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Real Time Video Over IP

Real Time Video Over IP. Mapping and transporting video over IP networks Steve Hard Sales Engineer shard@nevion.com. Introduction. Transport of high quality real-time contribution video over IP networks

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Real Time Video Over IP

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  1. Real Time Video Over IP Mapping and transporting video over IP networks Steve Hard Sales Engineer shard@nevion.com Nevion Confidential

  2. Introduction • Transport of high quality real-time contribution video over IP networks • Goal is lower CAPEX and OPEX while maintaining quality and reliability and increasing flexibility • Discuss the challenges, trade-off and technologies to achieve this goal Nevion Confidential

  3. Moving from coax to IP video network Nevion Confidential

  4. Connectivity trends • Reliabilityof IP based services is improving • Bandwidthwillcontinue to increase • Price per Megabit is decreasing • Universal fibre coverage • Any-to-any services Nevion Confidential New opportunities for buildingcontribution video networks

  5. What is video over IP? • Many definitions: • Streaming video • IPTV • Primary distribution • Contribution • For broadcast professional video, it is • High quality video that is beyond the reach of the prosumer and consumer market • Not Streaming internet video like Youtube • Not “last mile” IPTV • Not IP as experienced in IT data networks contribution primary distribution sec. distribution Nevion Confidential

  6. Video over IP • Video over IP encompasses all video • In the Contribution and Primary Distribution space: • SD-SDI, HD-SDI, 3G-SDI • Uncompressed and Compressed Video • Unidirectional • Low latency • “Fire and Forget” • Need Forward Error Correction (FEC)? Nevion Confidential

  7. Who uses Professional Video over IP? • Anyone who has a need for scalable high quality video transport • Studios • Campus’s • Teleports • MSO’s • Telcos • Government agencies • Research Facilities • Telemedicine IP network Nevion Confidential

  8. Design factors • Is your system point-to-point or it is multicast? • Is there a back channel from the receiver to the transmitter? • Are the network connections relatively static or do they change often? • What level of control over the network do you have? Can you directly manage the network, or is it done with Service Level Agreements (SLAs)? • What is the error rate of the network? • What are bandwidth costs for the data and overhead that is required? Nevion Confidential

  9. Some commonly asked questions • Bandwidth • When you lease a circuit with a fixed bandwidth, you typically get the same rate in both directions • You can send video in both directions up to the limit of the service • Say you buy 100 Mbps • You can send video at 70 Mbps • You can also receive 70 Mbps of video on the same link Nevion Confidential

  10. Some commonly asked questions • Unicast • Video can be sent from one transmitter to one receiver. • There is only one video flow • Multicast • Video can be sent to multiple receivers • There is only one video flow from the transmitter • There are multiple flows to multiple receivers • Routers handle the request • Switches can to by using IGMP snooping Nevion Confidential

  11. Challenges of an IP network • Encapsulating The Video Data • Dealing With Packet Loss • Getting Video Across The Network • Protecting The Data • To Compress Or Not To Compress Nevion Confidential

  12. Encapsulating the video data • Challenges to solve • Break up video to get across network • Routing to get across network • Packet re-ordering • Detect packet corruption • Detect packet loss Nevion Confidential

  13. What are we trying to achieve? • Carry the video flow over IP packets: • MPEG packets into IP packets • Linear video into IP packets • J2K packets into IP packets • ....don’t forget the audio encode encapsulate transit decapsulate buffer decode Nevion Confidential

  14. Encapsulating the video data • 188 to 1376 bytes • Session Layer (5) • Transport Layer (4) • Network Layer 3 • Data Link Layer2 Video Signal RTP Video Signal UDP RTP Video Signal UDP RTP IP Video Signal Ethernet UDP RTP IP Video Signal Nevion Confidential

  15. Encapsulating using standards/protocols • SMPTE 2022 Family • Real-Time-Protocol (RTP) • User Datagram Protocol (UDP) • IP • Ethernet Nevion Confidential

  16. SMPTE 2022-xThe de facto standard for Video over IP Nevion Confidential

  17. Break up video to get across network • SMPTE 2022-2 • For MPEG-2 Transport Stream (TS) • 188 bytes TS packets • Up to 7 TS packets • Up to 1316 bytes (for 7 TS) • SMPTE 2022-6 • For uncompressed • 1376 bytes Nevion Confidential

  18. Why map via Transport Streams? • Widely used in all areas of video transport • Flexible formatting • Encapsulates data using well defined standards • Video : MPEG-2, H.264, JPEG 2000, Dirac … • Audio : MPEG-1/2, AAC, Dolby, AES … • Ancillary Data : Closed caption, aspect ratio, time code … • Data : IP/Ethernet, E1, T1, DS3, RS422, GPIO ... • Highly flexible • Multiplexing • Signal integrity monitoring • Protection switching • Encapsulates any data • ASI limit is 213Mbit/s, but TS over IP can run at higher speeds Nevion Confidential

  19. SMPTE 2022-2-2007 • Unidirectional transport of constant bit rate MPEG-2 transport streams (M2TS) over IP networks • Implies that video is compressed but can be anything • M2TS packets are packed into RTP/UDP/IP packets • RTP = Real Time Transport Protocol • Emphasis on real-time with error tolerance • UDP = User Datagram Protocol • Simple and connectionless (Fire and Forget) • IP = Internet Protocol • Suite of protocols for a variety of applications Ethernet MAC IP UDP RTP 1-7 TS or partial video line Nevion Confidential

  20. The Ethernet packet in transit Overhead: • 18 bytes for MAC • 20 bytes for IP • 8 bytes for UDP • 12 bytes for RTP • 28 bytes for FEC Ethernet MAC IP UDP RTP 1-7 TS or partial video line Payload: • 1 x TS packet = 188 (or 204) bytes • 7 x TS packets = 1316 bytes Nevion Confidential

  21. RTP header overview • 12 bytes of overhead on data payload Control Fields Sequence Number Timestamp SSRC identifier Data Nevion Confidential

  22. UDP header overview • 8 bytes of overhead on data payload UDP Source Port Number UDP Destination Port Number Message Length Checksum Data Nevion Confidential

  23. IP header overview • 20 bytes of overhead on data payload Control Fields Length Control Fields Control Fields Header Checksum Source IP Address Destination IP Address Data Nevion Confidential

  24. Ethernet Frame Overview • Start of Frame (SOF) • Preamble (01010101, seven times) • Start Frame Delimiter (10101011) • Cyclical Redundancy Check (CRC) • Validates that no bit has been changed accidentally • Also called Frame Check Sequence (FCS) SO F Ethernet Header Payload (Layer 3-7) CRC 8 bytes 4 bytes Nevion Confidential

  25. Ethernet Header • Every Ethernet card has a unique “burned-in” MAC address • First three bytes identify vendor, last three bytes are sequential • Destination address can be: • Physical address of one interface (unicast) • Network broadcast address (0xFFFF-FFFF-FFFF) • Multicast address SO F Ethernet Header Payload CRC 6 bytes 6 bytes Destination MAC Source MAC Some MAC prefixes 00:16:F6 Nevion (VPG) 00:22:3A Scientific Atlanta 00:00:0C Cisco Systems 00:25:9C Linksys 00:00:81 Nortel (Bay) 00:02:9c 3Com 00:01:30 Extreme Networks Nevion Confidential

  26. Ethernet Payload • IEEE 802.3 Ethernet precedes Info with 2-byte “EtherType” (a.k.a. Protocol Identifier) • Specifies format of corresponding data • EtherType is always > 1500 (decimal) SO F Ethernet Header Payload CRC Ether- Type Application Info Sample Ether-types 0x0800= IP 0x80D5= SNA 0x8137= IPX 0xAAAA = SNAP 2 bytes 46-1500 bytes Nevion Confidential

  27. Ethernet Frame Summary • Total frame size originally initially limited by CSMA/CD technology • 64 to 1518 bytes (without VLAN tag) • Excluding SOF • Allowable data size is 46-1500 bytes SO F Ethernet Header Payload CRC Ether- Type Application Info Destination MAC Source MAC 2 bytes 46-1500 bytes 4 bytes 6 bytes 6 bytes Frame Nevion Confidential

  28. Encapsulating the video data • 188 to 1376 bytes • Session Layer (5), Overhead 12 bytes or 0.9% • Transport Layer (4), Overhead 8 bytes or 0.6% • Layer 3, Overhead 20 bytes or 1.5% • Layer2, Overhead 42 bytes or 3.1% Video Signal RTP Video Signal UDP RTP Video Signal UDP RTP IP Video Signal Ethernet UDP RTP IP Video Signal Nevion Confidential

  29. SMPTE 2022-2-2007 • Other requirements of the standard • IGMP V2 : Multicasting • TOS/DSCP : For quality of service • Timing recovery • Also specifies limits on Forward Error Correction (FEC)(See SMPTE 2022-1-2007) Nevion Confidential

  30. Challenges of an IP network • Encapsulating The Video Data • Dealing With Packet Loss • Getting Video Across The Network • Protecting The Data • To Compress Or Not To Compress Nevion Confidential

  31. Packet Loss • Sources of packet loss • Congestion in the network • Random Noise • Cuts to links • Equipment failure • Dealing with packet loss • Detecting packet corruption • Detecting packet loss • Regenerating lost information Nevion Confidential

  32. Packet corruption/loss • Detecting • Ethernet and UDP have check field • Corruptions -> Loss packet • RTP has sequence number • Regeneration • Do nothing • Forward Error Correction (FEC) • Retransmit missing packets • Next generation IP solutions Nevion Confidential

  33. Forward Error Correction • SMPTE 2022-1 “Forward Error Correction for Real- Time Video/Audio Transport Over IP Networks” • For compressed TS • SMPTE 2022-5 “Forward Error Correction for High Bit Rate Media Transport over IP Networks” • For uncompressed Nevion Confidential

  34. Forward Error Correction • Video transmission via RTP/UDP/IP is best effort • Packets can get lost • One solution is to sent additional packets to aid in recovery • The problem becomes one of • Video input rate • Network Performance • Available Bandwidth • Desired packet recovery performance Nevion Confidential

  35. SMPTE 2022-1-2007 • Forward Error Correction for CBR MPEG-2 TS • Creation and transmission of redundant packets for correction • Error correction packets • transported via RTP/UDP/IP • created via XOR on RTP packets • FEC Streams sent on UDP • Port X+2 for Column FEC • Port X+4 for Row FEC • Where M2TS sent on UDP Port X Nevion Confidential

  36. SMPTE 2022-1-2007 : FEC Matrix • M2TS packets in the RTP payload are concatenated and ordered in a two dimensional array with LxD dimension. • Allowable range of values are: • L×D ≤ 100 • 1 ≤ L ≤ 20 • 4 ≤ D ≤ 20 Column, L (1,1) (2,1) (L,1) (1,2) (2,2) ROW, D (1,D) (L,D) Payload Nevion Confidential

  37. SMPTE 2022-1-2007 : Column FEC • Column FEC packets are calculated by XORing vertically. • In an L x D FEC matrix, there are L column FEC packets • Bandwidth requirement ranges from 5 to 25% Column, L (1,1) (2,1) (L,1) (1,2) (2,2) ROW, D (1,D) (L,D) 1 2 L Payload Column FEC Packet Nevion Confidential

  38. SMPTE 2022-1-2007 : Row and Column FEC • Row FEC packets are calculated by XORing Horizontally. • In an L x D FEC matrix, there are D row FEC packets • For Row and Column FEC, L ≥ 4 • Bandwidth requirement ranges from 20 to 50% Column, L 1 (1,1) (2,1) (L,1) (1,2) (2,2) ROW, D D (1,D) (L,D) 1 2 L Payload Column FEC Packet Row FEC Packet Nevion Confidential

  39. SMPTE 2022-1-2007 : Recoverable Packet Loss Lost Packet Nevion Confidential

  40. SMPTE 2022-1-2007 : Recoverable Packet Loss Lost Packet Nevion Confidential

  41. SMPTE 2022-1-2007 : Unrecoverable Packet Loss Lost Packet Nevion Confidential

  42. Transport - IP • FEC for IPLR attenuation generates significant overhead anywhere up to 50% • Question to ask is: “Is FEC a requirement in contribution networks?” • IP networks are usually carefully managed • If packets are being lost, then corrective action is required • FEC then is an insurance against the unknown Nevion Confidential

  43. FEC • Trade-offs • Overhead • Latency • Recovery ability • Design complexity -> Cost • Advantages • Lossy network • Multi-cast • No reverse channel available • Deterministic overhead Nevion Confidential

  44. Transport - IP • Bigger issue is network variances causing packet delay variation or packet jitter • Direct effect on timing recovery of the transport stream • Can be solved by buffering • However, buffering increases delay • Need to understand how jitter can be managed vs recovery of timing Nevion Confidential

  45. Retransmit missing packets • Advantages • Higher error recovery • Disadvantages • Requires reverse channel • Point-to-point connections • Variable overhead • High latency • No standards – Proprietary solutions Nevion Confidential

  46. Nevion’s SIPS technology:Next generation solution for redundancy • Streaming Intelligent Protection Switching (SIPS) • Fundamental building block for next generation managed video services • Slipless switching at IP layer • Does not affect services - no outages, no affection of downstream path • Works with multiple IP path configurations - dual and single • 1+1 edge equipment redundancy can be added to further increase availability • Common feature in the VS902/VS906 suite SIPS provides unparalleled service levels to broadcasters – even better than traditional video networks Nevion Confidential

  47. Nevion’s SIPS technologyNext generation solution for redundancy Nevion Confidential

  48. Video-layer service protection- Dual network interfaces SIPSTM Video in(ASI, SDI) Video out(ASI, SDI) • Protectionswitching done by Decoder • Sliplessswitching is provided by NevionsStreaming Intelligent ProtectionSwitching (SIPSTM) • Reduncancyprovided in case of: • Link failure in the core • Equipmentfailure in the core • Redundancyprovided by corerouters and switches • Link failurebetweenEncoder/Decoder and IP edgerouter • Noredundancyprovided in case of: • Encoder/Decoderequipmentfailure • Video source missing • Errors in video source signal Nevion Confidential

  49. Seamless Switching • Media is replicated and encapsulated over dual networks • Network routed over diverse path • Receivers buffers and time aligns packets from diverse network • Receiver selects best packet to provide error/glitch free switching Optimum Stream Look ahead switch Buffer Buffer Stream Analysis Nevion Confidential

  50. SIPS – pros and cons • Pros • Can be used for any media • Protects for the most common Link failures • Switch event is seamless (not detectable or measurable) • Protection capability is up and running with <1 second of link restoration and in the millisecond range on restoration of packet flows. • Cons • If diverse path is not guaranteed, Simultaneous loss of both feeds results in unrecoverable event. • Double bandwidth utilization • No protection for hardware failures Nevion Confidential

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