Video

Considerations For Video Signal Management

High-quality video displays with the ability to show a variety of content from a wide range of sources play a crucial role in our day-to-day lives. Regardless of whether we enter a sports bar, house of worship, meeting room or lecture hall, high-quality video is not only increasingly prominent, but also expected. As a result, it’s more important than ever to have the ability to design and implement a video system with excellent image quality and the versatility to accommodate a variety of sources—frequently over considerable distances.

AV-over-IP, referring to the transmission of audiovisual data over a network, such as a local area network (LAN), wide area network (WAN) or the internet, is gaining increasing importance in this segment of the AV market. This approach facilitates the use of off-the-shelf products, while replacing traditional AV infrastructure. AV-over-IP solutions now compete directly with established technologies, and they are forcing the global matrix switcher market into a period of decline. In the commercial AV market, the replacement of traditional AV infrastructures with IP-based infrastructures is continuing to gain momentum. AV-over-IP is handled by decoders that package audiovisual data and transmit those packets over IP networks via Ethernet network switches. The decoder receives and unpacks the data packets to retrieve the audiovisual data.

The single most challenging issue for AV integrators has always been the growth limitation of the AV matrix switcher frame. Although larger and larger matrix switchers have become available from equipment manufacturers, the switching-requirement design remains restricted based on the number of inputs and outputs of the switcher frames present in the system. The most commonly encountered challenge occurs when the need arises to add another device to a maxed-out AV system.

By contrast, AV-over-IP enables integrators to connect as many encoders and decoders as the network design requires, while retaining the ability to expand further as requirements evolve. Based on the network configuration, integrators are also no longer limited by AV signals being confined within the room. The decoders on an AV-over-IP network can be configured to display any stream from any encoder. That arrangement facilitates single endpoint devices for smaller installations and a rackmount cluster for larger configurations. The decoders can be added to the switching design, as required.

For an effective AV-over-IP installation, two considerations are most important: (a) having an understanding of data packaging and compression, and (b) bandwidth. Some products on the market use industrial standards-based data-packaging and compression algorithms, whereas others use proprietary packaging and compression algorithms.

For the most part, standards-based data-packaging and compression algorithms deliver greater potential for interoperability between products from different vendors. Standards-based products generally have a roadmap and ecosystem capable of facilitating far greater infrastructure-migration benefits than anything based on a single supplier.

The H.264/H.265 and JPEG2000 protocols are very commonly used industrial standard data-packaging and -compression algorithms. Similarly, SDVoE, which is focused on video quality and image-processing capability, is another standard that is experiencing greater adoption in the commercial AV market. SDVoE supports both upscaling and downscaling for resolutions up to true 4K/60/4:4:4, with almost no latency (just ~30μs of latency at 4K/60Hz)—however, it requires a 10Gb Ethernet switch.

Another important consideration when implementing AV-over-IP is bandwidth. It is important to ensure the IP network satisfies the requirements presented by the AV traffic. A raw 1080p 60fps stream with 24-bit color requires 1920x1080x60x24 = ~3Gb/s. A 4K signal with the same parameters requires ~12Gb/s. A single stream with compression can be readily conveyed by an ordinary gigabit switch. Multiple streams can be simultaneously delivered from multiple sources to multiple displays through a single switch—assuming the switch is properly equipped and configured. These streams can be delivered via TCP/IP unicast or UDP/IP multicast. If UDP/IP multicast is used, then the Internet Group Management Protocol (IGMP) functions of the switch must be properly configured. If IGMP is not configured properly, then each stream can potentially end up being delivered to all ports; that would result in an overburdened network that would be incapable of properly delivering the streams.

If an application requires high-quality video with minimal latency—think about healthcare and government applications—then a 10Gb network is much better. But bear in mind tradeoffs exist between video quality and bandwidth that must be considered when reviewing quality requirements and existing IP network infrastructure.

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