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  1. Member dellsam34's Avatar
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    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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  2. Member Cornucopia's Avatar
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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.

    Scott
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  3. Member dellsam34's Avatar
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    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.
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    What is the theory behind this tech? Why was PCM data encoded in a video stream?
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  5. Member dellsam34's Avatar
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    Originally Posted by davexnet View Post
    What is the theory behind this tech? Why was PCM data encoded in a video stream?
    Back in the day video tape was the only mean to store a tremendous amount of digital audio data, DAT and CD where not on the scene yet, Some artists have mastered their audio tracks on U-Matic and Betamax formats and some semi pro used VHS and Video8 formats coupled to or built in a VCR.
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  6. Member Cornucopia's Avatar
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    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.

    Scott
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  7. Member dellsam34's Avatar
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    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:
    https://github.com/ololoshka2871/pcm_coder/releases/tag/v0.8
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    Last edited by dellsam34; 13th Jul 2020 at 17:37. Reason: Updated the link
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  8. Member dellsam34's Avatar
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    Originally Posted by dellsam34 View Post
    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?

    The reveal !!!!
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  9. Member dellsam34's Avatar
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    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:

    Code:
    pcm_coder.exe --ntsc --16 "c:\FilePath\FileName.wav" "c:\FilePath\FileName.avi"
    Replace ntsc with pal for PAL and 16 by 14 for 14bit encoding.

    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.
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  10. This is great! I love saving audio/video/data in weird, strange ways.

    I wonder if it is possible to save a digital video stream like this...

    Or convert video to audio (There are several funky programs for this, small-band/slow-scan television.) and save it as PCM...

    In the 90's there was a program and card that allowed you to save data backups with DOS/WIN 3.11/95 on VHS tapes. It used an ISA card in your PC to convert data to composite that you could then record on a VHS tape. And play back, of course.

    (I suppose you can use any video capture tape/device as long as it has sufficient resolution and stability.)

    16mm film hmmm....
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  11. Member dellsam34's Avatar
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    Yah, I know what you are talking about:

    https://youtu.be/TUS0Zv2APjU
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  12. Member dellsam34's Avatar
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    This is the first time I've seen digital PCM stored on 1" type C reel to reel video tape, Enjoy the song:
    https://youtu.be/jlt0m0vSEwc?t=1682
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  13. Originally Posted by dellsam34 View Post
    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:
    https://github.com/ololoshka2871/pcm_coder/releases/tag/v0.8
    What the big F is Ich Troje doing on the tape? Surprised anybody knows this band? They are from my country, pretty legnedary in some circles.
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  14. I have done the reverse, storing video in the audio channel of cassette and reel to reel.

    Sure, it was only a few frames per second, and something like 120 or even 60 lines. But it was fun...

    I forgot what I stored. If I find the required programs I can make a short video of the recording.
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  15. I successfully decoded the sample provided using this software on Win7 x64 over VirtualBox with a Linux host

    PCM Data 16 _ 44056 .flac

    Here is my full post:
    https://www.tapeheads.net/showthread.php?t=82905

    Reply #17

    I'm also on this thread:
    https://forum.videohelp.com/threads/394168-Current-status-of-ld-decode-vhs-decode-%28t...nals%29/page10

    Good quality content!
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