If you haven't yet checked out our May webcast, "IT for Engineers," you can access it here. The presentation was hosted by Al Kovalick and sponsored by Avocent. It was a great success and generated a lot of questions. Unfortunately, because of time constraints, Al couldn't answer all of your questions during the webcast, but you can find answers to those questions below. Also, if you have any additional questions about this webcast, go ahead and post them here!

Al also has a book called "Video Systems in an IT Environment," which is a great resource about this topic. You can find out more information about Al's book by going to the Web site www.theAVITbook.com.

Q: When will we have an all IT infrastructure for live events?

A: Ethernet switching providing time aware services are needed. For example the IEEE work from the Audio Video Bridging Group is a good start.See  http://ieee802.org/1/pages/avbridges.html. Other work is also being done to guarantee low delay and lossless frame switching for small networks. Remember too that cameras will need 1G or even 10G Ethernet ports. 

Q: Can I use the Internet to transfer large files, fast? 

A: Using WAFS on both ends of a transfer and Internet connectivity is very practical for large files. Study WAFS appliances from several companies. Also, see products from Aspera.

Q: You did not mention much on workflows. How does IT help me in creating better media workflows?

A: Good question. Workflows need to be agile to allow for changes and "quick" configurations as needed by business needs. Flows are about process orchestration, reliability, standards, API support for third-party services, data servers, storage and networking. These can all assist in creating agile AV flows. This is a huge topic and I can't do the answer justice with a short space.

Q: What about security? Can you recommend some best practices?

A: IPS is a key component. Most important is a policy on security for your company. This incldues VPN methods, patching, virus scan, firewalls -- I am sure you know all this. The AV difference is that real-time equipment can't be burdened with virus scans or on-demand patching. So always ask your vendor what his security processes are before you purchase. One method used by media companies is to quarantine all files that enter the facility and scan for viruses on an isolated server. Then, when it's been deemed clean, transfer to final destination.

Q: What's your opinion on implementing SOA/Web services in an end-to-end file-based workflow environment?

A: I am a big believer in the value of SOA for creating flexible workflows. The Advanced Media Workflow Association (www.amwa.tv) is one group that is looking at SOA integrated with media workflows.

Q: Did I miss an explanation of Metcalfe's Law?

A: No, I did not cover Metcalfe's Law. It is considered in the Video Systems book www.theAVITbook.com. Bottom line is that the power of a network is proportional to the number of connected nodes squared. The book explains why N^2 is present.

Q: Can u give an AV example of a hybrid stream/file solution that can provide "guaranteed" delivery?

A: The DSMCC method used by the satellite TV guys offers a data wheel for program guide data. As the wheel turns the receiver gathers the data files. If they are corrupt then the receiver can retrieve them on the next turn. The data files can be metadata or AV essence. Also I have seen streams of "files" sent to receivers (multicast) with strong FEC and a backchannel for requesting data not recoverable using FEC.

Q: So, who's going to develop these new IT-based A/V systems? Should we expect to see new solutions from traditional vendors, or will IT-centric companies develop A/V products?

A: Ethernet switching providing time-aware services are needed. For example the IEEE work from the Audio Video Bridging Group is a good start.See  http://ieee802.org/1/pages/avbridges.html. Other work is also being done to guarantee low delay and lossless frame switching for small networks. Remember too that cameras will need 1G or even 10G Ethernet ports.  I don't see the Cisco's of IT doing anything special for us. However there is sufficient need for time synchronous Ethernet for device control in precison manufactuing apps and for the telcos to create a MAC layer network to replace SONET. Both of these are usable to create frame accurate live video networks.

Q: Given compressed HD at 200Mb/s, how many concurrent seats can be supported in a 1G Ethernet?

A: I answered this one during the webinar. I concluded that 60 percent of the peak payload rate is typical for user data. 70 percent is a better value. With a well-designed network, the usable data value may be closer to 90 percent. There is overhead in the MAC/IP layers too. However, congestion is worse when every pipe is almost full so backing off decreases router and Ethernet switch delay.