Draft:.TBC Time Base Corrected Format

The .TBC format created by Chad Page, is a free to use and open source developed video signal file formatting standard for uncompressed decoded analouge video signals after software time base correction.

This format was orignally developed and used for the Domesday86 LaserDisc Recovery Project preserving the 1986 BBC LaserDiscs orignal modulated video/audio/data signals directly off the laser reading the pits of the disc.

Related is the open source hardware DomesDayDuplicator (DdD) a USB 3.0 40msps RF capture device, standerdised by the projects for capturing orignal modulated RF signals off laser-discs but is compatable with analouge tape formats, but not composite video directly.

Software Time Base Corrected File
The format is a lossless and headerless, 4fsc sampled digital file format not dissembler to D-2 & D-3 video tape, storing time base corrected composite/s-video (combined or luminance/chrominance separated) analogue video signals in 16-bit unsigned grey scale "GREY16" values allowing signals to be stored and processed on affordable mass storage HDD/SSD drives or archived to optical discs such as M-Disc or Sony ODA and standard LTO data tapes.

These can be inspected inside the open source tool ld-analyse for frame by frame signal analysis on Windows, Linux & MacOS then files can easily be encoded to a video file via FFmpeg typically to a lossless interlaced FFV1 10-bit 4:2:2 file using the .mkv container then de-interlaced via W3FDIF or more modern de-intelracers like Avisynths QTGMC and IVTC for 24p or film content.

Media sources like LaserDisc and Composite (CVBS) are stored in one single TBC file and colour-under tape formats such as (S)VHS, BetaMax, Umatic, Umatic-SP, Video8, High8, Video2000, Philips VCR, Philips N1500, Philips N1700 have luminance/chrominance separated into two TBC files allowing for cleaner direct image processing for black and white but especially colour images, notablaly the chroma is QAM modulated as such this is playback compatiable with standard S-Video output.

Formats like Betacam & Betacam SP, are still in developmnet stage (FM Demodulation filters) but will be later supported by the system like the EIJ-1, EIJ-2, 1" Type-C formats..

History & Current Day Usage
While originally developed for LD-Decode due to being opensorce it has subsquently gained wide usage and development expansion by the VHS-Decode (FM Modulated tape decoding, not limited to just VHS) & CVBS-Decode (composite video decoding) projects, under the domesday86 community creating a modern archival ecosystem, consisting of directly digitizing the original modulated or even baseband composite signals off analogue mediums to be preserved and de-modulated later, skipping the immediate and optional processing of dedicated internal and or external hardware entirely removing the need for physical time base correctors commonaly required for reliable standard capture.

Use In Lossless Analogue Playback
As the format allows for composite/s-video streams to be stored with sync signals (sub-carrer locked or line-locked), the files contents be streamed directly to an Digital to Analogue Converter (DAC) for live real time playback to an CRT or equipment with analouge inputs currently this is achieved with low cost USB 2.0/3.0 VGA adaptors that use the Frisco Logic 2000 (FL2K) chipset and a modified driver for Windows & Linux publically available on GitHub. DdD-SMPTE-Colour-Bar-PAL-VHS-SP - 2021.png Decoded in 2021 - VHS-Decode

Note: Image brightness levels may not be displayed correctly on your computer display.]]

General Information

 * Format Name:  TBC  Time Base Corrected


 * Year introduced: 2018
 * Developer: Chad Page (Primary Developer)
 * Format Type: 4fsc Composite or Y/C

Primary Data

 * TV System: PAL/PAL-M/NTSC/NTSC-J/SECAM/MESECAM
 * Data Format: 16-bit unsigned grey scale
 * Image Area: Full VBI/Active/Sync
 * Format type: digital composite & digital s-video
 * Resolution PAL: 1135x625
 * Resolution NTSC: 910x525
 * Sampling Rate: 4fsc PAL (17727262 Hz)
 * Sampling NTSC: 4fsc NTSC (14118181 Hz)
 * Data Rate PAL:
 * CVBS  2.1GB/min 35MB/s (280mbps)
 * Y+C    4.2GB/min 70MB/s (560mbps)
 * Data Rate NTSC:
 * CVBS 3.4GB/min 56.66MB/s (453mbps)
 * Y+C   1.7GB/min 28.33MB/s (226.5mbps)

Metadata

 * Format: .JSON (file is metadata for the single or pair of TBC files)
 * Information Type: Frame Descriptor Table
 * Information Content: System NTSC/PAL, Frame Count, Signal Dropouts, Black Signal To Noise Ratio, White Signal To Noise Ratio, Closed Captioning, VITS Signals, VITC Timecode.

Audio

 * Codec: PCM Uncompressed & FLAC Lossless Compressed
 * File Extension: .WAV or .FLAC
 * Bit depth: 24-bit Integer or 32-bit Float
 * Sample Rate: 48khz ~ 192khz

Direct CVBS

 * filename.tbc - CVBS Image Data
 * filename.tbc.json - Frame Descriptor Table
 * filename.wav - External Audio

LaserDisk

 * filename.tbc - CVBS Image Data
 * filename.efm - Digital audio/data track
 * filename.pcm - Uncompressed 44.1Khz 16-bit stereo analogue sound track
 * filename.log - Date Indexed Action & Decoding Output Log

Tape Media

 * filename.tbc - Luminance (CVBS) Image Data
 * filename_chroma.tbc - Chrominance Image Data
 * filename.tbc.json - Frame Descriptor Table
 * filename.log - Date Indexed Action & Decoding Output Log
 * filename.wav - Linear Audio (Mono/Stereo or LTC timecode)
 * filename.flac - HiFi Decoded Stereo

TBC File Processing Suite
Linux & Windows supported, ld-tools is a set of tools to handle and process TBC files.

Tools Exclusive to use with the DomesDayDuplicator:
 * ld-process-vbi - Reads VBI Data such as time codes, closed captioning, CGMS-A saving its traslated value into the .JSON metadata file.
 * ld-process-vits - Reads VITC test signals and saves updated Black & White SNR values into the .JSON metadata file.
 * ld-process-efm - LaserDisc Only, processes digital audio data.
 * ld-export-metadata - Exports .JSON metadata to stardard formats for external use.
 * ld-chroma-decoder - Decodes the QAM modualted chroma signal for muxing to normal colour video.
 * ld-chroma-encoder - Encoder that takes raw video and encodes it to the TBC format in CVBS or S-Video.
 * ld-disc-stacker - Image frame stacking for the .TBC files.
 * ld-dropout-correct does dropout correction on a single TBC file or stacks data from multiple files to composite a cleaner file.

Related Tools:
 * ld-lds-converter - Converts 10-Bit packed captures to 16-bit signed used to unpack to file or in realtime for ld-compress
 * ld-ldf-cut - allows for cutting of RF data files
 * ld-compress - Compresses 10-bit/16-bit FM RF data into a FLAC file saving 30~60% space.


 * tbc-video-export - (Linux/Windows/MacOS) Exports video files from single or tbc file pairs, and runs ld-dropout-correct/ld-process-vbi and ld-chroma-encoder with FFmpeg to make a final video file. (.py & .exe tool)
 * gen_chroma_vid.sh - (Linux/MacOS) Exports a FFV1 4:2:2 10-bit video file, first script made for duel tbc file export. (.sh script)

LD-Analyse (TBC Analysis & Adjustment Tool)
LD-Analyse the primary application for viewing the TBC files directly allows for frame by frame inspection of the whole active image area and vertical blanking area, simmer to a H/V shift capable broadcast CRT's (Sony PVM/BVM etc) the whole signal area is available, and aspect ratios such as 1:1 SAR, DAR 4:3 & 16:9 can be defined, with dropouts being visually displayed with an overlay using red/blue colours on the effected lines of analogue video.

As shown with the set of images above and to the right side there is visual information and its relating graphing data of white and black signal to noise ratio and dropouts can be also viewed, there is also a vector-scope and scan-line oscilloscope Chroma colour decoding and video levels data can be changed on the fly inside ld-analyse to then be adjusted on the single command encoding to a final video file.

LD-Analyse ability's

 * Vector-Scope
 * Scan-Line Oscilloscope
 * Visual Dropout Display
 * FTT Visulisation Overlay
 * Black & White Video Level Adjustment
 * PNG Image Export

Source (GitHub) References

 * CVBS-Decode (Composite Decoding) - 2022
 * VHS-Decode (Tape Decoding) Wiki - 2022
 * LD-Decode (LaserDisk Decoding) Wiki - 2022
 * TBC-Analogue (FL2K) - 2022

Technical References

 * Domesday86 - 2022
 * JSON Metadata Format ld-decode-wiki - 2022


 * Digital Video and HD: Algorithms and Interfaces by Charles Poynton - 2012