Audio, IT/AV, Video

IPMX: Building An Open Standard For An AV-Over-IP Future

The IPMX set of standards and specifications brings a unique value proposition.

This article was written by David Chiappini and Andrew Starks on behalf of the Alliance for IP Media Solutions (AIMS) ProAV Working Group.

The first, but hopefully not final, AV trade show of this year—Integrated Systems Europe (ISE)—saw its usual rollout of new-product innovations, curious acquisitions and compelling partnerships. These common events are what continue to drive our industry forward.

As has been typical in recent years at ISE, a large percentage of the news addressed convergence with IT operations, as well as the ongoing transition to AV-over-IP systems. We expect that these themes will continue for years.

It’s not every year that the industry sees tangible forward momentum with potentially game-changing standards development. (Understandably, that process tends to move slowly through various standards bodies, tests and review procedures.) ISE 2020 stands apart, therefore, as the show that introduced the Internet Protocol Media Experience (IPMX)—a set of open standards and specifications to enable transport of video, audio and data over IP networks.

Developed by the Alliance for IP Media Solutions (AIMS) ProAV Working Group, IPMX implements a standards-based, SMPTE ST 2110-based approach with features and capabilities specific to commercial AV professionals, including manufacturers, AV integrators and consultants. Having the ability to carry compressed and uncompressed signals over varied networks (1Gb, 2.5Gb, 10Gb, 25Gb and even 100Gb) will address the interests and requirements of virtually anyone working in the AV industry, including technology managers that manage and operate end-user systems. IPMX also offers AV integrators features of specific interest, such as device discovery, registration and connection management, as well as specifications for copy protection and security.

Overall, IPMX’s introduction is intended to move the AV industry forward with a flexible and futureproof way to ensure interoperability for AV-over-IP products and systems, along with a framework for open, easy-to-deploy solutions for AV integrators.

The Scars To Prove It

The IPMX set of open standards and specifications was developed from battle-tested operations in the broadcast industry. It’s important to understand this for two reasons: First, the technical elements have been proven through an industry renowned for exacting demands, with input from high-end IP-transport and networking companies like Cisco, Arista and Mellanox. Second, the inherently gradual pace of standards review and approval—a well-rounded, democratic process that creates a trusted platform on which to build—is offset by the evidence of working products.

Trusted manufacturers, such as AJA Video Systems, Macnica, Matrox and Ross Video, introduced IPMX-compliant products at ISE 2020 that are proven and prepared to help fulfill the mission of AIMS and IPMX. In many cases, they will become competitive products that drive further innovation for users, as opposed to locking users into closed, proprietary solutions.

All that being said, broadcast and commercial AV represent two very different sets of customers and use cases. For example, IPMX will include a written specification for High-bandwidth Digital Content Protection (HDCP), a form of digital copy protection that requires transmitting devices to recognize if receivers are authorized to receive content before sending the data.

Unlike broadcast, which demands a stronger level of precision that requires master clocks and expensive, boundary-aware, Precision Time Protocol (PTP)-capable switches, the commercial AV market favors a simplified timing model with more manageable costs and technologies.

HDCP is a requirement for commercial AV both over baseband and over IP on local-area networks (LANs). The need to leverage, process and distribute protected content occurs very often in the commercial AV mission. An adaptation document is being discussed with the HDCP organization about how to use HDCP with ST 2110.

Similarly, today, commercial AV embraces compression, whereas broadcast has transitioned to more uncompressed models. IPMX, therefore, addresses a broader spectrum of transport networks that is agnostic to the underlying carriage layer. That requires intensive reviews and exposure to move highly compressed, lightly compressed and uncompressed signals over a variety of networks, all using the same standard and technology (as opposed to forcing customers to adapt to either 1Gb or 10Gb networks, for example). It also means confirming that performance-related requirements important to commercial AV—for example, very low latency and pristine visual quality—provide consistent, high-quality results, regardless of the level of compression.

Clean & Open

Many technical advantages have been built into the IPMX set of standards and specifications. These technologies are accompanied with the freedom for each user to make his or her own decisions, along with strong documentation to review in support of those choices.

For purposes of brevity, let’s look at the elements that are priorities for most commercial AV users. These important technical elements include clean switching, ultra-low latency, compression options, and device discovery and registration.

Many claim that clean switching is an attribute that exists within their products, although, in reality, the results vary in success. The desire for clean switching grew out of the AV industry’s reliance on the High-Definition Multimedia Interface (HDMI) matrix switcher. In these systems, the user adds baseband video and switches from one input to another; the transition would be “clean,” with no need to resynchronize, as long as the timing was close enough to monitor in real time. Historically, and even today, clean switching has not been considered mission-critical. However, the lack of synchronized presentation of source content in an expensive AV installation is certainly sufficient reason to want clean switching.

In the IPMX universe, clean switching represents a simplified timing mode that, when correctly implemented, provides a seamless experience upon transitioning from one IP stream to next. The clean switch eliminates onscreen glitching; an interruption that typically causes black is, instead, repaired at the transition boundary.

Normally, the greater the compression amount, the more challenging it is to achieve clean switching with lossless quality. However, IPMX’s inclusion of JPEG-XS’ frame-based compression means that streams can be tightly synchronized, with seamless, glitch-free presentation of audio and video on transitions. That does not mean that JPEG-XS is the only viable form of compression within IPMX, however. As AIMS is focused on open standards, IPMX can support multiple compression standards and algorithms, and at different bitrates. It is also well understood no one-size-fits-all compression solution exists.

JPEG-XS proved to be the ideal starting point for IPMX for several other reasons. Those included cost-efficient and flexible field-programmable gate array (FPGA) implementation, available software codecs, it being based on a true open standard (one little piece left to be approved later this year) and, as referenced earlier, ultra-low latency.

To the last point, IPMX supports sub-frame latency that is on par with the best and that’s unnoticeable to the human eye. Sub-frame latency is perfect for use in live events and medical environments, for example. Sub-frame latency is also a critical feature for keyboard, video and mouse (KVM) applications that benefit from high-quality compression and timing technologies, assuring minimal delay from source to destination.

Integrators Win

Beyond the more SMPTE ST 2110-driven benefits of hardware, transport and compression, IPMX also offers a genuine value proposition on the software side with its embrace of Network Media Open Specification (NMOS)—namely IS-04 and IS-05—standards. That software side includes an open RESTful API that is perhaps of special interest for AV integrators. IPMX is unique in offering a RESTful API as a base layer for integrated control and configuration, enabling device discovery and registration.

The underlying NMOS support is what allows users to control and manage the entire networked solution. Because this part of the system is open and interoperable, AV integrators have more creative power and control over the systems they design and integrate.

All of that, combined with flexibility across network architectures, compression bitrates and a single common programming language, plus other benefits, will give AV integrators virtually limitless freedom to customize AV-over-IP systems that optimize each end user’s experience. In the meantime, IPMX still has a roadmap ahead for testing, approval and refinement with standards bodies. However, the critical toolsets are established and ready to provide real value for the ongoing AV-over-IP transition.

Sound & Communications: May 2020 Digital Edition
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