Colour Under Tape Signal Chain

How a VCR works

Magical Magnetic Tape, Little magnets flying around on a drum.

Recorded on Media

TV Station --> Composite signal 525/625 line signal --> Communications System --> FM Modulation --> Broadcast via Antenna or Ground Coax --> Received by VCR --> De-Modulated Composite/NICAM HiFi --> Amplification & Processing boards --> Modulated for Tape Format --> Signal Sent to Video/HiFi Heads --> Magnetised in strips on magnetic tape.

Composite signal (525/625 line) from device or camera --> Amplification & Processing boards --> FM Modulated for Tape Format --> Signal Sent to Video/HiFi Heads --> Magnetised in strips on magnetic tape.

Recorded to Media

Video Tube or CCD Image Sensor / Analogue Microphone --> Analogue/Digital Processing ICs --> Modulated Amplified Signal --> FM Modulated for Tape Format --> Signal Sent to Video/HiFi Heads --> Magnetised in strips on magnetic tape.

Baseband Composite/S-Video signals are also output live from the video IC.

Playback From a VCR

Tape moving over heads --> Heads reading signal --> Amplified & Tracked by ICs --> Demodulation & Filtering --> Time Base Correction --> Composite/S-Video Output

Time Base Correction is done directly after demodulation inside VCRS with a TBC but is done after full processing with external TBC's.

Capture

CVBS - Composite & S-Video

Takes the processed signal from a VCR out of the baseband Composite or CVBS output, S-Video is Y/C separated and can yield cleaner results.

FM RF

Takes the unprocessed signal from a VCR before the filtering & demodulation stage, this is right after the pre-amplifiers or amplification stage.

Tape Inside VCR --> Tape Heads --> Signal Amplification & Tracking --> FM RF Signal Test Points --> Demodulation and filtering boards --> CVBS Baseband Signal

Baseband Hardware

So anyone who is 1-2 days into this rabbit hole will have found Blackmagic Analogue to SDI / AJA Analogue to SDI / Magewell AIO etc etc there are desktop and usb versions of these capture devices, but while yes they all use the analogue devices ADV8472 chips while they pretty much the end of the analogue all-in-one processing IC's if you give it enough ram for its TBC/Frame Store its very good but its still a baseband capture granted an over 8 times oversampled one but its still limited to the initial processing made by the VCRs filtering and demodulation boards.