`laserdisc`¶

Everything about a project that is specific to LaserDisc (LaserVision): the disc format, the LaserVision signal options, EFM digital audio and the LaserVision replay channel. Optional — a project that is not a disc has no laserdisc: block, and none of these settings appear anywhere else in the file.

laserdisc:
  disc_type: CAV
  pilot_burst: true
  efm_audio:
    pair: 0
  channel:
    fm_beat:
      level_db: -24.0
    group_delay:
      preset: iec60856_nominal

Each section that belongs to the disc says where it sits on it, and which biphase codes it carries, in its own section laserdisc block.

Keys¶

Key	Type	Required	Values	Default
`disc_type`	string	No	`CAV`, `CLV`	absent (no disc addressing)
`pilot_burst`	bool	No	`true`, `false`	`false`
`vbi_burst`	bool	No	`true`, `false`	`false`
`efm_audio`	map	No	See `efm_audio`	absent
`channel`	map	No	See LaserVision channel	absent

The block must set at least one key. An empty laserdisc: block, or any other key, is a parse error.

SECAM projects cannot have the block: there is no SECAM LaserVision format (IEC 60856 defines PAL discs only).

`disc_type`¶

The disc format for the whole project. A disc is entirely one or the other, which is why it is project-wide and is not repeated on each section.

Value	Addressing
`CAV`	Picture number — one frame per track
`CLV`	Programme time code plus CLV picture number

It determines which code_type values the validator accepts, and setting it turns on the disc VITS rules (reserved address-code lines, and VIRS on NTSC/PAL-M — see line_injections) whether or not any section carries codes. It is required as soon as any section carries biphase codes. A project with no biphase codes — an EFM-only disc, or a pilot-burst test — can leave it out.

`pilot_burst`¶

Superimposes a 3.75 MHz (240 × f_H) sinusoidal burst at ±300 mV on every sync pulse in the luma channel — IEC 60856 §9.1.2.

PAL only. Enabling it on an NTSC or PAL-M project is a validation error.

Warning: with CVBS_U10_4FSC, CVBS_U16_4FSC or CVBS_TPG21_4FSC the burst trough is clipped at −300 mV, where the waveform reaches −600 mV. Use CVBS_S16_4FSC or a raw preset.

`vbi_burst`¶

Keeps the colour burst on every line of the vertical interval, including the equalising and broad field-sync lines (lines 1–9 and 264–272) where standard NTSC suppresses it — IEC 60857 §9.1.2 and Figure 6a. Each burst is the normal NTSC burst: same gate position after 0H, amplitude and continuous subcarrier phase. On the broad field-sync lines the gate falls inside the broad pulse, so the burst is centred on sync tip.

NTSC only. Enabling it on a PAL or PAL-M project is a validation error.

Warning: with CVBS_U10_4FSC, CVBS_U16_4FSC or CVBS_TPG21_4FSC the colour burst on the broad field-sync pulses is clipped at sync tip (−40 IRE), where the waveform reaches −60 IRE. Use CVBS_S16_4FSC or a raw preset.

`efm_audio`¶

Its presence enables LaserDisc EFM digital audio output for one channel pair. Omit the key to disable.

PAL uses the 625-line definition of IEC 60856 Amd 2 clause 13. NTSC and PAL-M use the 525-line definition of IEC 60857 Amd 2 clause 13: no LaserVision standard names PAL-M, and a PAL-M disc is a 525-line disc at the NTSC frame rate, so it takes the NTSC sample sequence and identifies as a 525-line disc in its table of contents.

Key	Type	Required	Range
`pair`	int	Yes	0–7

Constraints:

Rule	Severity
`pair` in 0–7	Error
At most 79 `programme_area` sections (one EFM track each)	Error
No section declares `pair` — nothing to encode, no `.efm` written	Warning
A `programme_area` section under 4 s (6 s for the first)	Warning
No `lead_in` section, so no table of contents	Warning

The disc areas come from each section's laserdisc.area: a lead-in carries the table of contents, each programme-area section is one EFM track and the lead-out carries lead-out subcode. The pair's tone parameters are declared only in the per-section audio: blocks; its 48 kHz WAV track is written as normal and is unaffected. The .efm and .efm.meta files are written beside the video output — see output and Audio.

`channel`¶

The LaserVision pressing and replay channel: the FM-beat herringbone recorded on the master, the group-delay pre-distortion of IEC 60856, the replay amplitude response (fixed, or varying with disc position) and the misregistration of field 2 against field 1. See LaserVision channel.

Rules¶

An empty block, an unknown key, a non-string disc_type, a non-boolean pilot_burst or vbi_burst, or a non-integer efm_audio.pair is a parse error.
disc_type other than CAV or CLV is a validation error, as is a section with biphase codes in a project without disc_type.
A section with a laserdisc block in a project without one is a validation error.
The whole block on a SECAM project is a validation error.

LaserDisc keys in other blocks¶

The LaserDisc settings are accepted only in the laserdisc blocks. Each of these keys is a parse error in the other blocks, and the error names the key to use instead:

Rejected key	Use instead
`cvbs_presets.pal_laserdisc_pilot_burst`	`laserdisc.pilot_burst`
`cvbs_presets.ntsc_laserdisc_vbi_burst`	`laserdisc.vbi_burst`
`output.efm_audio`	`laserdisc.efm_audio`
`line_injections.disc_type`	`laserdisc.disc_type`
`channel.fm_beat`	`laserdisc.channel.fm_beat`
`sections[].section_type`	`sections[].laserdisc.area`
`sections[].line_injections` entry with `type: laserdisc`	`sections[].laserdisc.codes`

cvbs_presets.pal_laserdisc_pilot_burst has moved to laserdisc.pilot_burst.

scripts/migrate_laserdisc_keys.py rewrites project files that use these keys in place, keeping their comments and layout:

python3 scripts/migrate_laserdisc_keys.py --check projects/*.yaml   # list what would change
python3 scripts/migrate_laserdisc_keys.py projects/*.yaml           # rewrite

It expects block-style YAML as the emitter writes it, and leaves alone (with a message) any file whose layout it does not recognise. Comments that mention the rejected keys are not rewritten.

laserdisc¶

Keys¶

disc_type¶

pilot_burst¶

vbi_burst¶

efm_audio¶

channel¶