How can I recover digital audio that was encoded on VHS cassettes around 1987?

I have some live music recorded in 1971 on reel-to-reel tapes that I transferred to a digital format around 1987. I no longer have access to the reel-to-reel tapes. At the time, there was no direct PCM recording option on VHS machines (it came out soon thereafter). The recording studio had a large box that took analog input and converted it to digital and stored the digital signal on the video section of VHS cassettes as a video signal that encoded the audio.

I do not recall the encoder but I have the VHS tapes and would like to recover the audio.

How could I go about recovering the audio that is encoded on these VHS tapes? What might have been the machine encoding scheme used and if identified, how could this be decoded today?

WilliamKF

out-of-date-format
data-recovery
vhs
pcm
audio

Comments

Ben Fino-Radin: I've never encountered the format in the wild and as such won't hazard on answer, but it seems likely that they are D-VHS tapes: http://en.wikipedia.org/wiki/D-VHS
WilliamKF: @Ben Fino-Radin Looking at the article you point to I see it states "The format was introduced in 1998." so that cannot be the case since the tapes were made around 1987. I believe the machine was a regular VHS machine it was just recording video that encoded the audio from a separate encoder device.
Ben Fino-Radin: Right you are – sorry, only gave it a cursory glance.
Donald.McLean: Is this what you're talking about? http://en.wikipedia.org/wiki/PCM_adaptor
WilliamKF: @Donald.McLean Going from memory, I think that would be the one! Now how do we decode it today?
Andy Jackson: This hobbyist site has nice shots of the video and even, it seems, a hardware DIY option. Alternatively, you could get the video off the cassettes as MPEG or similar and then investigate options to decode the signal in software.

Answer by Donald.McLean

I think that your best bet is to do a web search for an independent audio consultant. It would have to be someone who has been in business since 1987 and has worked with that technology. Such a person would either still have the appropriate equipment or would know where to get it.