Macrovision

Macrovision is a vicious method of completely screwing up the picture of a video stream - whenever the video has been copied.  It is a copy-protection scheme, hated by all. It is on both VHS tapes and DVD's.

A VHS videotape or DVD (no laserdisc or video CD players implement it) or digital cable/satellite boxes receiving a data stream encoded with Macrovision will cause a VCR set to record it to fail (excluding very old models, modified VCRs, or those approved for "professional usage"). This is usually visible as a scrambled picture as if the tracking were incorrect, or the picture will fade between overly light and dark. A 6-head or 8-head VCR (most are 4-head) can minimize this fluctuation, so it is not as noticeable.

This is achieved through a signal implanted within the offscreen range (vertical blanking interval) of the video signal—either physically recorded directly on the tape (as with VHS) or created on playback by a chip in the player (as with DVDs) or the digital cable/satellite box (as with all HDTV programs being down-converted to standard definition).

NTSC and other video formats store the video signal as “lines.” A portion of these lines are used for constructing the visible image by transposing them on the screen, but there are approximately 20 to 40 lines outside the visible range that are used for different things in different countries, like closed captioning.

Macrovision inserts pulses into this non-displayed area. These signals cause the automatic gain control on the recording VCR to compensate for the varying strength. This makes the recorded picture wildly change brightness, rendering it unwatchable. On most televisions, the viewer on the screen sees no effect in ordinary playback of the protected video because the signal is outside the visible area, but some TVs do not properly blank the vertical retrace and leave dotted white lines near the top of the picture. Some newer TVs also mistake the Macrovision pulses for synchronization pulses.

Another modification also used in Macrovision protection is the addition of colorstripes—rapidly modulated colorburst signals.

Macrovision Removal - there are many "underground" devices out there on the web for sale - that remove macrovision.  You simply feed the video signal into the box, and it outputs a clean signal with no macrovision.  Personally, I use the Canopus ADVC-100 which has a primary use of converting composite video to firewire so that I can capture analog video from my VCR into my computer via the DV capture card (I use a Canopus DV Raptor).  The ADVC-100 has an internal macrovision removal circuit.

Technical problems
Macrovision is considered a nuisance to specialist users because it may interfere with other electronic equipment. If one were to run their video signal through a VCR before the television, some VCRs will output a ruined signal regardless of whether it is recording. This also occurs in some TV-VCR combo sets.

The signal has also been known to confuse home theater line doublers (devices for improving the quality of video for large projection TVs) and some high-end television comb filters.

Legal issues
Some DVD players give the user the option of disabling the Macrovision technology. This is possible since the signal is not stored on the DVD itself; instead commercial DVDs contain an instruction to the player to create such a signal during playback. Some DVD players can be configured to ignore such instructions.

There are also devices called stabilizers, video stabilizers or enhancers available that filter out the Macrovision spikes and thereby defeat the system. The principle of their function lies in detecting the vertical synchronization signal, and forcing the lines occurring during the vertical blanking interval to black level, removing the AGC-confusing pulses. They can be easily built by hobbyists, as nothing more than a cheap microcontroller together with an analog multiplexer and a little other circuitry is needed. Individuals less experienced with such things can purchase video stabilizers off of the internet from companies such as Dimax in Israel. The best device for defeating Macrovision is a Time Base Corrector (TBC), although they are more expensive than the simpler video stabilizers.

The MPAA maintains it has every right to limit copying of movies, comparing DVDs to pay-per-view where the consumer is allowed to view the movie in question but nothing more. Many are concerned that the organization is attempting to quash fair use by disallowing consumers to make personal copies.

United States fair use law, as interpreted in the decision over Betamax (Sony Corp. v. Universal City Studios), dictates that consumers are fully within their legal rights to copy videos they own. However, the legality has changed somewhat with the controversial Digital Millennium Copyright Act. After April 26, 2002, no VCR may be manufactured or imported without Automatic Gain Control circuitry (which renders VCRs vulnerable to Macrovision). This is contained in title 17, section 1201(k) of the Digital Millennium Copyright Act. However, there are a number of mostly older VCR models on the market that are not affected by Macrovision.

On October 26, 2001, the sale, purchase, or manufacture of any device that has no commercial purpose other than disabling Macrovision copy prevention was made illegal under section 1201(a) of the same controversial act.

SafeCast

SafeCast is a type of software copy protection for legacy computer applications marketed by Macrovision. It is or has been used by such software packages as Intuit's TurboTax and many recent Adobe software products, and has occasionally been the source of controversy.

RipGuard

In February 2005, Macrovision introduced their new RipGuard technology. This is designed to prevent (or reduce) digital DVD copying by altering the format of the DVD content in such a way as to disrupt the ripping software. Macrovision claims that 97% of all current DVD rippers will not be able to copy a DVD protected by RipGuard technology, however, it can be bypassed with the use of AnyDVD, DVDFab Decrypter, RipIt4Me, or, on Mac OS X systems, MacTheRipper 3.

RipGuard also renders the formatted section of DVDs unwatchable on some players. The audio is intact, but the image appears scrambled. This has been confirmed with Toshiba DVD/TV combo model MD20FL1.

Cactus Data Shield

Cactus Data Shield (CDS) is a form of copy protection for audio compact discs developed by Midbar Tech, now owned by Macrovision. There are several types, commonly described as CDS100, CDS200 and CDS300. However, there are about seven subtly different versions of CDS200. CDS200 discs are usually labeled as 'copy controlled' (CCCD). (They are formally not CDs). CDS300 discs are labeled as 'content protected'. CDS300 discs cannot be ripped by iTunes in particular. However, they contain copies of the music in WMA format, which allow to be burned to cdr three times.

CDS300 was rebranded 'Totalplay' in 2005 and contained a Windows CD software driver that denied access to the audio portion of the music disc. Apple Computers were immune to CDS300 copy protection. However, it could still be ripped on the Windows platform by using the Musicmatch player. It exists today as an interesting legacy product that is incompatible with the legions of Itunes users and Ipod owners that are still increasing in number..

CDS100 is incompatible with many cd players, particularly car cd players, which caused negative press around 2002. The company claims this was fixed in (modern versions of) CDS200, despite many users reporting otherwise.

CSS decrypting software

CSS decrypting software (such as DVD Decrypter, AnyDVD and DVD Shrink) allows a region-specific DVD to be copied as an all-region DVD. It also removes Macrovision, Content Scrambling System (CSS), region codes, and disabled user operations (UOPs).

The Demise of "DVD Decrypter" - thanks to Macrovision

In June 2005, Macrovision sent a cease and desist letter to "Lightning UK!", the maker of the famous DVD Decrypter utility, a program that allows users to backup their DVDs by bypassing CSS and Macrovision protection, whose only real use is for piracy of DVD's. They later acquired the rights to this software and withdrew it from circulation on the internet.  But as soon as DVD Decrypter was gone, "Any DVD" came into the scene - which works much better because it is updated constantly, and removes macrovision and encryption "on the fly".

In June of 2005, Macrovision sued Sima Products under section 1201 of the DMCA, claiming that Sima's video processors provided a way to circumvent Macrovision's analog copy protection (ACP). As of June 2006, Macrovision received an injunction barring the sale of this device, while the court proceedings continue.