Processing Recommendations?

The EBU R128 Standard or -11 LUFS normalisation is recommended as its widely used in broadcast/online production this can be done with StaxRip or with FFMPEG

Types of Audio on VHS

FM HIFI Stereo (1 Signal)

Linear Stereo/Mono (CH1) (1 Signal)

Linear Time Code (CH2) (1 Signal) (Broadcast Decks) (SMPTE 12M LTC)

Dolby Stereo (2 Signals) (1980's Prosumer & Broadcast Decks)

Types of Audio on S-VHS

All of the above but mostly HIFI Stereo.

How to capture & process VHS audio

Capture as you would for video however 10 MSPS is more than enough compared to 17.9-20msps recommended for video.

Sadly VHS Decode does not have integrated audio decoding/conversion integrated but there are solutions:

1. VideoMem's Superheterodyne Decoding Tools GNU Radio script-based HIFI decoding tool.

2. Using decent low self-noise 24/32bit 48-192khz audio interface/recorders on the demodulated baseband output on the back of the VCR.

Mixed Signal Capture?

As this idea has been tried sadly to no avail causing issues so the only option with currently available hardware is septate capture.

ADAT Audio Tapes?

Currently, there is no R&D in this segment players are still around at 100-300USD on the market on eBay etc in 2022 as this is more a niche segment but a valuable one no less, this is written here as a reminder to anyone feel free to expand on this.