2021 Spring -SAI - unit 6 - IP TV PDF

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esta muy bien para practicar los conceptos basicos...

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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 April 2021

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.

Signalling of VoD services: RTSP

7.

IPTV diffusion architectures 7.1 Introduction 7.2 IPTV over managed networks: DVB-IP 7.3 OTT services 7.4 Advanced topics: CDNs, Hybrid TV (HbbTV), Adaptive streaming (DASH)

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

Unit 6 – IP TV

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0. Specific goals and evaluation •

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

•

To describe how video streams are formatted and multiplexed.

•

To introduce the different architectures for IPTV services.

•

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

•

To present Over-the-top services (OTT)

•

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

•

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

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

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End-to-end service

Scenario Digitization

Transmission storage Compressioncoding (lossless - lossy)

Protocols (Fragmentation, transport, signalling) Internet

Player Decoding decompression

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

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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

•

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

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

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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/

IP in Radio production •

•

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

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

–

Audio file exchanges

–

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

–

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

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

– – – –

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): Bidirectional communication with IP multicast, Opus codec http://www.panoramaaudiovisual.com/2017/03/31/la-xarxa-audiovisual-local-sustituye-el-satelite-por-redes-ip-en-distribucion-y-contribucion/

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

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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)

OB van SMPTE 2110 UHD https://www.panoramaaudiovisual.com/2019/01/22/tpc-suiza-unidad-movil-uhd-hdr-imagine-communications/

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...

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

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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

OB van SMPTE 2110 UHD https://www.panoramaaudiovisual.com/2019/01/22/tpc-suiza-unidad-movil-uhd-hdr-imagine-communications/

IP in TV production – Challenges to solve •

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

•

Containers: MXF (see next slides)

•

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

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Layer 2 Network: GigaEthernet, 10G/40G/100GigaEthernet – HD cams (1080i/720p) → 1.5 Gbit/s, 1080p → 3 Gbit/s, 4K → 12/24 Gbit/s

•

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

•

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

•

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 (short GoPs), 25-50 Mbit/s

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

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Professional codecs / formats – HD 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

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

4:2:2

50

4:2:2

30/40/50

Unit 6 – IP TV

PCM 24 bits/48KHz PCM 16 bits/48KHz 19

MXF: Media eXchange format •

XML-based container for professional audio/video files

Example of Header Partition

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TV3: example of IP in TV production •

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

•

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

•

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

•

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

•

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

•

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 and 28:20) http://www.tv3.cat/videos/4882851/TN-imatge-virtual-contingut-real

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

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

New technologies in TV production •

IP and transport layer protocols – SMPTE 2110: clock, video and audio transport over RTP – Transport of uncompressed video over RTP • RFC 4175 (not so new – separated RTP flows) • SMPTE 2022-6 (new, intermediate step between SDI and isolated RTP flows)

•

Layer 2 protocols: – Audio Video Bridging (AVB), later renamed as – Time-Sensitive Networking (TSN) • Basically, a time-slotted, prioritized Ethernet • Includes one profile of PTP

• Codecs – JPEG XS • Low-latency lightweight image codec (MJPEG!), lossy but visually lossless, for 4K and 8K video production signals” https:// Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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SMPTE 2110 •

New standard for TV production over IP, backed by SMPTE, EBU and vendors – Transport of uncompressed de video (or slightly compressed) – Transport of audio (usually uncompressed) – Synchronization – Network management, security, etc

•

Standard parts – ST 2110-10 - System architecture and synchronization (based on SMPTE 2059 - PTP) – ST 2110-20 - Uncompressed video transport, based on SMPTE 2022-6 and RFC 4175 – ST 2110-21 - Traffic shaping and network delivery timing – ST 2110-30 - Audio transport, based on AES67 – ST 2110-31 - Transport of AES3 formatted audio – ST 2110-40 - Transport of ancillary data Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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SMPTE 2110 - Synchronization •

Synchronization:

https://spectrum.ieee.org/consumer-electronics/audiovideo/smpte-st2110-structuring-the-future-of-broadcasting

– Global sync of all endpoints with PTP – Mapping of PTP time and RTP timestamps

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SMPTE 2110 – Video transport •

RTP possibilities: SMPTE 2022-6 or RFC 4175

RFC 4175

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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SMPTE 2110 – Audio transport • Audio: – Uncompressed Linear PCM Audio only – 48kHz sampling – 16 and 24 bits/sample – Audio per packet: variable, from 125 µs to 1ms – Channels in parallel: depends on the audio per packet • From 8 channels @ 1ms until 64 channels @ 125us

– Example: • 8 channels x 24 bits x 48,000 samples/s = 9,216 Mbit/s • Assuming 1 ms of audio per RTP packet: 9,216 Mbit/s x 1 ms = 1152 bytes of audio per RTP packet, 1000 packets/second (1 packet every 1 ms). • (1152 bytes audio + 40 bytes IP/UDP/RTP headers) x 1000 paq/s = 9,536 Mbits/s SMPTE ST 2110 – The Basics (Phil Myers) Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

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Transport of uncompressed video over RTP (Unit 2) •

Each video codec is linked with a specific RFC – In the case of uncompressed video: RFC 4175 and SMPTE 2022-6 – Some common aspects • Marker bit: 1 when the RTP packet carries the last fragment of a frame/field • All the RTP packets related to a frame carry the same timestamp • Time base of the timestamp clock is 90 Khz – Divisor of the 13.5 MHz clock used in SDI and 74.25 Mhz used in HD-SDI – Multiple of the typical frame rates (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  90 Khz / 59.94 frames/s = 1501/1502 RTP clock ticks (rounding)

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

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RFC 4175

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

– Protocol stack IP / UDP / RTP / RFC4175 / Payload (one or more video lines)

– Packetization/fragmentation rules • Only visible part of video • pgroup: minimum unfragmentable YUV group - See examples in the RFC

– General & specific RTP fields • 90 Khz timebase RTP timestamp - Multiple of 24 / 25 / 29.97 / 30 / 50 / 59.94 fps • Specific RTP header fields: extended sequence number, line offset, line 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 aka High-Bitrate Media Transport Protocol (HBRMT) – HBRMT specific header. Protocol stack: IP / UDP / RTP / HBRMT / Payload – Each IP packet contains 1376 bytes of SDI payload with the last packet of a frame being zero-padded to have each frame packet-aligned. – Includes active and not-active parts of the image (for 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 Serveis Audiovisuals sobre Internet (SAI) - EETAC – ENTEL - UPC

FRate: frame rate Unit 6 – IP TV

Sample; 4:2:2, 4:4:4, 4:2:0, etc 30

SMPTE 2022-6 formats

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Difference between RFC 4175 and SMPTE 2022-6

Video, audio and data embedded in a single RTP flow (SDI flow directly over IP)

(RFC 4175)

Each video, audio and flow is transported in a separate RTP flow

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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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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3. Challenges of TV & Radio diffusion over IP networks

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

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

Production (studios)

Diffusion

Other studios, external feeds

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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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

Unit 6 – IP...