How does a DVD recorder detect DRM on an Analog video signal?

[Hail_Ants]

I finally started using a DVD component unit (usually I do all my recording via PC) and was very surprised when I played an Amazon download and hit record on the recorder and it stopped and displayed “COPYRIGHTED CONTENT - CANNOT RECORD” or words to that effect.

I’m using the S-video input which is analog (only digital video-in would be HDMI, right?) so how does the device detect copy protection? I’m not asking for instructions on how to defeat it, I just don’t understand how they’ve plugged the ‘analog hole’ for video.

[jz78817]

Analog Copy Protection. Colloquially known as “Macrovision Protection.”

[Digital_Stimulus]

@jz78817

Analog Copy Protection. Colloquially known as “Macrovision Protection.”

Quoting from that link:

Macrovision’s legacy analog copy protection (ACP) works by implanting a series of excessive voltage pulses within the offscreen VBI lines of video. These pulses are included physically within pre-existing recordings on VHS, and generated upon playback by a chip in DVD players and digital cable/satellite boxes. A DVD recorder receiving an analog signal featuring these pulses will detect them and display a message saying that the source is “copy-protected”, followed by aborting the recording.

ETA: there may be further methods; ACP is the first mentioned…