I've seen projects for capturing VHS video tapes (VHS decode) and Teletext from Video tapes into PC using some sort of TBC software but I've never heard of a project for PC software that can recover PCM data from video frames, The only way of doing it is using the ancient Sony PCM-601ESD PCM adapter or the hardware attempt of someone from south Africa who has been working on this project for over a decade, this is his third gen design, the Corona virus lock down helped him focus more on this project.
Since the video frames are just 0's and 1's represented by black and white blocks I'm thinking it is possible to make a computer software that can recover those bits into a usable PCM stream as digital wav audio.
I'm sitting on a bunch of VHS PCM tapes and while I have the Sony PCM adapter to recover the audio from them I just though maybe someone with coding skills could start such a project for the sake of experimenting.
Here is a sample from one of the tapes:
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I would suggest that, since you have the adapter, you provide an "encoded" AND a "decoded" copy of the same segment, for reference verification purposes.
Also note: there were other, similar processors - PCM-F1 was what I used back in the day (hooked up to a Umatic deck most of the time), and I think there were the 601/701 series as well. Those could assist in comparison.
Also, part of the issue that dude is having is because he is assuming 44100 Hz sampling. It wasn't. It was 44056. And many of the processors were 14bit, only a few were 16bit.
I would like to keep it a mystery unless someone has a PCM adapter to take a challenge and let us know what that 30 sec audio is. Fun! Isn't it?
Anyway, No his problem has nothing to do with 44056 Hz because he is using an actual CD player to generate the signal and encode into video, Besides 44056 Hz recording didn't last long, It was replaced pretty quickly by 44.1 KHz which led to the birth of the DAT format and the additional 48 KHz. Sony PCM-601ESD being the only one with SPDIF IN/OUT and 16Bit capabilities.
What is the theory behind this tech? Why was PCM data encoded in a video stream?
Not the ONLY means (DASH, SoundStream, DigiStudio, etc), but this certainly put the means to record audio digitally into the hands of many, in a straightforward way, using existing storage formats that intrinsically had enough bandwidth.
I'm back to this thread with some new information, On YouTube comments someone sent me a link to download a Windows GUI app for a PCM Decoder, Basically you load a captured PCM video or hookup live to a capture card from a VCR playing back a PCM encoded tape and it will decode the video and save as WAV audio file in 16/44.1.
The attached package includes ni-labview-2019-runtime-engine to be installed first, then DSEG7Classic-BoldItalic second and then run the PCM Encoder by clicking pcm application.
If you are interested in PCM Encoder and you like script $hit (I don't) here is the encoder page:
Last edited by dellsam34; 13th Jul 2020 at 16:37. Reason: Updated the link
The latest Techmoan video about PCM recording motivated me to give the PCM encoder a try, It's a script based app but pretty straight forward, First I installed the package from github, Then extracted the folder and right clicked on it while holding shift key and chose commend line here, then in the DOS looking window I typed in the following commend, You can copy/paste it from here:
pcm_coder.exe --ntsc --16 "c:\FilePath\FileName.wav" "c:\FilePath\FileName.avi"
The video generated is AVI 720x525 for NTSC, it needs to be cropped to 720x480 with vdub (losslessly and quickly). After that you can play the file on a media player that has composite output and record to a VCR, Your music will be stored into VHS. Voila!
Note: I imported the generated video file into the PCM Decoder app in post #7 and it played it without cropping, in setting you have to reverse the field order.
Credit goes to Zcooger for his assistance.