How were store purchased, rented VHS tapes made?
This is a weird question, often wondered the answer.....
- How do studios produce so many copies of a VHS tape... - How do they record what is on the tape. - What are they usings for the source playblack.... Aka TV show, something shot on Film..... - What are they using for recording......what type of machine... - Do they make a master copy than go to mass production... - How would the encode the macrovision in the tape.. (granted Macrovision tends to degrade the quality of the picture big time) In house I have maybe 20 tapes of the same title. When u watch them, they are pretty much the same. They don't play that much different than the next. A store purchased VHS tape is normally a higher quality recording than something u record off the TV. |
The duplication is usually done with a bank of dedicated industrial duplicator VTRs. The tapes are fed in using automatic tape changers. Macrovision is likely encoded on the spot, the pro VTRs usually don't have any AGC circuitry which Macrovision targets. The source video is likely a high quality format like Betacam SP, and later on, any digital format. Wouldn't be surprised if 1" Type C reel to reel saw use in the 70s and 80s as well. The VHS tapes commercial recordings come on are usually lower quality though.
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Most production is -- or rather was, at this late date -- from a signal served by a non-VHS broadcast/duplication master. There's realtime methods, and non-realtime methods.
The Masters: Broadcast/dupe masters are typically U-matic (oldest), D-1, D-2, or Digital Betacam (Digibeta) versions of the edited film. It really wasn't until the DVD generation (2000s) that you had 2K and 4K film scans down-processed to DVD-Video specs via software, sometimes cleaned/filtered, and then encoded out to the MPEG-2 files. In other words, video output that's closer to the original sources. These days, D-1/D-2/Digibeta has been replaced by formats like MXF or DVCPRO50 (both of which I'm encoding from right now on the next machine over!). And then film itself has been supplanted by P2 and various 2K/4K formats. HD = 1920x1080p or 1280×720p 2K = 2048×1080p 4K = 4096×2160p Even Betacam SP is a rather low-budget grade of format, mostly used by news stations and indy studios. The lower budget modern alternate is HDV or DV (non-Pro). There were rival formats from Panasonic, such as D-3 and MII, too. (The "D-3" was sneaky marketing, as it was not an upgrade to D-2, but rather a different format entirely that competed with D-2. Reminds me of DVD-R vs DVD+R. It plays on social engineering.) Realtime: The realtime method was used by smaller post houses, cable/college facilities, etc. The master signal was then further processed to SD, genlocked and timebase corrected, within various processors -- often simply high grade multi-function TBCs. A distribution amp (or "splitter" to the layman) would feed the signal into racks of VTRs. VTR = video tape recorder, which isn't really the same as a VCR. A VTR lacks tuners, generally only recorded in SP mode, etc. Most of these were controlled by a central console of some kind. It was a turnkey system, but required human interaction to load/unload the tape decks, initiate the next batch, etc. Cheaper low-budget productions often used professional VCRs and recorded in LP or SLP/EP modes. These are the tapes from the dollar stores, flea markets, etc. Sadly, that is how quite a bit of animation was released in the 80s and early 90s, both licensed and public domain works. Only bootleggers used home consumer VCRs -- even the crappiest low budget operation used professional decks. I would note, however, that the low budget nature of the operation would generally abuse the machines, running them without cleaning or maintenance, and well beyond their expiration. Non-realtime: There are thermal-magnetic contact transfer systems that can create a tape in under a minute, with high speed processing. For example, Otari systems: http://www.otari.com/support/vintage/t710/index.html For this, a VHS master had to be created first -- likely on a special material. Several companies had patents on thermomagnetic contact duplication, such as Xerox and Dupont. The attached PDF is the Dupont patent. And then here's an article on the "new" technology, circa 1988: Attachment 1092 Who Made What? As far as who used what to make what ... I have no idea. I wouldn't be able to tell you which commercial video tapes were made with which method, and from which source. Given the rather sorry state of video industry record-keeping, I doubt anybody will remember which tapes were made with which methods, save a few retired or aging employees from dub facilities. I didn't really enter video until the end of the 1990s, as most of this technology was already dying and being replaced. My interest was heavily into digital restoration of older sources, and not the production of it. |
Here's a newsgroup post from earlier this year, with a first-hand account of the duplication business. It's sort of a quickie history lesson specifically about high-speed duplication of video tapes.
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This looks like it will also make for a good read...
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I just love this thread ! ! I always wondered how they did these tapes, because i have a couple ones (late 90's) that are pristine. Now I'm dreaming of a home TMD machine but i'm dreaming i know. They don't talk about cost but pretty sure it was in the 100-300k ballpark. Amazing tech
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What I don't understand is how HiFi audio is printed, It's recorded in a deep layer under the video, If the master contacting the blank tape it would only transfer the top layer which is video, Or do they have two masters one for audio and one for video and they repeat the process twice, But timing the audio to the video at a field level will be dificult.
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I agree that if they had to be done in two passes the time alignment would have been very difficult.
As I understand it, by definition low frequencies magnetize deeper into the oxide layer. The higher the high frequencies, the less they penetrate and the more they are confined to the surface layer of the oxide layer. So in the high speed duplication method described I assume all frequencies were effectively recorded in the same way as normal, with the lower frequencies going deeper and the higher frequencies shallower into the oxide layer. So it could all be accomplished in one pass, as with normal audio and video recording. |
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