Don't just go IP - Go IT
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How you shouldn't just look at IP technologies in broadcast but also look at how off-the-shelf IT equipment can be used. Presented at NAB BEITC Engage! 2017
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Don't just go IP - Go IT
- 1. Don’t Just Go IP, Go IT! Kieran Kunhya – kierank@obe.tv @openbroadcastsy - #NABShow
- 2. What I’ll talk about today• IT in Live Broadcast Television (orders of magnitude differences for latency/bitrate compared to OTT). • History of IT in Live Broadcast • IP/IT Technical challenges • Using IT equipment in live broadcast
- 3. Who are we? • Central London based company • Build broadcast hardware and software using IT equipment • Written entirely in-house • Video contribution and general processing. • Involved in early multivendor IP deployments.
- 4. Traditional hardware architecture • Single or limited function cards with onboard FPGAs or DSPs doing majority of work. • Smaller CPU to perform control aspects.
- 5. A true software architecture Standard CPU performs all non- physical data processing ASI SDI MADI AES/EB U IP etc. ASI SDI MADI AES/EB U IP etc.
- 6. A true software architecture Standard CPU performs all non- physical data processing ASI SDI MADI AES/EB U IP etc. ASI SDI MADI AES/EB U IP etc.
- 7. Technological changes• Intel Nehalem (2008/09) • Realtime 1080i encoding • Only possible with overclocking before • Low cost SDI/ASI boards • Full 10-bit, VANC • Commodity hardware Everything available next-day!
- 8. Myth 1: IT hardware is too large and too power hungry Units reside in street furniture outside Downing Street, Buckingham Palace etc. Low depth (200mm) chassis, low power CPU. Encode/decode, ASI processing, Intercom.
- 9. Myth 2: IT hardware isn’t powerful enough And another 17 more cropped out! • Huge processing power available • 432 CPUs (small supercomputer) • Costs falling dramatically • Powerful enough for example to do high- bitrate VC-2 encoding/decoding, very high density H.264 decoding, ASI processing. • ~2-3x less rackspace for equivalent functionality compared to hardware • Processing power for new functions
- 10. Standards in software contextSMPTE 2022-6 – SDI over IP • Samples spanning packets (awkward) • Costly CRC • SDI frame tedious to construct TR-03 – separate RTP streams for video/audio • Samples no longer span packets (RFC4175) • Soon SMPTE 2110 • Will this actually be possible in software?
- 11. Pixel formats Only YUV 4:2:2 domain (as example)! • Planar 10b – main working format • Planar 8b - preview quality • UYVY 10b (16-bit aligned) – SDI datastream • Apple v210 – hardware • Contiguous 10-bit – 2022-6/TR-03 packing Tricky to work with in software.
- 12. Handwritten (no intrinsics!) SIMD for every mapping (and others). • 5-15x speed improvements compared to C • Do it once, make it fast once and for all (until new CPU…) • Generic conversion library a difficult problem • Intermediate pixel format(s) always a compromise • Add special cases until you’ve done them all! Pixel formats
- 14. One does not simply…Bypass the operating system DPDK, Netmap, Registered I/O A presentation in itself. See BBC R&D at UKNOF: https://www.youtube.com/watch?v=yL L8wl8YUwA
- 15. Kernel Bypass No network stack – You are the network stack • Craft Ethernet, IP, UDP headers yourself • No ARP, hardcoded MAC • Handle most of this in userspace • Lets you do pixel processing directly to/from Network Card memory.
- 16. Packet Spacing (1) THE million dollar question • Left unspecified in SMPTE 2022-6 • Hardware can do this with ~ns precision (measured with HFT equipment), but what about software?
- 17. Packet Spacing (2)• Varies by NIC vendor, measured two, both bimodal • Some implementations require “fake-packets” • More research needed! • Fractional Framerates 2.0 if constraints too tight
- 18. IT-based live production today • Dual-capable, SDI/ASI/AES and IP • Make it look the same to end-users, buttons, SNMP etc. • Incremental improvements like a web browser • Allow users to understand multifunctionality • Integrate seamlessly (e.g MPEG-TS)
- 19. IT-based live production tomorrow • A BIG COMPUTE RESOURCE • Live and offline on the same CPU • Remote kit can be processing low-priority batch jobs • Flash override on live broadcasts • Possible today but no orchestrator (microservices?) • FIMS too old (SOAP/XML…) • Control network and CPU resources
- 20. Decode MPEG-TS multicast Orchestrator goes and finds CPU resources somewhere, onsite or otherwise. Spin me up a multiviewer Transcode this file Not possible with SDI because SDI associated with a connector on a machine.
- 21. The V-word, Virtualisation• OS provides priorities to run multiple applications already • Many vendors on Windows (often without good reason) • Getting > 1Gbps of data out of VM nontrivial. • Live migration of complex, stateful broadcast applications not easy. (Not a web server…) • Complexity may outweigh benefits.
- 22. Using IT networks for contribution • Trend towards using generic, unmanaged, IP networks for broadcast contribution. • Regular in News (including cellular) • Growing use for Sport and Channel contribution • Important for any Cloud workflows (e.g Amazon Web Services) • Packet loss and Jitter (relative to traditional metrics) • Do it properly, using UDP. TCP not suited. • Variations on three main techniques.
- 23. Using IT networks for contribution (1)• SMPTE 2022-1/2 FEC • XOR based matrix (adds 2 * matrix latency) • Basic but wide support (albeit many broken implementations) Row FEC Column FEC
- 24. Using IT networks for contribution (2)• Retransmits (aka ARQ) • Receiver requests sender to transmit a copy of lost packet. • Affected by round-trip latency • Negative acknowledgment Sender Receive r
- 25. Using IT networks for contribution (3)• Dual-pathing (SMPTE 2022-7) • Hitless Switching Path1 Path2 Out
- 26. Example of IT and Generic IP at Scale• Deluxe Broadcast Delivery Network • Using software-based infrastructure for encoding, delivery and decoding. • Transported using multiple IP connections • Delivered NFL European Feed (inc SuperBowl) at 40Mbit/s
- 27. Example of IT and Generic IP at Scale (2)• Three nights of the One Show on BBC1 delivered using public internet (~5m viewers) • Reverse vision video on same unit. • Next step (in UK), long- form programming delivered over cellular?
- 28. Summary • IT equipment is on-air in the live broadcast chain today • The advent of IP-based production provides an opportunity to use multifunction IT equipment and gain massive flexibility. • Standards need to reflect this • The use of generic connectivity is increasing, and not just for financial reasons. • Going to be some very high-profile announcements in coming months
- 29. Q&A Find me on SL5624
Editor's Notes
- Feel free to ask difficult questions at the end. Tweeting is especially encouraged.
- Plenty of IT in OTT. Just because you write 1mbit/s OTT software, doesn’t make you qualified even to work with 10Mbps, let alone 100 or 1Gigabit. Building a road-car is not the same as building an F1 car. Hopefully something for everyone
- SpaceX are vertically integrated (metal comes in, rockets come out). Parts and software built in-house. Do things that commentators said was not possible. Homage in a lot of places
- Some manufacturers reflash fixed-function hardware on the fly. In a few cases the boards do a little more than just convert physical to digital. Exception that proves the rule. All of these things at the same time Note, no GPUs. I’ll address the V-word later.
- Could do trickery such as reuse of motion vectors Not an SDI frontend to an analogue chipset like some boards. Unthinkable a short time ago.
- I’d like to dispel some myths
- Pixels spanning packets makes things awkward RFC written by software people so doesn’t have this constraint.
- All of these pixel formats are specific to broadcast industry.
- That’s not a percentage sign, that’s a times. A big sudoku puzzle.
- Interop presentation, let’s look at technical reality
- People understanding that upgrading live broadcast chains weekly is not something to be afraid of. Just because PTP is a thing, doesn’t mean you should use it, or it will be available
- Used to be financial, starting to become flexibility above costs.
- Broadcast quality, 30-40Mbps, this isn’t Skype.