smpte st 2022€¢ pt –payload type ... st 2022-1: forward error correction • xor packet...

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SMPTE ST 2022:Moving Serial Interfaces

(ASI & SDI) to IPThomas Edwards

VP Engineering & Development

FOX Networks Engineering & Operations

SMPTE Standards Update Webcasts

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Your Host

3

Joel E. Welch

Director of EducationSMPTE

Today’s Guest Speaker

Thomas Edwards

Vice President,

Engineering & Development

FOX Network Engineering & Operations



Overview

• ST 2022-x standards take payloads from specializedelectrical interfaces and puts them on IP using RTP

• The electrical interfaces are ASI and SDI

• The 2022-x standards are:

2022-1 Forward Error Correction for Real-Time Video/Audio Transport Over IP Networks

2022-2 Unidirectional Transport of Constant Bit Rate MPEG-2 Transport Streams on IP Networks

2022-3 Unidirectional Transport of Variable Bit Rate MPEG-2 Transport Streams on IP Networks

2022-4 Unidirectional Transport of Non-Piecewise Constant Variable Bit Rate MPEG-2 Streams on

IP Networks

2022-5 Forward Error Correction for Transport of High Bit Rate Media Signals over IP Networks (HBRMT)

2022-6 Transport of High Bit Rate Media Signals over IP Networks (HBRMT)

2022-7 Seamless Protection Switching of SMPTE ST 2022 IP Datagrams

MPEG Transport Stream (TS)

• ISO/IEC 13818-1 and ITU-T Rec. H.222.0

• Encapsulates packetized elementary streams (PES)

• Has error detection and stream synchronization

• 188 byte packets (or 204 with Reed-Solomon FEC)

• Every TS packet has a Payload ID (PID)

• Over 75 of mappings into MPEG TS• SMPTE Registration Authority, LLC is the registration authority for ISO/IEC

13818-1

• Besides MPEG video: KLV Data, Dolby Vision, Camera Positioning Information, VC-1, VC-4, Dirac, AES3, Dolby TrueHD audio…etc.



MPEG TS – Logical View

MPEG

Transport

Stream

0

PIDProgram Association Table (PAT)

Program # 100 – PMT PID 1025

Program # 200 – PMT PID 1026

Program Map Table (PMT)

Program # 100

Video PID – 501 – MPEG-2 Video

Audio PID (English) – 502 – MPEG-2 Audio

Audio PID (Spanish) – 503 – MPEG-2 Audio

Program Map Table (PMT)

Program # 200

Video PID – 601 – AVC Video

Audio PID (English) – 602 – AAC Audio

1025

501

502

503

1026

601

602

Video

Video

Audio 1

Audio

Audio 2

Program

100

Program

200

MPEG TS – Packet View

0x47(sync)

Flags PID(Payload ID)

More

Flags Data Payload

188 Bytes

CC Adaptation

Field

Flags:

• Transport Error Indicator

• Payload Unit Start Indicator

• Transport Priority

• Transport Scrambling Control

Important PIDs:

• 0x0000 – PAT PID

• 0x1FFF – “Null PID”

gives space for VBR

Continuity Counter (CC)

• 4-bit per-PID sequence #

• Helps detect packet loss

Adaptation Field (optional)

• Can carry range of other info

• PCR, splice point flags

• Transport of private data

PID

601

CC

11

PID

601

CC

12

PID

602

CC

7

PID

602

CC

8

Example Transport Stream Packet

Header

Example Transport Stream

PID0x1FFF

NULLPID

0

CC

3PAT

Data



Asynchronous Serial Interface (ASI)• Asynchronous -> no clock line, just self-clocked data

• European Standard EN 50083-9 Annex B

• Bottom layers Fibre Channel physical & signaling interface (FC-PH)

• Data transmission rate 270 Mbps on 75Ω coax or fiber

• 8-bit data converted to 10-bit for transmission for “DC-balance”

EN 50083-9:2002 - 28 -

Annex B (normative)

Asynchronous Serial Interface (ASI)

This annex describes a system for a serial, encoded transmission of different data rates with a constant transmission rate, based on a layered structure of MPEG Transport Packets according to EN ISO/IEC 13818-1 as a top layer (Layer-2), and a pair of bottom layers (Layer- 1 and Layer-0) based upon the Fibre Channel (FC) described in the ISO/IEC 14165-111 „Information technology - Fibre Channel - Part 111: Physical and signalling interface (FC-PH)“. Layer-1 and Layer-0 are based upon a subset of Fibre Channel Levels FC-1 and FC-0 . Transport Streams from different sources may have different data rates. The use of a constant transmission rate permits a constant receiver clock. To restore the original clock rate, a PLL circuit can be used. Annex E gives some proposals for how such a circuit can be designed. The input of the required transmission facility accepts MPEG-2 bytes and the output delivers MPEG-2 bytes. While the Fibre-Channel (FC) supports single mode fibre, multi-mode fibre, coaxial cable and twisted pair media interfaces, this standard defines only two distinct forms of interfaces: coaxial cable and multi-mode fibre-optical cable using LED emitters. Instead of a transmission rate of 265,625 Mbit/s, as required in the ISO/IEC standard, in this document the transmission rate is 270,000 Mbit/s.

B.1 ASI transmission system overview Figures B.1 and B.2 represent the primary components of the ASI transmission method over copper coaxial cable and fibre-optic cable, respectively.

Figure B.1 - Coaxial cable-based asynchronous serial transmission link (ASI type)

Sync Byte (FC Comma)

Insertion

Sync Byte (FC Comma)

Deletion

Clock/Data Recovery &

Serial/ParallelConversion

Coupling/ Impedance Matching

8B/10B Decoding

Amplifier/ Buffer

Connector

Parallel/SerialConversion

Coupling/ Impedance Matching

8B/10B Coding

Amplifier/ Buffer

Connector

Coaxial Cable

Packet-Synchronous MPEG2 TS

Packet- Synchronous MPEG-2 TS

Layer-1 Layer-0Layer-2 • Don’t have to use all 270 Mbps

• “Comma” 10-bit symbol inserted when no data ready to transmit

• Ignored by receivers

• Allows any bit rate <270 Mbps

IP – Internet Protocol

• A protocol for packet network intercommunication

• IP version 4 (IPv4) is dominant protocol of the Internet

• IPv6 its successor is starting to be used

IHL = Internet Header Length

TOS = Type of Service (now Differentiated Services Code Point, DSCP, and Explicit Congestion Notification, ECN)

If IP packet too large to fit downnetwork pipe, it gets “fragmented”

Identification: Groups fragments

Flags: Don’t Fragment /More Fragments

Address: 32 bits, human-readbleas A.B.C.D bytes

IPv4 Header



UDP – User Datagram Protocol

• RFC 768

• Connectionless datagram

• “Unreliable”, TCP/IP stack provides no packet loss detection or fix

• “Ports” for source & destination provide multiplexing of different applications and flows

• Header:

RTP – Real-time Transport Protocol

• RFC 3550

• Typically over UDP

• V – Version

• P – Padding at end

• X – Header Extension

• CC – #of CSRCs

• M – Marker bit

• PT – Payload Type

• Sequence # helps identify dropped packets

• Timestamp aids in sync

RTP Header

SSRC = Synchronization Source, the source of RTP

stream and timestamp

CSRC = Contributing Source, sources that have

contributed to a mixed stream (optional)Practically, 2022-x implementations use no CSRCs



ST 2022-2: Constant Bit Rate (CBR)TS over RTP

• References IETF RFC 2250

• Constrains RTP header fields:• Padding (P) bit = 0, Extension (X) bit = 0

• Payload Type: 33 (‘MP2T’)

• M bit: 0 (i.e. no timestamp discontinuities)

• Timestamp: 32-bit 90 KHz timestamp of target transmission time for 1st byteof payload

• Clock supposed synchronized with Program Clock Reference (PCR) or System Clock Reference (SCR)

• Which is not realistic for Multi-Program Transport Streams (MPTS) with multiple PCRs

• Either 1, 4, or 7 TS packets in RTP Payload

188 byte

TS packet

188 byte

TS packet

188 byte

TS packet

188 byte

TS packet

188 byte

TS packet

188 byte

TS packet

188 byte

TS packet

188 byte

TS packet

188 byte

TS packet

188 byte

TS packet

RTP

HDR

UDP

HDR

IP

HDR

188 byte

TS packet

188 byte

TS packet

Transport Stream

RTP Packet

ST 2022-2: Constant Bit Rate (CBR)TS over RTP

188 byte

TS packet

……



Basics of Parity FEC

• Forward Error Correction (FEC) sends redundant information toallow recovery from (some) data loss

• “Parity Operation” is mathematically exclusive-or (XOR)

• (A XOR B) XOR B = A & (A XOR B) XOR A = B

• Send A, B, and A XOR B – only need 2 to recover A & B

• Just XOR them to recover lost data – example below loses & recovers packet B

Packet A

Packet B

A XOR B

1 1 1 0 0 0 1

0 0 1 1 0 1 0

1 1 0 1 0 1 1

1 1 1 0 0 0 1

0 0 1 1 0 1 0

1 1 0 1 0 1 1

Packet A

Recovered

Packet B(A XOR B) XOR A

A XOR B

A B A XOR B

0 0 0

0 1 1

1 0 1

1 1 0

ST 2022-1: Forward Error Correction

• XOR packet payloads across L columns and D rows of RTP packets

• First FEC stream (columns) and second FEC’ stream (rows)



ST 2022-1: Forward Error Correction

• 2022-1 extends RFC 2733

• Media packets sent to destination UDP port N

• Level A devices: FEC stream (XOR down columns) on port N+2

• Level B devices: 2 FEC streams (XOR down columns &XOR across rows) on ports N+2, N+4

• FEC streams have own RTP sequence numbering

• FEC data uses payload type 96

Column and Row FEC Coverage

• First FEC stream (columns) handles burst losses up to length ‘L’

• Second FEC stream (rows) handles random losses

X X X

XX

X

X



ST 2022-1 FEC Header

• SNBase low bits: First sequence # of packets associated w. FEC packet (low 16 bits)

• Length, PT, and TS Recovery: XOR of packet lengths, Payload Types (PT), timestamps (TS) to enable recovery of these fields if missing packet

• E=1 indicating extended header, Mask not used, N=0, Type=0, Index=0

• D=0 for 1st (column) FEC stream, D=1 for 2nd (row) FEC stream

• Offset – offset between packets use for FEC: L for 1st FEC stream, 1 for 2nd FEC stream

• NA - # of packets associated w. FEC packet: D for 1st FEC stream, L for 2nd FEC stream

• SNBase ext bits – If needed, high 8 bits of first sequence # associated with FEC packetRTP sequence #’s are 16-bit, so should never be required

• Interleave media & FEC packets to avoid large TX rate changes

• Row FEC sent 0-L packets after last media packet protected

• Column FEC sent >L packets after last media packet protected (to avoid burst loss)

• Column FEC sent < LxD packets after last media packet protected (to constrain RX buffer)

ST 2022-1:2007 FEC traffic shaping issues



ST 2022-1 Block Aligned vs. Non-Block Aligned FEC

0 1 2

3 4 5

6 7 8

9 10 11

0 1 2

3 4 5

6 7 8

9 10 11

12 13 14

15 16 17

FEC

Pkt

SNBase

F1 0

F2 1

F3 2

• SNBase fields in header is first sequence number in FEC packet

• Non-block aligned FEC reduces TX buffer requirements for smooth FEC emission

FEC

Pkt

SNBase

F1 0

F2 4

F3 8

2022-1 FEC Latency Delay



ST 2022-3 Variable Bit Rate TS over RTP

• Real-time piecewise constant variable bit rate (VBR)

• Piecewise constant VBR means rate only changes at PCR-labeled packets of the program

• A max of 1, 4, or 7 TS packets per RTP packet per session (Packet_per_Datagram_max)

• Mode 1 – RTP packets always have Packet_per_Datagram_max TS packets. RTP packet send rate varies for VBR. Also has maximum_latency and maximum_bitrate.

• Mode 2 – RTP packets sent at constant rate, # of TS packets per RTP packet varies for VBR

ST 2220-3 Mode 1 vs. Mode 2

Mode 1

Mode 2



ST 2022-3 FEC Rules for Mode 1• Only block-aligned FEC

• maximum_latency limits FEC matrix latency, partially filled packets moved to next FEC matrix

ST 2022-3 Mode 1 FEC Header

• Like 2022-1 FEC header except…

• N=1 indicating ST 2022-3 Mode 1 FEC

• Maximum_latency - 10-bit number defining the multiplier of 10 ms (up to 10.24 seconds)

• Maximum_bit_rate - 10-bit number, first seven bits mantissa value and last 3 bits exponent value defining the multiplier of 10 Kbps (up to 1,280 Gbps)



ST 2022-4: Non-Piecewise Constant Variable Bit Rate TS

• Non-piecewise constant VBR when the bit rate varies between PCRs

• Timing would be clear in 270 Mbps ASI, but since IP networks are non-isochronous, timing relationship between TS packets lost in RTP transport

• 2022-4 signals inter-packet TS timing in RTP payload

• Number of TS packets per RTP packet shall not vary (i.e. always Packet_per_Datagram_max)

ST 2022-4 RTP Payload Structure

1,0 – Bits are set to 0b10 as a flag to signal end of TS packets (0x47=0b01000111)

TDD – Timing Data Descriptor, describes contents of Packet Timing Data Fields0b001 = running TS packet counter, 0b010 = 27 MHz clock

PTD # – Number of Packet Timing Data Fields in payload

In TS packet counter mode, null TS packets are discarded but noted in counter



SDI – Serial Digital Interface

• 75Ω coax or fiber

• ST 259 (“SD-SDI”)• Generally 270 Mbps, rarely 360 Mbps for widescreen

• SD-SDI is polarity insensitive, ASI is polarity sensitive

• ST 292-1 (“HD-SDI”)• “1.5 Gb/s”, actually 1.485 or 1.485/1.001 Gbps

• ST 425-1 (“3G-SDI”)• 2.97 or 2.97/1.001 Gbps

• Often used for 1080p50/60

• Can carry ST 291-1 Ancillary Data for Embedded Audio, CC, Timecode, etc.

HD-SDI Raster

Active Video

Horizontal

ANC space

(HANC)

Vertical ANC (VANC) space



HD-SDI ANC Space Data

Embedded Audio

Time Code

Closed

Captions

Line #

SAVEAV

ST 2022-6: SDI over RTP

• RTP items• Marker bit indicates last datagram in frame

• PT=98 for 2022-6, =99 for 2022-5 FEC

• 27 MHz RTP timestamp clock

• Video payload is always 1376 octets• One datagram often has data from two lines

• Sometimes a pixel or even a sample could be split between datagrams

• Last datagram in frame is padded with zeros to fill out 1376 octets



2022-6 Packet Boundaries for 720p

Note last packet

needs zero

padding to be

1376 octets

Example

packet

coverage

ST 2022-6 Payload Header

Ext – header extended by Ext x 4 octets

F – Is the video format present? 1=Yes

VSID – 0=primary, 1=protect

FRCount – Frame Count

R – Reference for video timestamp 0b00=not locked, 0b10=UTC, 0b11=private reference

S – Scrambling, 0=not scrambled

FEC – 0b000=none, 0b001=column, 0b010=row & column



ST 2022-6 Payload Header cont.

CF – Clock Frequency0000 = No time stamp

0001 = 27 MHz

0010 = 148.5 MHz

0011 = 148.5 /1.001 MHz

0100 = 297 MHz

0101 = 297/1.001MHz

MAP – 0=normal SDI or Level A, 1=Level B-DL,

2=Level B-DS

FRAME – Active picture size code

FRATE – Frame rate code

SAMPLE – Sampling type code (e.g. 0b01=4:2:2 10-bit)

Video Timestamp – At rate based on CF

Header Extension – TLV value (not defined to date)

2022-5 FEC for 2022-6

• 2022-5 defines row/column XOR FEC much like 2022-1

• Header similar to 2022-1 but slightly different…

• Added XORed recovery field for Padding (P), Extension (X), CSRC Count (CC), Marker Bit (M)

SMPTE ST 2022-5:2013

Page 11 of 22 pages

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

|E|R|P|X| CC |M| PT Recovery | SN Base |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| TS Recovery |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Length Recovery | Reserved |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Offset | Reserved | NA | Reserved |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 4 – Definition of the FEC Header

Extension flag (E) 1 bit:

The E bit is the extension flag reserved to indicate any future extension to this specification. It shall

be set to 0.

Reserved (R) 1 bit: Shall be set to zero by the sender. Padding Recovery field (P) 1 bit:

The Padding Recovery field shall be computed via the XOR operation applied to the corresponding P values from the RTP headers of the Media Datagrams Associated with the FEC Datagram.

Extension Recovery field (X) 1 bit: The Extension Recovery field shall be computed via the XOR operation applied to the corresponding X values from the RTP headers of the Media Datagrams Associated with the FEC Datagram.

CSRC Count Recovery field (CC) 4 bits: The CSRC Count Recovery field shall be computed via the XOR operation applied to the corresponding CC values from the RTP headers of the Media Datagrams Associated with the FEC Datagram.

Marker Recovery field (M) 1 bit: The Marker Recovery field shall be computed via the XOR operation applied to the corresponding M values from the RTP headers of the Media Datagrams Associated with the FEC Datagram.

Payload Type Recovery field (PT Recovery) 7 bits: The Payload Type Recovery field shall be computed via the XOR operation applied to the corresponding PT values from the RTP headers of the Media Datagrams Associated with the FEC Datagram.

Sequence Number Base (SN Base) 2 octets: The Sequence Number Base field shall be set to the lowest sequence number, taking wrap around into account, of those Media Datagrams protected by FEC.

Time Stamp Recovery (TS) 4 octets: The Time Stamp Recovery field shall be computed via the XOR operation applied to the timestamps of the Media Datagrams Associated with this FEC Datagram. This allows the timestamps to be completely recovered.

Length Recovery (LR) 2 octets: This field is used to determine the length of any recovered datagrams. The Length Recovery field shall be computed via the XOR operation applied to the unsigned network-ordered 16-bit

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10

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31

Dow

nlo

aded

at Fo

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8 fro

m IP



2022-6 Constraints on 2022-5 FEC

• L & D constraints• Column Only FEC

1 ≤ L ≤ 1020, 4 ≤ D ≤ 255• Column and Row FEC

4 ≤ L ≤ 1020, 4 ≤ D ≤ 255

• L x D constraints• SD (270 Mb/s) L x D ≤ 1500, max 33 ms protection

• HD (1.485 Mb/s) L x D ≤ 3000, max 6 ms protection

• 3G (2.97 Gb/s) L x D≤ 6000, max 3 ms protection

ST 2022-7: Seamless Protection Switching

• RTP packets replicated for transmission on multiple diverse paths

• Recoverable if at least one copy makes it through one path, within receiver buffer limitations



2022-7 Seamless Reconstruction Timing

Pn – instantaneous latency from TX to RX on path n inclusive of network jitter

EA – earliest time packet could reach RX for seamless reconstruction

PT – latency from TX to reconstructed output & latest time pkt can reach RX to be included in reconstructed output

MD – “max differential”, difference of PT and EA.

PD – instantaneous path differential,

Reconstruction possible from paths with Pn such that EA < Pn < PT

ST 2022-7: Receiver Classes

Receiver Classification Use Case (example) SBR Streams

< 270 Mbps

HBR Streams

> 270 Mbps

Class A: Low-Skew Intra-Facility Links PD <= 10ms PD <= 10ms

Class B: Moderate-Skew Short-Haul Links PD <= 50ms PD <= 50ms

Class C: High-Skew Long-Haul or special

circumstance Links

PD <= 450ms PD <= 150ms

(Proposed)

Class D: Ultra Low-Skew

Physical Layer LAN

Redundancy

PD <= 150µsec PD <= 150µsec



Using Wireshark for 2022-2Right-click “decode as” and choose “RTP”

Using Wireshark for 2022-6You’ll need a “dissector”:

https://github.com/FOXNEOAdvancedTechnology/smpte2022-6-dissector

https://github.com/FOXNEOAdvancedTechnology/smpte2022-6-dissector



Questions?

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