This spin-off project uses RAW CVBS captures and uses the signal processing and time base correction code, from vhs-decode & ld-decode there is no de-modulation like FM media.

CVBS an abbreviation,

Composite Video Baseband Signal. (also lesser used: colour, video, blanking, and sync)

Baseband means a de-modulated signal off a recorded medium or a non-modulated live signal directly off a camera or media generation device.

Baseband signals are ready for direct use for audio this means a speaker and for video used to be an analogue analogue CRT TV set now its all on analogue to digital converter ICs.

Composite analogue video signals have been used from the pre-digital era to early digital equipment, developed in the 1950s and in full use from the 1960s to even today analogue systems using the ''Yellow RCA jack'' on consumer equipment and a BNC jack on prosumer/broadcast equipment.

S-Video is just composite Luminance with the Chromance modulated this minimizes colour interference during transport inside a cable with a pair of 2 shield cables shielded S-Video cable or 2 separate BNC cables then the chroma is demodulated at the input device level, there are 3 versions of this standard.

MISRC Has support for native RAW Composite/CVBS and S-Video capture in 12-bit (16-bit 40msps singed or unsigned samples).

CX Cards can try to switch back into standard mode causing wavy, jiggling, and loss of vertical sync frames, however if the card is in a fixed low gain state (level 0 / sixdb off) it is possible to get clean stable captures.

The DomesDayDuplicator's input filtering is not suited for said signal range, the input filtering stage needs to be modified currently, this does not work well as it captures the signal improperly.

There is also using a T adaptor to feed a secondary signal via waveform generator to keep CX Cards in raw output mode, then in post to low pass filter it and then decode it.

cvbs-decode is included inside the vhs-decode install, and is ready to go on self contained builds.

However for Linux you might need to do:

python3 setup.py build_ext --inplace

That's it you are ready to use CVBS-Decode!

Currently, this decoder will work just fine with stable signals and live media.

Example Usage Command:

cvbs-decode --debug --pal -A --cxadc composite-test_28msps_8-bit.u8 composite-test

To stop the decode press Ctrl+C

cvbs-decode only outputs 3 files

filename.tbc - 4fsc Luminance & Chrominance Image Data

filename.tbc.json - Frame Descriptor Table (Resolution/Dropouts/SNR/Frames/VBI Data)

filename.log - Timecode Indexed Action/Output Log

ld-analyse composite.tbc

The TBC-Video-Export tool will automatically detect NTSC/PAL input, it can also run ld-dropout correct & ld-process-vbi and will embed the updated .json file inside the mkv, and export a FFV1 10-bit 4:2:2 interlaced file, read the wiki doc for detailed use of its profiles.

Linux & MacOS:

tbc-video-export composite-test.tbc

Windows:

tbc-video-export.exe composite-test.tbc

Click the here for the full list, the below are just basic usage commands only.

Just like vhs-decode & ld-decode the default is 40msps 8-bit/10-bit/16-bit input.

Captures can be FLAC compressed (.cvbs) or Uncompressed .u8/u16 etc

-f Frequency Adjust in integers of hz, mhz, ghz or 4fsc/5fsc/8fsc/10fsc

--cxadc 28.6 MHz/8-bit (8fsc) Stock Crystal Native 8xFsc 8bit Unsigned Sampling Mode

--cxadc3 35.8 MHz/8-bit (10fsc) Stock Crystal Native 4xFsc 16bit Filtered Vertical Blanking Interval Data (Not Recommended for capture due to up-sampling)

--10cxadc 14.3 MHz/16-bit (4fsc) Stock Crystal 1.25x 8xFsc 8bit Unsigned Sampling Mode

--10cxadc3 17.9 MHz/16-bit (5fsc) Stock Crystal 1.25x 4xFsc 16bit Filtered Vertical Blanking Interval Data

-n NTSC

--NTSCJ NTSC-J

-p PAL

--pm PAL-M

--debug Enables debug detailed logging output.

-A Automatic Sync Detection (Currently Mandatory For CVBS-Decode to work)

-S Seek Frame of Capture

--right_hand_hsync Use right-hand horizontal sync detection.

--ct Chroma Trap, cleans up chroma interference on the luma channel.

--sl Defines sharpness by default this is set to 0. (0-100 Range)

--notch Define the centre frequency for the optional built-in notch "bandpass" filter.

--notch_q defines the Q factor Intended primarily for reducing noise from interference however, the decoder logic already compensates based on tape type and TV System values.

The Composite signal is stored in a single .tbc

This is a lossless digital file of the entire baseband composite signal like a D2/D3 digital tape.

Full 4fsc 1135x625 PAL (17727262 hz) (25i) (4.2GB/min) (560mbps)

Full 4fsc 910x525 NTSC (14318181 hz) (29.97i) (3.4GB/min) (453mbps)

• Chroma issues with NTSC VHS use ntsc-phase-comp with chroma-decoder.

• CVBS-Decode is not like ld-decode or vhs-decode so highly unstable sources will most likely require tinkering.