File & Data Formats

RF Formats

CXADC 16-bit Unsigned

CXADC 08-bit Unsigned

DDD 10-bit Packed (10-bit unsigned integers)

DDD 16-bit Signed

Context of Extension Formats

.lds - DDD 10-bit Packed or 16-bit Signed 40msps

.ldf - FLAC Compressed 16-bit 40msps (DomesDayDuplicator)

.cds - 10-bit Packed 10msps (4:1 decimation mode)

.s16 - Uncompressed Signed 16-bit (40msps DomesDayDuplicator)

.u8/.r8 - CXADC 08-bit Unsigned

.u16.r16 - CXADC 16-bit Unsigned

.vhs - FLAC Compressed VHS 8-bit or 16-bit

.svhs - FLAC Compressed S-VHS 8-bit or 16-bit

.cvbs - FLAC Compressed CVBS 8-bit or 16-bit

.flac/.wav/.raw can also be used but would need file name context.

The decoder accepts RF data in 10-bit packed 8-bit raw and 16-bit raw sample formats and FLAC compressed bitdepth is automatic.

Decoder sample rate is 40msps defacto, anything diffrent has to be disciminated via -f input 16/20 etc etc

Archives have been standerdised to 40msps / 20msps / 16msps

TBC Data Output Formats

filename.tbc - Luminance Image Data

filename_chroma.tbc - Chrominance Image Data

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

filename.log - Timecode Indexed Action/Output Log

The TBC Format

TBC Acronym, Time Base Corrected .TBC is a lossless digital file format containing time base corrected digtised analouge signals.

A TBC retimes a video signal to make video lines (like a shreadded peice of paper) more accurately the same length i.e correcting the time base of each line/field this fixes wobbly or skied images as observed on lower-end VCRs the lines vary in length across the picture.

Decodes TBC is not a frame store so what you get is what you get dropped frames just dont exist anymore.

In a stable tape workflow a TBC acts as a buffer and conforms signal output to a stable broadcast equipment acceptable one this process can also check the chroma phase so colour is accuractly displayed and do dropout correction based off RF signal level drops.

Decodes TBC does not do drop out correction inside the TBC process, however it does gather data for doing that afterwards with the chroma-decoder and is on by defualt.

The TBC file is created by the RF decoder directly after the signal de-modulation.

Decoding takes the 2 channels chrominance and luminance (C & Y) and creates separate TBC files for each respectively this allows for very clinical post adjustments and the ability to remove Croma entirely if unstable and or source is black and white media for example.

Technical Data Stream Information

The format is a stream of 16-bit unsigned values; each value representing a single grey-scale value in a header-less data file.

Header-less data files are very resilient data i.e power loss or system issue and bit curruption will only damge or lose few frames of information.

So you end with a composite 4fsc "full-frame" digital video file of the video signal.

PAL Is Full 4fsc 1135x625 (17727262 hz) 16-bit values.

NTSC Is Full 4fsc 525x910 (14318181 hz) 16-bit values.

The 16-bit greyscale values used by the output format are scaled representations of the standard 8-bit digital component values i.e. an 8-bit right shift of the value will provide the standard 8-bit digital component intensity values.

Sample rate is always 4fsc, it's just stored a little weird in the .tbc for convenience: a 526th empty line in NTSC and a 626th line in PAL that has 4 samples - 2 from each field.

Gen Croma Scripts & Chroma-Decoder

The gen Croma .sh scripts do several things, dropout compensation, combine Croma & Luma TBC's to create a full-colour video stream there is also dropout compensation in this step but can be done separately in the ld-tools segment allowing for multi-stage metadata extraction or even stacking to compensate for normal operation dropouts.

To encode a black and white luminance only video use the chroma decoder

ld-chroma-decoder tapename.tbc y4m OutputName.mov (-p - PAL or -n for NTSC)

This gives you an uncompressed YUY 4:2:2 video file

./gen_chroma_vid.sh tapename.tbc -f OutputName.mov

This gives you a Lossless Compressed FFV1 YUY 4:2:2 encoded file in the .mkv container.

Standard output is 70-80mbps

Full Frame output is 100-130mbps

Note! the experimental full 1135x625 PAL 910x525 NTSC output currently has issues with frame order and it's a few pixels off this will be improved in the future.