TV News January 2018


Volume 5, Number 1

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-- Scott Johnson, Editor

It’s 2018. Don’t Forget the SMPTE.

SMPTE Illustration

The recently adopted SMPTE 2110-30 standard specifies that audio streams be in the AES67 format.

That is, audio output from your control room to the master control should be formatted for AES67 to be resynchronized with video. Re-synching audio to video is fairly straightforward because every packet in the AES67 audio stream carries a time stamp. AES67 is an IP audio multicast transport standard that uses the Precision Time Protocol IEEE 1588 as the master clock reference.

AES67 effectively eliminates the practice of HD/SDI audio embedding/de-embedding with video, and all the hardware that goes along with HD/SDI workflows.

It will take a while for stations to adopt the full SMPTE 2110 suite of standards, but broadcasters will need to keep SMPTE 2110 requirements in mind as they add new systems, specifically AES67 for audio.

Be sure to ask our systems and sales engineers what you can do now to prepare your IP audio infrastructure for SMPTE 2110. Call us at 252-638-7000 and ask to speak to Lon Neumann or Phil Owens.

IP Network Maintenance Tips

CHECKLISTHere are a few IP audio networking maintenance suggestions to start 2018 on a good note.

Cool it. Nothing kills electronic components faster than heat. Check the rack room to make sure the temp stays at a cool 70°F and check airflow around critical components. Consider installing heat and humidity sensors around critical gear, if you haven’t done so already. For every 18° above 70°, long-term electronic reliability can be reduced by roughly half (according to Uptime Institute).

If you have a WheatNet-IP audio network system, you can also use SNMP diagnostics to keep an eye on components and be on the alert for temperature and other changes. (More on that in a moment.)

If you discover a heat problem in the racks, you can try spacing out equipment with blank panels between them for better airflow. If things are really heating up, one temporary solution is to remove the ceiling tiles above the racks so heat can move farther up and away from equipment. A longer-term solution is to installed CRACs, or Computer Room Air Conditioners, in every third or fourth rack to cool things down.

Finally, consider upgrading fans and heat sinks in PCs and other gear, especially if you’ve upgraded to a new graphics card or processor, which could be generating additional heat as a result. In any case, you’ll want to routinely replace fans before the bearings begin to get noisy and cause issues.

Click to continue

Check network traffic. Bandwidth utilization in and out of Ethernet switch ports will vary from port to port, depending on the number of assigned channels (a typical stereo channel will use up 5 Mbps, including Ethernet audio overhead), but shouldn’t exceed port capacity. Use a program such as Cisco’s Network Assistant or other utility app to determine bandwidth utilization and overflow. If a particular port or switch is approaching overload, it might be time to add a new switch or reroute traffic to a different port or switch.

An IP scan of the network can be helpful as well, showing you which ports are in use and if something’s been added that shouldn’t be there.

For a more detailed account of network utilization, use the SNMP feature built into many network elements, including WheatNet-IP audio network I/O BLADEs. With third-party software such as SolarWinds or Nagios, you can capture packet counts, uptimes, temperature readings and other critical data for troubleshooting and monitoring network switches, BLADEs, PCs and other devices. WheatNet-IP also has debugging tools, which, when used with telnet applications such as PuTTY or Tera Term, can gather and analyze data based on how devices are receiving and sending commands.

Finally, we recommend that you use WheatNet-IP salvos to create a normalized set of routes for individual rooms, which can be helpful for quickly restoring routing if an issue arises.

Do a security check. Have you established employee levels of access based on job function, starting with the presets on your Wheatstone console? Is your network segmented into zones so if one studio goes down, it won’t affect your entire operation?

Consider grouping studios into separate segments, each with edge switches, and then connecting those segments to one central, redundant switch bank so if one part of the system is hacked into, the rest is isolated. If you have a WheatNet-IP audio network, you’re already one step ahead of the game. A great deal of redundancy exists in our I/O BLADE access units. Each BLADE has built in audio tools such as mixing for summing and mixing audio at any point in the network, plus will reconfigure itself in an emergency – and, in fact, can recover settings for your entire network.

Update Documentation. It’s a good idea to update any network routing and workflow documentation at this time, so you’ll have an accurate account showing the network topology as well as how the switches, I/O units, and servers are connected together. And, along with documentation, be sure to label all wiring and main infrastructure components so you know critical information such as which Ethernet wall-port or cable run goes to each port in the switch or panel.




Q: I see that your (WheatNet-IP audio network) system doesn’t provide for specifying low latency/high latency streams. Why is that?

A: A great question! All AoIP systems, regardless of manufacturer, have to deal with packet overhead. Because we are all using standard protocols, there is extra data that must accompany each "packet" of audio, allowing it to adhere to these standards. This is addressing, protocol, and timing information that all network switches depend on to route the packets to the right places. Since a standard IP packet can hold up to 1500 bytes of data, to stream audio on the network efficiently we all bundle or group a number of audio samples together in each packet, thus minimizing the percentage of data used for overhead. 

You can see that the more audio samples you place into each packet, the less packets you have to send and the lower the overhead becomes. In some systems, this is done because of limited bandwidth and processor resources, and the result is that those streams can have up to 100ms latency. Why does latency go up with larger packets? It's simple: it takes more time to assemble them because the audio data is being created at a set sample rate. You have to wait for enough audio samples to fill the packet. That wait means latency goes up.

The WheatNet-IP audio network does it differently. With gigabit links we have enough bandwidth to make every packet smaller and low latency. You're not forced into tradeoff choices, and there’s no need to spend any effort specifying packet depth per stream.

Wheatstone's Scott Johnson puts it like this: 

Say you have 100 pages to mail. You could put each one in its own envelope, but because the envelope is heavier than one page, you’ve more than doubled the weight. However, you can send each page as quickly as it comes off the printer.

Now if you put the 100 pages together in one big envelope you’ll have less overhead — 1 envelope vs. 100, your package weighs only slightly more than the pages themselves. But if you can only mail stuff in big envelopes 100 pages at a time, you’ve got to wait for 100 pages to be printed before you can seal and send the envelope.




Putting together a new studio? Updating an existing studio? 

We've put together this IP Audio for TV Production and Beyond e-book with fresh info and some of the articles that we've authored for our website, white papers, and news that dives into some of the cool stuff you can do with a modern AoIP network like Wheatstone's WheatNet-IP. And it's FREE to download!

Just click here or on the cover.

Wheatstone TV Consoles Video Tour

Phil Owens gives a tour of each of Wheatstone's TV audio consoles/control surfaces, explaining the differences between them to help give you a better idea of what you'll need to know.


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