Connectivity – In the broadcast market, one of the key trends is the need to consider IP-based infrastructure solutions for routing of video and audio. The BNC-based SDI standard has dominated for years, but Ethernet centric solutions are gaining ground as there are no distance limitations and users can leverage the vast IT industry for equipment needs. FPGAs allow equipment makers to develop solutions more quickly than is possible with an ASIC, which is why they are often used in a variety of broadcast equipment.
To facilitate the transition from SDI-based distribution to IP-based distribution, SMPTE has ratified several standards and is in-process on others. The SMPTE 2022 standard was developed to help ensure interoperability for equipment designed to send AV over an Ethernet network. 2022-5/6 covers the encapsulation and transport of uncompressed 3G SDI signals (up to 3 GBps) over an IP Network (see bottom for full list of the seven parts of the standard).
But IP networks are notorious for losing packets as they travel for one end to the other. This can lead to glitches in the video, which is something most broadcasters cannot tolerate. To address this, SMPTE 2022 incorporates forward error correction (FEC) to help recover lost packets.
IP networks also have large latency variations, which require a means of synchronizing and switching between video streams. The IEEE1588 (Precision Time Protocol) allows for precise clock synchronization over local area networks (LANs) and wide area networks (WANs). A derivative of this protocol (SMPTE 2059) is used to generate clocks and time-stamps for remote video sources, and for those sources to be aligned and edited at a central location.
At IBC, Altera revealed its first-in-FPGA SMPTE 2059 solution integrated with a scalable SMPTE 2022 solution allowing for the precise synchronization and reliable transport of uncompressed or compressed A/V streams over an IP-enabled UHD infrastructure. The solution was developed in collaboration with Oregano and Macnica.
The demo is based on Altera’s new Generation 10 FPGAs. Currently, the Arria 10 is available for developers with the more powerful Stratix 10 to follow.
To learn more, check out this white paper from Oregamo. – Chris Chinnock
SMPTE STANDARDS 2022 (from Artel Video Systems White Paper)
When several manufacturers are all participating in a marketplace, industry standards help ensure that equipment from one supplier will be compatible with equipment from another. SMPTE 2022 plays that role for the video contribution market, by defining a number of standard methods for encapsulating compressed and uncompressed video in to IP packets. SMPTE 2022 currently consists of six parts, with a seventh due shortly:
Part 1 (ST 2022-1:2007) defines a row/column FEC (Forward Error Correction) method for real-time video streams carried over an IP network. In conjunction with Part 2, this standard has been widely implemented for compressed video transport.
Part 2 (ST 2022-2:2007) 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) and includes recommendations about timing and buffer sizes.
Part 3 (ST 2022-3:2010) and part 4 (ST 2022-4:2011) deal with two different types of variable bit rate MPEG-2 transport streams over IP networks. Although these standards have been finished for several years, there has not been a tremendous amount of commercial activity to develop products based on them. This could reflect the general difficulty in using variable bit rate streams for contribution applications, and the relative lack of interest in using these standards for delivering signals to consumers.
Part 5 (ST 2022-5:2012) and part 6 (ST 2022-6:2012) specify a way to transport high bit signals (including uncompressed 3 Gbps 1080p video) over IP networks, including an expanded form of row/column FEC. These newer parts the standard serve the same purpose as parts 1 and 2 for SDI and HD-SDI signals that are not encapsulated in MPEG2 transport streams.
Part 7 covers hitless protection switching, which is 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 simultaneously experience signal loss or packet failure. This configuration is typically reserved for extremely valuable signals, such as feeds from major international sporting events.
