This is the VHS-Decode Wiki written and maintained by Harry Munday (harry@opcomedia.com) Inside this wiki and its pages, you will find everything! From easy-to-understand technical guidance and notations for getting a signal out of VCRs, capturing original FM RF signals off of tapes, storing them and finally processing them into lossless digital media archives.
VHS-Decode is part of a family of software sharing the same tools & developers!
CVBS (Composite) Decode / HiFi Decode / RTLSDR HiFi Decode / LaserDisc Decode / MUSE-Decode / CD-Decode / FL2K TBC Player
Visit Donations if you want to support the work!
We have an introduction YouTube / Odyesee video!
And more content:
Odysee Official VHS-Decode - therealharrypm
Odysee The Rewinding - MrCarter
YouTube The Video Dump Channel - Jitterbug
Thanks to a flexible range of low-cost analogue to digital converter options direct digitisation and archival of many magnetic analogue media formats can be done not only properly, but affordably with original FM RF (Frequency Modulated Radio Frequency) signals being captured and preserved in the digital file realm in generic PCM samples.
This is dubbed as the "FM RF Archival" method.
Unlike limited baked-in standard S-Video/Composite, or "baseband" video & audio capture, FM RF capture allows the original tape signals to be stored making a true digital master copy of your analogue media, thus removing the need for expensive time base corrector or even working physical players in the future.
The decode family of tools brings you a state of the art archival toolchain to make use of these FM RF archives today!
Rather than a wide range of different video capture equipment with highly variable quality factors (visual results) the hardware for the actual "capture" side of things is much more generic in complexity being direct ADC capture, and generic PCM sample data, with most setups now capturing directly to lossless compressed FLAC.
With the conversion from raw data to baseband, then to digital video being a fluid copy-paste drag 'n drop experience in the software domain for many tape formats not limited to just VHS or SVHS, the burden of effort for professional archives is no longer tied to high cost real-time equipment, just working well enough machines that can read the FM off tapes.
You are only limited to the potential of the media format instead of just some capture card or codec used to transfer it!
Anyone with a standard desktop or laptop from the last 15 years can use the decode suite, it's cross-platform and entirely open-source, freely providing a full suite of "after the fact" broadcast level processing & manipulation tools with a full-frame software-based time base corrector, drop out detection & compensation, anyone can expand the features or port it to new platforms.
Breakdown of FM RF ArchivalBypass all non-essential hardware, and process it all in software directly.
Capture today, decode tomorrow!
To see more expanded examples, see The Visual Diagrams Page.
Note
Sony's 8mm formats Video8 & Hi8 is only 1 RF signal point that contains Video/HiFI FM/RCTC-Timecode, but VHS & Betamax are two separate FM RF test points.
Capture & Decode WorkflowFor various tape media formats we create what we call an "RF Tap" and it's as simple as the following: (2020-2022 workflow)
The more optimised workflow employs a high impedance amplifier between the Video/HiFi tap and your capture devices: (2023-Current)
RF Capture Hardware (CX Card, CX Cards Clockgen Mod, DdD, MIRSC, or any ADC platforms that can provide PCM sampling will work)
Practically Any VCR/VTR/Camcorder --> Analog to Digital Converter "ADC" 28-40msps --> Generic RF File of Video/HiFi Signals.
FLAC Compressed RF Capture --> Optical Archive or LTO Tape Archive.
HiFi FM File (RAW or FLAC) --> HiFi Decode --> Demodulation & Noise Reduction --> FLAC 48kHz 24-bit audio file.
Video FM File (RAW or FLAC) --> VHS-Decode --> Demodulation & Time Base Correction --> Composite or S-Video .TBC Files video.tbc & video_chroma.tbc --> VBI Data Extraction via ld-process-vbi (Closed Captions / VITC etc) --> Updated JSON file.
ld-analyse Framing/Levels adjustment & inspection --> TBC Video Export (FFmpeg & Chroma-Decoder) --> Comb Filtering & YUV Encoding --> Final Interlaced FFV1 10-bit 4:2:2 Video File.
Interlaced Video Files --> Deinterlacing --> Use on modern devices.
Unlike conventional methods, software decoding provides 4fsc sampling in non-square pixels so not only the visual picture area but the entire signal frame including the vertical blanking area (VBI) so information such as Closed Captions, VITC Timecode and Teletext can be visually inspected and some can be digitally decoded automatically via ld-process-vbi to a standard .JSON metadata file or via 3rd party tools like VHS-Teletext.
Thanks to the Time Base Corrected Format:
TV System Full-Frame 4fsc Frequency Frame Rate Field Rate Data Rate CVBS Data Rate Y+C PAL 1135x624 17727262 Hz 25i 50i 280mbps 2.1GB/min 560mbps 4.2GB/min NTSC 910x524 14318181 Hz 29.97i 59.94i 226.5mbps 1.7GB/min 453mbps 3.4GB/minThe .tbc format is a fully open standard method of containing the full 4fsc sampled contents of a composite or Y/C separated video signal, this is similar to the 4fsc D2/D3 lossless SD broadcast tape formats but in a binary digital file format ready for software chroma decoding or playback back to analogue systems via DACs.
The data is stored in the 16-bit GREY16 format and Luminance (Y) files can be used with FFmpeg directly to render a greyscale full frame "open-matte" video, however the Chrominance (C) is QAM modulated hence "Digital S-Video" being a apt term.
This baseband signal file or file set can also be opened in GNUradio it also allows backwards support for playback to analogue systems as media see Analogue Playback for more information.
Post Inspection & Levels AdjustmentThanks to the ld-tools suite but critically ld-analyse (TBC Inspection Tool), complete software control & adjustment over decoded 4fsc Composite/S-Video is visually possible in the baseband signal domain, before final YUV conversion replacing legacy scopes and hardware chroma decoding.
After decoding and inspection/adjustment, the .tbc files can then run through the chroma-decoder (comb-filter in NTSC speak) which recovers the original colour and can output it as a RGB or YUV stream merged with the Luma B/W information, however this task today is virtually hands-off with tbc-video-export.
For viewing media we recommend players such as Media Player Classic or VLC.
The default output is lossless compressed archival standard interlaced 10-bit 4:2:2 FFV1 video & FLAC audio in the reliable .mkv (Matroska) container, but many FFmpeg Profiles are available for legacy compatibility including V210, IMX50 & ProRes HQ.
Lossless Cut & DaVinci Resolve are recommended for editing.
After initial interlaced video files are created, it can then be be de-interlaced quickly with bwdif. However, today more powerful deinterlacers like QTGMC can be easily used inside of StaxRip or Hybrid with a few clicks, providing a very high-quality motion accurate progressive video files, ready for modern progressive system only use.
Current State & Development NotesReal-time FLAC compressed FM RF Archival on most hardware due to FLAC v1.5.0 - Feb 2025
Decode now supports 2" Quaduplex 819-line and 405-line, and SECAM colour decoding is established - 2025
HiFi-Decode now is equal if not greater than last generation decks for HiFi FM decoding - 2025
Decode has self-contained cross-platform support, and has standardised multichannel RF capture workflows - 2023
Decode supports decoding both stable and especially unstable media incredibly well with added support for SMPTE-C/Umatic SP/EIAJ/Philips VCR - 2023
Decode has support added for Video8, Hi8 - 2022
Decode surpasses in-deck time base corrector hardware & rivals dedicated commercial units - 2021
FM RF capture and post software decoding just cuts out the signal handling, not the physical handling.
Your VCR needs to be mechanically stable and able to track the tape. This means decks that are dramatically out of spec will have to be serviced/adjusted.
Standard capture rules of thumb such as tracking adjustment per tape/segment with channel up/down buttons/sliders or knobs on pro decks and keeping the heads/guides clean still applies, as with any tape media playback as long as the heads read the signal RF capture will work on it.
In the future, It would be ideal to capture all head drum signals with a custom amp/capture board and then do tracking in software, but for now, refining an already tried and working test point path based capture and increasing format support is the clear priority alongside increasing the processing speed, and building on standardised workflows.
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