How does Macrovision signal get onto a VHS tape to start with?

[Videogamer555]

I know that that once on a tape, it can't be copied by VCR, so the production company takes a master tape, and makes multiple copies with a tape-to-tape copier (where the physical tape from the source tape is pressed up against the physical tape of the destination tape, and magnetically transferred), but how does that Macrovision anticopy signal get put onto the master tape to start with? Does the professional movie camera with which movie was filmed (and thus which the initial master tape is generated) have its own builtin Macrovision inserter circuit within the camera? If not, how exactly does the Macrovision signal get put onto the tape? I've tried looking on eBay for Macrovision inserter devices (the theoretical devices that movie production companies would use to insert the Macrovision signal onto the master tape), hoping that maybe some small and now defunct movie company would have sold off their assets on eBay, including their Macrovision inserter, but I have NEVER found any for sale. And Googling things like "Macrovision inserter" only gets me search results for Macrovision REMOVERS (which are of course illegal), as it seems the only Macrovision related device anybody else is interested in (and thus searches for) are the removers. And as Google is analytics/algorithm driven, it detects the most common search queries, and then any similar search queries (even if DIFFERENT from the most common ones) give the results for the most common queries, depriving me of the information I'm ACTUALLY looking for. So Google has been no help to me. So all my searches for Macrovision inserters, give me results for Macrovision removers. This is VERY frustrating (I don't think there's any search engine anymore that actually gives you results for what you actually typed in your search query, only what its algorithm thinks you meant to type in the search query).

Sorry for the side rant about search engines. But my main question remains. How do movie production companies actually insert the Macrovision signal into their master tapes?

[betwixt]

It isn't on the master tape. Macrovision is inserted in the blanking period, part of the video waveform you don't normally see. By using suitable electronics it is possible to insert it in the path between master and copies. It doesn't actually add anything to the viewable part of the recording, it adds a varying additional signal in the blanking period that upsets the automatic level control when played back. REMOVERS do just that, they substitute a clean blanking signal for the one they see on the tape so the macrovison protection is missing from then on.

Brian.

[cholla]

@ betwixt,
Best explanation I've read.

@Videogamer555,
In the USA the Fair use act makes it legal to remove Macrovision for personal use.

The Digital Millennium Copyright Act (DMCA) makes it illegal to manufacture or sell devices specifically designed to circumvent Macrovision

Which is not exactly the truth. A VCR removes the Macrovision when played or you would see it.
So a VCR which is a device that circumvents Macrovision.
A VCR just won't output to an external recording device without the Macrovision signal.

[aramkolt]

Not 100% sure, but I've read that large commercial runs of tapes aren't made in VCRs, basically the magnetic information is on very long strips of magnetic material and then the tape gets placed over it for a few seconds to transfer the information of an entire film all at once, or possibly by being rolled against the magnetic master, then the tape gets wound onto the reels and encased, so the macrovision would already be on the magnetic master. I don't think there's actually any heterodyned recording of tape like you'd get in a realtime recording. Oddly, I haven't seen any YouTube videos that actually show commercial VHS tape production.

Macrovision is really just some information in the vertical blanking area and usually consumer VCRs don't record there even if you attempt to copy a tape that already has it, but I could be wrong about that since I haven't tried it. The main way that macrovision messes with the copy is by tricking automatic gain controls into thinking there are certain parts of the frame that are very bright or very dark, so the rest of the brightness values in the main image get scaled up or down to keep the full displayed range legal when making a recording. If you had a way to disable automatic gain control for recording, macrovision wouldn't work at all for the intended purpose anyway.

VCRs don't actually circumvent the macrovision on playback, they send it along with the composite output signal during playback, it's the display device that ignores it mainly because it's outside of the displayed area. Display devices typically don't have automatic gain control to get confused by it. Most capture cards also don't capture the area to get confused by macrovision either, but they can recognize that it is present and decide to allow capture or not.

Macrovision was also a patented technology that you'd have to license per film I believe, so I don't think there are VCRs that will just insert macrovision during recording.

[betwixt]

Commercial tapes are made in VCRs but not ones you would use domestically. 'Contact printing' is very unlikely to work, firstly it would reduce the magnetism on the master very quickly and secondly it would require very intimate contact and possibly for a relatively long time. I'm not sure what the machinery looks like, possibly the tape is recorded before being loaded into the housing, it would certainly be quicker if the recording and packaging could be carried out as parallel operations.

I have designed audio cassette duplicators but they don't stretch the technology as far. Playing the master and the slave at high speed to reduce time means the frequency spectrum to the heads is also increased. For audio, frequencies beyond 200KHz were recorded but for video that would equate to around 45MHz which is beyond the capability of a normal recording head. One of the problems I had with audio duplicator was a whistle on the recorded tape caused by AM radio station signals breaking into the amplifiers, when slowed down to normal speed the carrier frequencies dropped inside the audible range.

Brian.

[lingyi]

Early duplication was by banks of VCRs, possibly dedicated recorder only. Later production used contact printers from Sony or Otari.

https://www.digitrakcom.com/TechDocs/SONYsprinter.pdf
https://www.otari.com/support/vintage/t710/index.html
http://www.otari.co.jp/support/vintage/r750/index.html

Edit: Because large commercial contact printed tape was custom cut and spooled into the cassettes, it was (nearly) exactly the length needed for the release. Smaller companies did use preloaded cassettes, which which is why non-standard duplicator blanks such as T-105 (for VHS) and L-625 videcassettes were sometimes available on the consumer market. One of my most prided treasures from my former Betaphile days was a 10 tape case of retail case Fuji L-125 cassettes!

Edit 2: Because contact printers cost 5-6+(?) figures and reportedly very high maintenance, most distributors properly had duplication houses create their products.

[lingyi]

In VHS, alterations to the analog video signal are added in a Macrovision-provided "processor box" used by duplicators.
https://en.wikipedia.org/wiki/Analog_Protection_System
https://en.wikipedia.org/wiki/TiVo_Corporation
https://cs.stanford.edu/people/eroberts/cs181/projects/1999-00/dmca-2k/macrovision.html

Before Macrovision, there was Copyguard, which was discontinued because it reportedly caused issues even when videos were viewed directly on some TVs. I believe there were other copy protection schemes other than Copyguard in the early days of prerecorded tapes, but I can't recall the names.

As stated, Macrovision required a per video license and affected the AGC as it varied from light to dark.

On CRTs that had vertical hold adjustment, you could see the VBI and watch the blocks change from bright white to dark.
https://github.com/fsphil/hacktv/issues/44

Because it affected the AGC on the VCR, it affected some makes/models more than others and because the way Beta implemented AGC, some, but not all Betamax(s) were unaffected. I could copy a Macrovision video, but if I tried to make a copy of the copy, even Beta to Beta, the Macrovision came back. And one some tapes, the strobe effect was still there, but very slow and barely noticiable.

Macrovision black boxes worked by stabilizing, but not removing the strobing, and there were multiple revisions of Macrovision over the years, which is why later boxes didn't always work. Only a TBC (I had a TBC-1000) would completely strip and rebuild the VBI, removing the Macrovision.

Trivia. Before Macrovision

[lingyi]

I believe all copy protection schemes, Macrovision, CCS, AACS are applied to masters only by select production houses because of the licensing requirement.*

*This is why, even today, most non U.S. optical disc releases don't have any type of copy protection. I've copied hundreds of Asian videotapes (in the 80's - early 2000's) and never encountered any type of copy protection if the release was from a non-U.S. distributor.

[aramkolt]

Not exactly related to the original post, but since it is a macrovision discussion, there was at least one series of VCR that would remove macrovision without external equipment and that'd be some of the BR-S series like the 822, 622, 522, 525 with the TBC option. It had some internal DIP switches that would blank some or all of the VBI depending on how they were set.

I'd be curious if anyone else knows about other VCR models that can remove macrovision during playback without external equipment.

[lingyi]

Here's a good thread about how Macrovision was applied to videotapes, black boxes and TBCs.

https://forum.videohelp.com/threads/396464-Macrovision-question

Edit: Cornucopia worked in a duplication house and explains why you don't see Macrovision boxes aren't widely available here:

Macrovision - it was a very simple 1U box, stuck in the top corner of the racks - because there were barely any controls to it and it was left on constantly. It was Macrovision-branded. It had genlock, input and output jacks, and that's it. It was a pass-through injector device that modified whatever ran through it. It included all of the multiple MV methodologies. It would have been setup in a run to be the last device in the patch chain prior to the distribution amp feed, when swtiched in (which was always a checkbox option for the producers, if they were willing to pay the additional licensing fees to use it - 80% of them did). No conspiracies, just corporate greed-originated IP protectionism, which many voluntarily jumped on the bandwagon. My understanding is that those boxes were never bought, but were LEASED from Macrovision. Thus if they were ever ending a contract, or if the dupe house ended business, had a fire, or anything else, the machine would have to be delivered back to MV. Which is why you don't see any out in the wild now.

[pandy]

As stated, Macrovision required a per video license and affected the AGC as it varied from light to dark.

Depends on Macrovision rev - at the final years Macrovision efficiently address: AGC, synchronization and at some point they introduced split chroma burst so efficiently loosing color.