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Some information about MacroVision ... Video equipment, suitable for playback of rental video's, most of the time are equiped with something nasty called "MacroVision". On this page I'll try to give you information so you get the general idea behind MacroVision.

What is Macrovision?

MacroVision is a video copy protection method for video playback equipment. First used on VHS tapes, later adapted for DVD's, VCD's and SVCD's. It is used for pre-recorded videomedia.

You can detect MacroVision, by simply trying to dubb a protected tape, the video that goes through the recording VCR will get dark and then normal again periodically. The picture may also become unstable.

Sometimes Macrovision signals resemble false synchronization, and some TV-sets mistake them for the real synchronization failures. Also colors may vanish from the top of the picture. It resembles very much a mistracked video-tape.

Some TV-sets do not like Macrovision; the top of the picture might be unstable all the time and the colors may flicker. Specially projectors and large screen TV-sets show this effect.

If you have a TV that has an adjustement for picture height or vertical hold, you can fiddle around with those. Macrovision signals can be seen as very bright and very dark regions (vertical bars) near the top of the picture.

Most modern DVD and VCR's have MacroVision.

How it works

Here is a simple explanation of how the method works.

MacroVision abuses the Auto Gain Control (AGC) features of a video-recorder.

Normally the AGC is supposed to amplify weak signals and dimm the too strong signals.

MacroVision now inserts some non-standard signals in the non-visable area of the TV-picture.

The additional video information may make the AGC think that a sound picture is way to bright or way to dark.

The AGC kicks in and adjusts the video output to what it thinks should be. For example the picture get's to dark or to bright.

This tricks is repeated over and over again in a random order. The AGC therefor generates a too dark, then again a too bright, etc picture. Pretty annoying if you have to watch a movie that manifests this effect.

Note that the this effect only appears when the signal is redirecty by the VCR ...

So why isn't this happening when I hookup the playback device directly to my TV-set?

That's easy: most TV-sets do not have a AGC ! Those that have an AGC, behave differently than the one in your VCR.

Some VCR's, like Sony 8mm video, are not affected by MacroVision since the AGC is not similar to the ones required for MacroVision to work. Older VCR's (much older!) are not affected either since they do not always 100% match the specifications required for MacroVision.

Can I disable MacroVision?

Before we can give an answer to that question, you should know that modern video equipment like DVD-players can be "patched" to disable MacroVision. For example theYamakawa DVD player has a "secret" remote control code to disable MacroVision. Other players either have a similar code too, or there are hardware patches out there that do so. An example is theMacro-Vision remover by Nezzle which you can build yourself.

Simply rerouting video signal from TV to VCR or using aerial input/output does not do the trick, MacroVision is to well integrated in the video-signal.

Basically there is no quick and dirty trick to disable MacroVision, however there a boxes available that filter the video signal so MacroVision will not work anymore. These boxes can be bought on the Internet or at most electronics stores. Schematics to build such a box can be found in a lot of electronic magazines (for exampleElektor) as well.

Note: the MacroVision disablers or stabalizers for the US market (NTSC) are not suitable for the European market (PAL) and vice versa!

模擬CPS (Macrovision)

　　模擬CPS (Macrovision) 每個播放機中的Macrovision7.0電路能防止錄像帶（模擬的）的拷貝。通常稱爲APS (模擬保護系統). 帶composite 或s-video(Y/C)輸出端子的計算機視頻卡必須使用APS. Macrovision將快速調製的色突發信號("彩條")和垂直消隱信號("AGC")送到composite和s-video輸出端。　　因此，在95%的錄像機裏，會干擾電路同步和自動錄寫級別干擾。很不幸，這降低了圖片的質量， 特別是如果設備陳舊或是非標準。 Macrovision會引起彩條，變形，搖擺，黑白圖象，明暗交替。早期生產的播放機的模擬component　　視頻輸出端並沒有Macrovision，但在較新的播放機裏是必須的(指AGC,因爲component中沒有突發信號)。 盤片上的 "觸發比特"會提示播放機是否使用Macrovision AGC, 可以選擇2線或4線綵帶。每秒發生一次觸發，可以很好地控制視頻節目的哪一部分要得到保護。 盤片製作商會考慮拷貝保護的數量，然後付給Macrovision相應的版稅（每張盤幾分錢）。 　　和錄像機一樣，有些DVD是受Macrovision保護的，有些則不是。(要了解關於Macrovision細節，　　參閱STMicroelectronics' NTSC/PAL video encoder　　datasheets，在<www.st.com/stonline/books/>.)　　以上是DVD FAQ中的解釋。

編輯本段Macrovision 公司

　　Macrovision 公司(納斯達克上市公司)是電子許可、複製保護和數字權限管理技術的市場領先者。Macrovision的FLEXNet平臺是全球唯一一個通用的許可平臺，支持用戶方便地對他們的軟件進行定價、包裝和保護。有超過3000個軟件發行商發佈了FLEXenabled(TM)軟件，財富雜誌1000強企業中有幾百家企業爲更好管理他們的軟件許可使用了Macrovision公司的技術。公司在全球擁有700多個軟件許可、數字權限管理和內容保護專利。