionnaire – Lab session IPTV – Conference / demo / assignment (directed activities)

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End-to-end service

Scenario Digitization

Transmission storage Compressioncoding (lossless - lossy)

Protocols (Fragmentation, transport, signalling) Internet

Player Decoding decompression

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1. Introduction •

TV & Radio: the last frontier for IP networks – Context: convergence of services over IP – Easy for radio, difficult for TV (bandwidth – uncompressed and compressed) – Two scenarios: production and diffusion/broadcasting

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IP in production – Studios are nowadays completely digitized: workflow, processing, storage – Next step: substitute (video/audio) tapes & circuits by packet-switched LANs (Gbit/s) in studios and core/transport IP networks (between studios) • Cost, efficiency, operations, improved services (multicast of internal signals)

•

IP in diffusion – Broadband access networks: (xDSL, FTTx, 3G/4G/LTE): 10-300 Mbit/s – Next logical step: convergence to IP and substitution of the (expensive, inefficient) RF-based distribution and free it for mobile services • Cost, efficiency, new bidirectional / interactive services (podcast, VoD, multifeed…) Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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2. IP networks in TV & Radio production

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TV workflow: production & diffusion RF-based diffusion (DVB)

Production (studios)

Diffusion

Other studios, external feeds

TV3 studio control room

Shaw’s (Canada broadcaster) continuity control room (central playout)

2.1 IP in TV production • TV studios are migrating to IP-based communications – Video material exchanges (files) – Live video streams, internal consumption (beauty/traffic cams, external links, other TVs) – Live video streams, for live TV production – Feeds to broadcast: DVB-T (live TV via RF), IP CDNs (live TV, VoD) – Corporate IP services: e-mail, FTP, Internet access, IP telephony...

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SDI video “routers” vs IP network technology

“Packetized Professional Video”, Thomas Edwards, FOX Networks Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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Wikipedia: patch bay of a broadcasting van

IP in TV production – Challenges to solve •

Codecs: Different requirements, different codecs (see next slide)

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Containers: MXF (see next slides)

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Storage: High-performance, huge volumes, fast access (real time)

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Network: GigaEthernet, 10G/40G/100GigaEthernet – HD cams (1080i/720p) → 1.5 Gbit/s, 1080p → 3 Gbit/s, 4K → 12/24 Gbit/s

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Protocols – IP multicast, real-time issues (RTP), Quality of Service (QoS) – Working at Layer 2? Or at Layer 3?

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Security, Network management – to be discussed in other courses (SX, IOT)

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Clock: TV studios need to distribute highly precise master clocks – 27 MHz – 25/30/50/60 Hz. Recall the 90 Khz time base for RTP timestamps – NTP (Network Time Prot.) and PTP (Precision Time Prot.): ms/ns accuracy (see next slides) Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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Typical codecs/quality in TV production • Acquisition of the signal – Uncompressed, 4:2:2 signals, 10/12 bits/sample – HD-SDI → 1.5 Gbit/s. 1080p50/60 → 3 Gbit/s. – 4K and 8K, 12 bits:

Up to now: transport of SDI digital circuits over coaxial cable

• 3840x2160p50 → 9.95 Gbit/s, 7680x4320p100 → 79.6 Gbit/s

• Contribution, edition, postproduction – 4:2:2, compressed, MJPEG or MJPEG 2000 – Intra-only compression, High quality, 50 – 300 Mbit/s

• Long-term storage, pre-broadcast – 4:2:2 (maybe 4:2:0), compressed, MPEG-2 or H.264 – IPB compression, medium quality, 25-50 Mbit/s

• Broadcast / diffusion feeds – 4:2:0, compressed, MPEG-2 or H.264, low quality, 3-10 Mbit/s Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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Professional codecs / formats – SD quality Format

Container

Video codec

Chroma subsampling

Bitrate (Mbps)

Audio codec

1.5/3 Gbit/s

PCM

Acquisition SDI/HD-SDI

SDI

Uncompressed

4:2:2

Contribution / edition DVC ProHD

MXF

MJPEG

4:2:2

40/100

PCM 16 bits/48KHz

ProRes 422

MXF

MJPEG

4:2:2

100/142/220

PCM

ProRes 4444

MXF

MJPEG

4:4:4

330

PCM

DNxHD

MXF/MOV

MJPEG

4:2:2

36/145/220

PCM

Storage / Pre-broadcast XDCam HD422

MXF

XDCam IMX

MXF

MPEG-2 422P@HL MPEG-2 422P@ML

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4:2:2

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4:2:2

30/40/50

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PCM 24 bits/48KHz PCM 16 bits/48KHz 15

MXF: Media eXchange format •

XML-based container for professional audio/video files

Example of Header Partition

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TV3: example of IP networks INSIDE studios •

Layer 2: - network diagram – 10 GigaEthernet network at Sant Joan Despí, 4-10 Mbit/s links to delegations – QoS (priority queues, VPNs) – Girona delegation: 4 Mbit/s, shared with corporate. Live H.264 feeds prioritized

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Layer 3: OSPF + IP multicast PIM-SM + BGP – No QoS at layer 3

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Edition: MJPEG (DVCPro) at 50 Mbit/s (SD) or 150 Mbit/s (HD) – Edition at journalists PCs, rendered at servers. Not real-time.

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Internal distribution of other TVs, beauty cams, traffic cams... – H.264 at 2-4 Mbit/s, distributed internally via multicast PIM-SM – IGMP snooping at the switches: important for not flooding Ethernet segments

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Live video flows for production – Experimenting with HD-SDI at 1.5 Gbit/s and MJPEG at 100 Mbit/s

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Feeds to CDN (TV3 a la carta): – H.264 / H.263 at 1-2 Mbit/s

TV3 (2:20-3:20 and 21:24-22:53) http://www.tv3.cat/videos/4882851/TN-imatge-virtual-contingut-real

BBC Dirac (2:00-3:45) http://www.youtube.com/watch?v=HVFFq44UvLA

TV3 Conference at EETAC Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

http://www.youtube.com/watch?v=TG96UTMFmcs

Transport de vídeo sense comprimir sobre RTP • Com es transporta video sobre RTP? – Cada códec de vídeo defineix un RFC a mida – Pel cas de video sense comprimir: RFC 4175 i SMPTE 2022-6 – Alguns aspectes comuns • Marker bit: actiu quan es transporta l’última part útil d’una imatge • Timestamp referit a rellotge de 90 Khz – Divisor del mostreig a 27 MHz usat a SDI – Divisor del mostreig a 74.25 MHz usat a HD-SDI – Multiple dels frame rates habituals (24, 25, 29.97, etc)  90 Khz / 24 frames/s = 3750 RTP clock ticks  90 Khz / 25 frames/s = 3600 RTP clock ticks  90 Khz / 50 frames/s = 1800 RTP clock ticks  90 Khz / 29.97 frames/s = 3003 RTP clock ticks  90 Khz / 30 frames/s = 3000 RTP clock ticks  90 Khz / 60 frames/s = 1500 RTP clock ticks Serveis Audiovisuals sobre–Internet (SAI) - EETAC – ENTEL - UPC

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RFC 4175

https://tools.ietf.org/html/rfc4175

– Pila de protocols IP / UDP / RTP / RFC4175 / Payload

– Regles paquetització / fragmentació • Només es transporta la part visible de la imatge, línia a línia (fragmentades o agregades) • pgroup: grup minim de mostres YUV no fragmentables – Veure exemples a l’RFC

– Camps de la capçalera RTP general i específica • General: RTP timestamp referit a 90 KHz • Específica: extended sequence number, line offset, line number Reason for extending the Sequence number: “…for a 1-Gbps stream with 1000 octets packets, the standard RTP packet will roll over in 0.5 seconds, which can be a problem for detecting loss and out-of-order packets particularly in instances where the round-trip time is greater than half a second…” Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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SMPTE 2022-6 / High-Bitrate Media Transport Protocol – Pila de protocols: IP / UDP / RTP / HBRMT / Payload – Cada packet transporta exactament 1376 bytes de payload SDI • Últim paquet de la imatge amb farciment (zeros) si cal, per mantenir aliniament.

– Inclou parts visible (active) i no visible de la imatge (p.ex. embedded audio) http://sas-origin.onstreammedia.com/origin/smpte0109/SMPTE_Standards/2013_Standards_Webcasts/2013-06-11SMPTE_2022-Gilmer-Dale/2013-06-11-SMPTE_2022-Gilmer-Dale-handout.pdf

FRCount: frame number

CF: Clock frequency for video time stamp

Frame; Horizontal/Vertical, Progressive/Interlace

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FRate: frame rate

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Sample; 4:2:2, 4:4:4, 4:2:0, etc 20

SMPTE 2022-6 - formats

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SMPTE 2022-6 demo at EBU: 3840 x 2160, 60p, 10 bit, 4:2:2 → 9.95 Gbit/s

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Diferència entre RFC 4175 i SMPTE 2022-6

Image Source: http://www.tvtechnology.com/expertise/0003/new-standard-for-studio-video-over-ip-approved/277448 Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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Time–Sensitive Networking (TSN, 802.1 BA) •

New IEEE standard for real-time LANs

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Initially called AVB (Audio-Video Bridging), now TSN – “Ethernet for real-time signals audio and video” – Also applied to cars, aeronautics, and industrial communications! • BIG industry! Cameras, sensors… an Ethernet in your car, robots, airplane communications buses, industrial networks…

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Problems to solve – Timing and synchronization for time-sensitive applications: 802.1AS • Provide timestamps and distribute a common, high-accuracy clock • Similar to NTP, but much more stringent

– Stream reservation protocol: 802.1Qat • Reserved a path with guaranteed bandwidth and delay

– Forwarding and Queuing for Time-Sensitive Streams: 802.1Qav • Prioritization at queues. M/G/1 with priorities. • Traffic shaping with credit-based queues Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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TSN: Stream reservation protocol • “Talkers” broadcast BW reservation requests towards “listeners”

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TSN: Stream reservation protocol • Listener and switches confirm/deny reservation and advertise it BW reservation along the path

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TSN: Forwarding, queuing & traffic shaping

Token bucket !!

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TSN: Timing and synchronization • Audio and video are VERY sensitive to delays and jitter • Limitation of network diameter: up to 7 switches

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Precision Time Protocol (PTP – IEEE 1588) • Goal: synchronization of clocks through IP/LAN networks • Similar to NTP, with higher accuracy – In LANs, PTP reaches sub-microsecond accuracy

• Master clock corrects periodically slave clocks • 802.1AS is a profile of PTP • Transported directly over Ethernet, or IP/UDP • Messages – Sync:

to correct the offset between the clocks

– Follow Up: to measure the time Sync was sent – Delay Request / Delay Response: to measure the propagation delay http://en.wikipedia.org/wiki/Precision_Time_Protocol Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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Precision Time Protocol (PTP – IEEE 1588) • Example

http://www.ni.com/tutorial/2822/en/ Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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PTP Example • Sync • Follow up

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PTP Example • Delay Request

• Delay Response

IP TV

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Joint Team on Networked Media (JT-NM) • EBU + SMPTE + VSF joint effort for IP-based production

Examples of IP networks BETWEEN studios • Tele 5 (Mediaset Spain) IP/MPLS network – Externalized to Telefonica – 22 contribution points (delegations,studios,exchanges with other TVs) – MPLS mesh with dynamic tunnels • 10 simultaneous connections to the central node • Other connections not involving the central node can be established • Tunnel establishment time: 5 sec • QoS in the virtual circuits – prioritization of video

• Other examples of IP/MPLS core networks: Mediaset Italy, BBC UK (see PDF) • Near future: SDN networks & virtualization – You’ll see them in PX Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

BBC network (3:45-5:15) http://www.youtube.com/watch?v=HVFFq44UvLA Unit 6 – IP TV

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IP in Radio production •

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Radio studios have been digital and IP-based for years already! –

Corporate IP services: e-mail, FTP, Internet access, IP telephony...

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Audio file exchanges

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Live audio streams (external connections – over IP, ISDN or 3G/LTE)

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Feeds to broadcast: DAB, FM, IP CDNs (live radio, AoD - podcasts)

Things to solve: – Codecs: • FLAC / PCM for production/contribution, sometimes MPEG-Audio (MP2/3)

– – – –

Containers: WAV, MXF Storage: Not so stringent as TV – but still important Network: Not so stringent as TV – Gigabit Ethernet can be enough Protocols • Real-time, QoS. Working at Layer 2? Or at Layer 3?

– Security, Network management – Clock: master clock, but not as stringent as TV. NTP or IEEE 1588 (PTP) Example XAL (Diputació BCN): Bidiretcional, Opus codec http://www.panoramaaudiovisual.com/2017/03/31/la-xarxaaudiovisual-local-sustituye-el-satelite-por-redes-ip-en-distribucion-y-contribucion/

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VRT Belgium studio with Dalet Radio http://www.creativeplanetnetwork.com/the_wire/2012/09/04/vrt-selectsdalet-radio-suite-hd-for-radio-2-network/

3. Challenges of IP networks in TV & Radio diffusion

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Diffusion of IP TV • IPTV – Goal: to offer the same live TV as legacy RF-transported TV... – ... but also to provide advanced interactive services • Video on Demand (VoD) • Hybrid TV – integration of TV and Internet apps (web, social networks...)

– “Streaming” versus “IPTV” • A similar difference to that between “VoIP” versus “IP Telephony”

• Technical challenges – Codecs: highly compressed, lower quality (4:2:0): MPEG-2, H.264/AVC, H.265/HEVC – Transport: multiplexing (TS), multicast versus unicast, application level multicast (overlays), Content Delivery Networks (CDN). Protocols: RTP/UDP or TCP?

– Signalling: RTSP, SIP, IGMP, DVB-IP, HTTP – Protection: FEC (Forward Error Correction), parity, convolutional codes, interleaving – Conditional Access (encryption) Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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Diffusion of IP Radio • IP Radio – Goal: to offer the same live Radio as legacy AM and FM services.. – ... but also to provide audio on demand (podcast) • Audio on Demand (podcast) • Hybrid Radio – integration of Radio and Internet apps (web, social networks...)

• Technical challenges – Codecs: compressed, high quality (MPEG-Audio layer 2/3, AAC) – Transport: unicast over TCP, Content Delivery Networks (CDN) – even for live radio • Take a look at Shoutcast and CadenaSER.com as examples

– Signalling: usually HTTP delivered by CDNs – Protection: usually not an issue (TCP retransmissions + huge buffers) – Conditional Access usually not an issue

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4. MPEG Systems Layer

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4.1 Introduction to MPEG Systems •

The MPEG standards define: – Video

See http://mpeg.chiariglione.org/

– Audio – Other aspects (software, test, etc.) – System

•

The System Layer is responsible for: – Multiplexing (aud...