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Jun 1, 2009 12:00 PM
Thoughts from Broadcast Engineering’s readers
Video servers
Dear John Luff:
I've got two comments regarding your statement in the “Video servers” article in the May issue. You stated, “Servers were initially deployed to fix the inability of analog cart machines, based on analog video recorders, to play back-to-back 10-second spots.”
First, while the 10-second limitation was certainly true of the RCA TCR-100 2in quad cart machine, that was not the situation with the Ampex ACR-25. The ACR-25, also a 2in quad cart machine, could not only run back-to-back 10-second spots all day, but also you could run a 60in, a 30in and a 10in any order all day. In fact, a 60 could run, followed by a 10 and then followed by the same 60 again.
The ACR-25 was an incredible machine. It was the 2in quad cart version of the AVR-1, a 2in quad reel-to-reel beauty. The AVR-1 and the ACR-25 used vacuum columns for control of the tape. There were no idler arms and no capstan pinch roller. The AVR-1 shuttled tape at 500in per second and locked from a dead stop in 10ms. It was a roll and take machine. The same was true with the ACR-25: roll and take.
I believe that server deployment was caused by the need for a nontape-based playout system — no mechanical tape paths to worry about, no heads to wear out, no head clogs, etc.
I enjoyed the article, John!
Don Murray
Retired after 40 years in Miami TV
(35+ years at WTVJ, the NBC O&O)
John Luff responds:
You may be right about the ACR-25 and back-to-back 10s, but the context was actually Betacart- and Odetics Betacam-based hardware when servers first were employed. By that time, most quad spot delivery was gone, though not all.
I remember the AVR/ACR well. I was in the first Ampex AVR-1 training class in 1973. Taught by Jim Alford, the class was amazing! I had the first three production machines, which presented a “co-development opportunity.”
By the way, Ampex guaranteed five-frame lockup, about 150ms — though two to three frames was typical. Lockup in under one frame was not possible because it had to read at least one frame pulse to predict the tape position and correct it. Tape acceleration was about 500in/sec/sec, which made rewinding 10s pretty quick. If I remember correctly, when doing back-to-back 10s, it skipped rewind until time was available later.
More on servers
Dear John Luff:
You may recall we spoke recently at the Snell booth at NAB regarding the earliest video server. You earlier implied that the Tektronix PDR-100 was the first practical server, and I agreed.
I was in Malaysia in 1994 working to establish a new TV station, City Television in Kuala Lumpur for the Negeri Sembiulan Royal Family. It was to be fully component digital, and I was looking for a more suitable way to deliver the interstitial elements in conjunction with a VTR cart machine. At Asia Broadcast in 1994, Odetics demonstrated the TCS90 cart machine with a PDR-100 under Odetics automation. The PDR-100 was set up as a cache and would store up to about 50 minutes of “Betacam-quality” video.
I saw the unit again at IBC in September 1994, when we agreed to buy the setup. Odetics promised delivery at the end of 1994. Singapore Broadcasting Corporation placed an order before us but were not prepared to take delivery. So City TV Malaysia took the first unit from the factory at the end of 1994. Tektronix told me that the first PDR-100 was sold through Odetics as a cache. And Tektronix at that time confirmed with me that we took the first PDR-100 from the factory.
The interesting thing in the context of your May “Video servers” article is that the first PDR-100 with the TCS90 worked in conjunction with Panasonic D-5 machines. So the first PDR-100 had SMPTE-259C interfaces for video with analog audio. I required embedded audio, and to facilitate this, I employed Techniche (later acquired by Leitch) analog-to-SDI embedded interfaces so that the PDR-100, along with the D-5s, could record and playback embedded audio. This device was on-air by early February 1995.
I thought I should jot this down and send it off to you. Perhaps most servers were originally used in analog environments, but not the first!
Terry Harvey
Director of engineering and technology
WSIU Public Broadcasting
Southern Illinois University
Ergonomic workstation
Dear editor:
I was eager to look at the Field Report article in the May isssue on the new “ergonomic” workstations at Winsted. I was dismayed to see the photo from KENW-TV. How could a setup that includes those large flat panels mounted that high, that close to where a worker is seated ever be considered ergonomic? Let me state the obvious: Screens of that size are designed to be viewed from much farther back. I can tell you from my own unfortunate experience working with a similar setup that the result of such a setup is a very sore neck. Ergonomic? No way!
Maureen Crowe
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