Press & Media - oyvindln/vhs-decode GitHub Wiki


Hello, my name is Harry Munday, I'm the documentation writer & hardware tester for the verious segments of the projects.

Software: VHS-Decode, CVBS-Decode, HiFi-Decode, TBC-FL2K-Player, CXADC Driver, RTL-SDR HiFi-Decode

Hardware: CX-Cards (& CXADC Driver), DomesDayDuplicator, RTL-SDR

To a limited extent ld-decode as well due to directly shared tools and development.

For questions, live demonstrations or just general support regarding the project email [email protected] or reach out to TheRealHarrypm#1667 on Discord, I am UK based but not always on GMT standard time.

For quick keyword lookup and historical development references and links please see my old (semi-depricated) Google Doc.

Who is this document for and why?

This document is being made after a certain poorly written hack a day article, we love media coverage but hate when it promotes out of date information and lacks breaking down the most important aspect, that the initial FM RF capture is the preservation method but is very much so agnostic or universal on pratically all analouge tape formats.

We can safely say that analogue capture has hit its end in terms of tehcnological aqusition, and archival, now processing it into images, sound and digital data is what vhs-decode/hifi-decode/cvbs-decode/ld-decode provides for those archival captures today and in the far future.

It should be clearly stated that this is not just a single project, in fact it's a highly accessible media-preserving toolset with a family of projects and developers and tinkers working together to improve on digital archival and preservation of analogue media, entirely replacing ineffective old and cost inflated methods, allowing anyone with standard computing hardware to get better then restoration house results at home.

The RF Capture projects & hardware in order of development is CXADC (Driver for PCI/PCIe 1x CX Cards) & DomesDayDuplicator (USB 3.0 based solution)

The Decoding projects are in order of development LD-Decode, VHS-Decode, CVBS-Decode, HiFi-Decode & TBC-To-Analogue-FL2K.

The projects are all under the DomesDay86 community umbrella with members sharing code, sample data and generally assisting and advancing each others work, with core members and developers in the United Kingdom, United States, Scandinavia & Mainland Europe.

Short Summary

Analogue video and HiFi audio is stored as frequency modulated (FM) signals on magnetic tape, via RF capture with an ADC off pre-amplified signal points (test points normally) directly before or on processing boards inside a VCR the signals be captured in its most direct state, this is before any hardware processing past tracking and basic amplfication after the heads read the signal off the tape, allowing us digitally capture and preserve that unprocessed RF FM data on 25-100GB M-Disks, Sony Optical Archive or even Cloud providers for example, complete long-term universal preservation of original source signal, this RF signal or waveform can then be losslessly compressed down with FLAC or re-sampled without any effect on video quality simmler to raw digital video.

Today we can process these captured signal with software de-modulation and time base correction, this detaches the analogue media preservation and inital capture from the limits of hardware processing inside a VCR and ageing correction hardware such as time base correctors of witch are scalped to death, or limited FPGA based real-time systems already on the market for commercial use.

What was impossible with dedicated hardware solutions witch provided an limited backed-in results has been removed from the equation entirely if you don't like the initial results just adjust the commands and decode it again.

The VHS-Decode & HiFi Decode

Diagrams Page here

The workflow is not a magical black box its as simple as the following:

FM RF Preservation

RF Data after capture or even during capture in some cases can then be FLAC compressed and even down-sampled allowing for less costly long term storage of source material signals.

The Main Benefits

  • Source Signal Archival (Tape FM information is preserved)

  • Smaller Archives Compared to lossless V210 & JPEG2000

  • Full-Frame (4fsc) Signal Processing (full signal area preservation)

  • Software Time Base Correction

Software extraction of Vertical Blanking Interval (VBI) data such as:

  • Closed Captions (CC) Subtitling found on broadcast airings and NTSC/PAL home TV/Movie releases.

  • Teletext - UK/European Subtitles & Information Boards

  • VITC - Vertical Interval TimeCode, widely found in broadcast and SVHS tapes.

  • VITS - Vertical Interval Test Signals, widely found in broadcast.

Is this new technology?

Nope, the ADC in the DomesDayDuplicator and the CX Cards are both using ADC hardware from 2000~2002 era for example, but this is the first fully open-source workflow that has a built up a hardware and software tool suite anyone can deploy and that is truly future proofed due to being entirely open-sorced.

Now anyone who is well informed will know Cube-Tec have there own version of direct RF signal processing but its a "black-box" solution using an FPGA based system, aimed primary at broadcast stable formats like BetaCam/BetaCam SP, (witch vhs-decode has the ability to support) however what there solution fails to offer is the original digitised FM RF signal of the actual tape source so its still hard limited to real-time processing using whatever code is on the FFPGAs.

The RF Capture Hardware

We have two standardised methods.

CX Card & DdD

DomesDayDuplicator - Left which is a plug and play USB 3.0 capture device that works on Windows/Linux/MacOS, with original fabrication & flashing docs having been re-made so that anyone can order and build at home without any reading past 1 page.

CX Card - Right a PCIe 1x computer add-in card, PCIe version was standardised due to noise performance and ease of modification.

Analogue Devices AD8367 a basic RMS amplifier that allows you to replace the on-board gain stage of the CX Card or extend cabling.

(CX Card is propped up on a M.2 to PCIe 8x riser, this does not have any significance)

Media Examples

RAW & Processed data can be directly obtained for viewing here on the Public Shared Drive.

Note while this media is publicly available, we respectfully ask for it to be correctly attributed to the contributors of the community as this segment of the project is 100% community driven.

There are a few people who have published their media online and their channels are listed below the reason why Odyssey is liked is due to zero processing or transcoding of media files witch makes it ideal compared to YouTube witch requires heavy upscaling or black image data will be utterly crushed by compression artefacts and SD video is quite unusable.

Odysee VHS-Decode - TheRealHarrypm#1667

Odysee The Rewinding - MrCarter#8417

Odysee Zcooger - Zcooger#3991

Zcooger's older Tests:

DMR-ES15 / VHS-Decode 2021

Software Dropout Compensation 2020

Further Reading

Order of Documentation