How SMPTE 2110 Was Supposed to Replace SDI and Why It Hasn't Happened Yet

For many years, SDI (Serial Digital Interface) has been the standard for transmitting audio and video between professional devices such as cameras, mixers, and monitors. This technology, which evolved from analog times, is still in use today, providing high-quality 4K video transmission without compression and with minimal delay. Despite the emergence of new standards, SDI continues to play a key role in video production and broadcasting.

In recent years, however, SMPTE 2110, a standard for transmitting uncompressed video and audio over IP networks, has been introduced as an alternative to SDI, promising a more flexible, cost-effective, and scalable infrastructure. Yet, the transition from SDI to SMPTE 2110 has not been as smooth as expected.

What is SDI?

SDI is a standard that allows the transmission of uncompressed audio and video with minimal delay and in sync. It is used in film shooting, live broadcasts, and other tasks where synchronization of audio and video is critical. Video and audio signals can be transmitted through separate channels, and additional data such as teletext, advertising tags, and other metadata are also embedded. Simply put, SDI is a reliable and proven technology that continues to be used at various stages of the production process.

Why is SDI difficult to replace?

At first glance, SDI seems like the perfect solution. You plug the cable into the port, and everything works. Its ease of use and high reliability make it popular in studios around the world. However, SDI is a technology rooted in analog television, which brings with it several outdated solutions, such as the use of HANC and VANC.

HANC and VANC: what are they and why do they matter?

• HANC (Horizontal Ancillary Data) is the part of the signal where audio tracks are transmitted. This mechanism is used to synchronize audio and video in studio conditions. In modern SDI systems, HANC can transmit up to 16 channels of uncompressed audio, which is useful for multi-camera setups.

• VANC (Vertical Ancillary Data) is the area where subtitles, teletext, and other metadata, such as ad tags and program data, are transmitted. In early versions of SDI, this area was used for transmitting data in analog format, but modern systems use digital protocols, such as CEA-608/708 for subtitles.

Although these areas still have value in SDI, they increasingly face limitations when it comes to modern requirements for flexible data transmission. In the transition to IP, these data are transmitted in separate streams, providing more options for synchronization and management but complicating the setup process.

Main issues with SDI

• Outdated technologies: SDI continues to use structures like HANC and VANC, which were once necessary for analog television. Although they are still used, they can be inconvenient in modern digital systems.

• High cost of equipment: SDI capture cards cost between $450 and $5000, which is much more expensive than Ethernet equipment, which can be purchased for $45. This makes the system costly, especially for those starting out or planning to scale their infrastructure.

• Challenges with integration and reliability: Despite its apparent simplicity, SDI cards are not always stable in 24/7 broadcasting. For example, the popular Blackmagic Decklink cards may become unstable under heavy loads, making them unsuitable for continuous broadcasting.

SMPTE 2110: Future or Myth?

SMPTE 2110 promises to solve many of these issues by offering uncompressed video and audio transmission over IP networks. This means the possibility of using more affordable equipment and greater flexibility in managing data streams. For example, video and audio are transmitted in separate streams, which simplifies processing and improves synchronization.

However, SMPTE 2110 is not without its challenges. Here are some key issues:

• Cost and complexity of equipment: While moving to IP solutions can lower the cost of data transmission, the infrastructure for SMPTE 2110 still requires expensive equipment, such as network cards with PTP (Precision Time Protocol) support and specialized switches. Network cards compatible with SMPTE 2110 can cost over $1000.

• Lack of testing solutions: Unlike SDI, which can be tested with simple equipment, SMPTE 2110 lacks convenient test clients or tools for quick deployment. Code repositories and traffic dumps on GitHub remain fragmented and do not provide a comprehensive solution for developers.

• Synchronization issues: SMPTE 2110 uses the PTP protocol for time synchronization between sources, making the system more complex to set up. For example, there is no standard NTP support, and time synchronization accuracy becomes critical when working with multiple video and audio sources.

Why hasn’t SMPTE 2110 killed SDI yet?

Despite all the advantages of SMPTE 2110, its adoption remains challenging and expensive. For many studios and broadcasters, it is simply not cost-effective to switch to a new infrastructure, especially when SDI still performs its functions. Moreover, the software and equipment for SMPTE 2110 are still underdeveloped, making its implementation a risky and labor-intensive process.

Conclusion: Should we expect the end of SDI?

SDI is not going away and remains the main standard for many production and broadcasting companies. Its simplicity and reliability make it indispensable for many tasks. SMPTE 2110, on the other hand, offers a more flexible and potentially cheaper solution, but its complexity and the cost of equipment make it not the easiest choice for those looking for an immediate replacement for SDI.

IBC 2024 trends suggest that SDI is gradually fading into the background, but its final replacement by IP, particularly SMPTE 2110, still requires time.