Thursday, May 7, 2015

Camping Out on the Bridge - is HDBaseT Here to Stay?

Last week I appeared on the AV Powerup podcast to discuss, amongst other things, HDBaseT. Taking the time to listen to myself (this is a sign of responsibility to monitor messaging and personal branding, not at all vanity. Honestly) it seemed that I was quite negative on HDBaseT as a technology - I described it as largely a bridge between the point-to-point systems we build yesterday and the shiny new IP systems we'll be installing tomorrow. (You can hear the entire conversation, with Malissa Dillman of Kramer along Corey Moss and AVPowerup's usual cast of characters - here on rAVe Radio). After sounding what sounded like a death knell for HDBaseT I went to sleep and, the next day, went into the office to work on four projects, two of which will use HDBaseT transport. So... is HDBaseT here to stay? Is it a bridge we're crossing - or have already crossed? What's the place for it today?

Separate Networks and Separate Networks
If one is deploying video over IP, one needs to be careful to assure proper network configurations. This could mean QoS to prioritize latency-sensitive video traffic, IGMP settings for multi-cast streams, and other considerations. This will very often involve a logically separate network and, in some cases,  a physically separate network. A physically separate network consisting of structured cable, endpoints, and a dedicated switch for AV traffic sounds very much like the definition of an HDBaseT system. True, it isn't an IP-addressable system and, as such, there is no equivalent to "switch hops" within an IP-based system which allows a single logical network to be built with many switches. And yes, there is no "routing" equivalent allowing communication between networks. In the majority of AV use cases none of these are issues. In quite a few cases (including several of the projects on which I am now working), AV systems are largely self-contained and if they are to expand it will be via a higher-latency lower-bandwidth compressed signal such as H.264/H.265.

Why is IP the future?
That said I still firmly believe that IP is the future. Why?

First, scalability. It is very, very easy to add endpoints to an IP-based system. All one needs is an open switch-port or, at the very worst, another network switch. Expanding an HDBaseT system will often require shutting the system down to add input or output cards and, past "choke points" (8, 16, 32, 64), an entire system redesign. There's no good way to expand a full 16x16 switch, for example, without throwing it away and starting over again. IP-based systems are easy to grow and don't have the inherent size constraints that HDBaseT systems have.

On a related note, IP-based systems are flexible - not only because any IP video stream can be routed system-wide, but because it creates easy means of manipulating video streams. Adding a transcoder, a windowing processor, recording appliance, or anything else becomes a simple matter of connecting another network device. Manufacturers of network-based systems often create ecosystems including quite a few ways to manipulate the video stream.

There is a universality to using UTP for IP routable endpoints and only IP routable endpoints. One ends up with a single structuted-cable contractor for an entire job and no confusion with cables that look like network cables yet aren't. While this seems like a small issue, it does create an increase in efficiency in terms of both installation labor and infrastructure, as well as simplifying the physical system topography.

Why is HDBaseT Not Going Away
Even as IP is clearly the future and, increasingly, the present, I see new HDBaseT products appearing with some regularity. For AV systems which fit comfortably into a single HDBaseT switch there is a measure of simplicity in using dedicated, purpose-built AV switching hardware. Because we're dealing with a dedicated AV switch rather than a standard network switch, we can get local inputs and outputs for AV devices co-located with the AV switch. Eliminating the need for a transmitter or encoder at each device can, in systems with local sources, decrease overall wiring and count of individual devices.

The innards of an HDBaseT Wallplate
HDBaseT is also present in the "all-in-one" presentation systems which combine video routing, audio routing, audio amplification, and AV control in a single box. A system appropriate for a presentation switch such as this would usually be point-to-point, and gain little if any benefit from IP routing.

A big positive for HDBaseT is that it is a standard with a measure of interoperability; IP video transport is, at present, not. Yes, IP is standard, but different product lines do not allow their streams to be decoded by competitors. This means that, for example, a videowall processor with HDBaseT inputs can take a signal from an HDBaseT transmitter and then send it to HDBaseT embedded displays. An entire pair of transmitters and receivers just vanished! There's not yet the universality to do this yet with IP-based systems. I'm not sure when or if there will be.

So today, is IP better than HDBaseT? The answer is the same as the answer to every AV question:

It depends.

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