IP networks for
video transport both
outside and inside the
studio, many existing,
are being phased out in
favor of products that
based on standards.
First introduced in 2007, the SMPTE
2022 standard has since expanded to cover
more types of IP video transport. The
first two sections of the standard cover
IP protocols for compressed, constant
bit-rate video signals in MPEG-2 transport
streams, based on COP3 from the Pro
MPEG Forum. Newer sections of the standard cover
two different kinds of variable-rate compressed
video signals, as well as methods
for carrying uncompressed video and hitless
protection switching. Each section of
2022 is described below.
ST 2022-1:2007 “Forward Error Correction
for Real-Time Video/Audio Transport
Over IP Networks” defines row/column
FEC (Forward Error Correction) for
IP video streams. Along with Section 2, this
standard has been widely implemented.
Row/Column FEC works by grouping IP
video packets into logical rows and columns,
and then appending one FEC packet
to each row and each column.
|Fig. 1: SMPTE 2022 interoperability tests conducted by the Video Services Forum
In the event that one packet is lost from
a row or a column, the data in that packet
can be perfectly recreated using the contents
of the FEC packet in conjunction
with the other packets in the row or column.
This method works quite well, and allows
the packet stream to survive lengthy
bursts of lost packets.
ST 2022-2:2007 “Unidirectional Transport
of Constant Bit Rate MPEG-2 Transport
Streams on IP Networks” specifies
how constant bit rate compressed video
signals that are encoded within MPEG-2
transport streams are encapsulated into IP
packets. This standard covers the transport
layer (RTP and UDP) as well as comments
about timing and buffer sizes.
ST 2022-3:2010 “Unidirectional Transport
of Variable Bit Rate MPEG-2 Transport
Streams on IP Networks” defines IP
packets for variable bit-rate MPEG-2 TS
streams that are constrained to have a
constant bit rate between PCR messages
ST 2022-4:2011 “Unidirectional Transport
of Non-Piecewise Constant Variable Bit
Rate MPEG-2 Streams on IP Networks” is
similar to Section 3, except that it removes
the constraint on bit rates.
ST 2022-5:2012 “Forward Error Correction
for High Bit Rate Media Transport
Over IP Networks” expands on Section 1
to allow larger row/column FEC combinations
to support signals with bit rates up
to 3 Gbps and beyond. A minor revision to
this standard is scheduled to be published
in 2013 by SMPTE.
ST 2022-6:2012 “Transport of High Bit
Rate Media Signals over IP Networks
(HBRMT)” specifies a way to transport
high bit-rate signals (including uncompressed
3 Gbps 1080p video) that are not
encapsulated in MPEG-2 transport streams.
2022-7 (approval pending) “Seamless Protection
Switching of SMPTE ST 2022 IP
Datagrams” describes a way to send two
matching streams of packets from a source
to a destination over different paths, and
have the receiver switch automatically between
them. This allows a perfect video
signal to be reconstructed at the receiver as
long as both paths do not fail simultaneously.
Another section originally called 2022-
8 was proposed to define a mapping for
JPEG2000 over MPEG-2TS over IP with
FEC. This capability appears to have been
fulfilled by the publication of VSF (Video
Services Forum, www.videoservicesforum.org)
Technical Recommendation TR-
01 “Transport of JPEG 2000 Broadcast Profile
Video in MPEG-2 TS over IP.”
The VSF has also arranged a number
of successful interoperability tests (“interops”)
to demonstrate that devices from
different manufacturers are able to send
and receive bit streams to one another. Fig.
1 shows a list of the interoperability tests
that have been performed to date.
2022 INSIDE THE STUDIO?
Work is currently underway in the Joint
Task Force on Networked Media to map
out a strategy for using packet-based networks
in the professional media industry.
This group, which held its first meeting
in March, is a cooperative effort between
SMPTE, the VSF and the European Broadcasting
Union. SMPTE 2022 may be considered
by the task force for encapsulating
uncompressed SDI and HD-SDI signals so
they can be transported over IP networks
within a studio, in place of baseband signals
over coaxial cables.
Other standards groups, such as IEEE
1722 Audio Video Transport Protocol, use
different methods for encapsulating SDI
video, one of which eliminates the RTP
headers found in 2022 and maps video
into Ethernet frames (packets). IEEE 1722
also dispenses with FEC (since packet loss
is very rare within local networks) and
groups all of the data associated with each
line of video into an integer number of
Ethernet frames, potentially making it easier
to build devices that perform switching
between video signals. Results from
the task force are expected to be ready in
As a wide-ranging standard for IP video,
SMPTE 2022 will certainly become more
important as IP technology continues to
penetrate the professional video production
Thanks to Carl Ostrom, Jack Douglass
and John Dale (all very active members
of the VSF) for providing information that
was used in writing this column.
Wes Simpson is an industry consultant
and author of “Video Over IP, Second Edition,”
from Focal Press. Your comments
are welcome to [email protected].