cvbs_presets

The signal format for the whole project. Required. There are no per-section overrides — a capture file has one format.

cvbs_presets:
  video_standard_preset: PAL
  sample_encoding_preset: CVBS_S16_4FSC
  signal_state_preset: STANDARD_STABLE_LOCKED

Keys

Key	Type	Required	Values	Default
video_standard_preset	string	Yes	PAL, NTSC, PAL_M, SECAM	—
sample_encoding_preset	string	No	See below	CVBS_U10_4FSC
signal_state_preset	string	No	STANDARD_STABLE_LOCKED; STANDARD_STABLE_UNLOCKED for SECAM	Per standard (see below)
ntsc_black_setup_ire	float	No	7.5, 0.0	7.5
secam_field_identification	bool	No	true, false	true

No other key is accepted. In particular there are no mode, field_order, field_dominance or endianness keys — field order and dominance follow the standard, and sample data is little-endian. The LaserDisc signal options — the PAL pilot burst and the NTSC VBI burst — are in the laserdisc block.

video_standard_preset

Value	Lines	Frame rate	Subcarrier	Raster
PAL	625	25 fps	4.43361875 MHz	720×576
NTSC	525	30000/1001 fps	3.579545 MHz	720×486
PAL_M	525	30000/1001 fps	3.575611 MHz	720×486
SECAM	625	25 fps	4.40625 MHz (D′R) / 4.25 MHz (D′B), frequency modulated	720×576

PAL-M is accepted as a spelling of PAL_M.

SECAM has the same line and field timing, signal levels, active raster and 4fsc storage lattice as PAL; only the colour encoding differs. It has no single colour subcarrier, so the CVBS file format adopts the PAL 4fsc rate as its standard rate (CVBS File Format Specification, Preset: SECAM). See SECAM chroma for what is generated.

Only one standard per project. The output resolution follows from it and must not be specified anywhere in the file.

sample_encoding_preset

Value	Rate	Sample format
CVBS_U10_4FSC	4fsc	Unsigned, 10-bit codes
CVBS_U16_4FSC	4fsc	Unsigned 16-bit
CVBS_TPG21_4FSC	4fsc	Signed 16-bit, offset and scaled about mid-code
CVBS_S16_4FSC	4fsc	Signed 16-bit relative to blanking; preserves sub-sync excursions
RAW_S16_28M	28 MHz	Signed 16-bit millivolts, resampled from 4fsc
RAW_S16_40M	40 MHz	Signed 16-bit millivolts, resampled from 4fsc

4fsc rates are 17,734,475 Hz (PAL and SECAM) and 14,318,180 Hz (NTSC/PAL-M). Frames are 709,379 samples (PAL and SECAM) and 477,750 samples (NTSC/PAL-M).

Rule: 4fsc generation requires a 4fsc encoding and the signal_state_preset the standard requires (see below).

The LaserDisc pilot burst and VBI burst reach below sync tip, so they need CVBS_S16_4FSC or a raw preset to survive unclipped.

signal_state_preset

Standard	Required value
PAL, NTSC, PAL_M	STANDARD_STABLE_LOCKED
SECAM	STANDARD_STABLE_UNLOCKED

STANDARD_STABLE_LOCKED means standard 4×fsc sample rate, time-base stable, and phase locked — the content is sampled at the standard subcarrier-reference-locked phase points, which synthetic generation satisfies by construction.

SECAM chrominance is frequency modulated, so its subcarrier phase depends on picture content and the CVBS file format defines no Sc/H convention for it. A SECAM file must not be declared phase locked; generated SECAM output is time-base stable at the standard rate and is declared STANDARD_STABLE_UNLOCKED.

When the key is omitted, the required value for the standard is used. Any other value is rejected: the remaining presets describe captures that are unstable or at a non-standard rate, which videosynth never produces.

Because the generated signal is one unbroken sequence — subcarrier phase and colour field sequence advance continuously with the output frame position — the metadata file always declares sequence_continuous = TRUE (see outputs).

ntsc_black_setup_ire

Value	Effect
7.5	Standards-based NTSC setup — black sits 7.5 IRE above blanking
0.0	Black at blanking (0 IRE), as in Japanese NTSC and digital-origin material

NTSC and PAL-M only. Specifying it on a PAL or SECAM project is a validation error, and any value other than 7.5 or 0.0 is rejected.

Project configuration error: ntsc_black_setup_ire can only be specified for
NTSC or PAL-M projects.

secam_field_identification

Emits the SECAM field identification signals ("bottles") on lines 7–15 and 320–328 — ITU-R BT.1700 Annex 1 Part C Table 4 item 13. Only meaningful with video_standard_preset: SECAM; set it to false to generate line identification only. Setting it to false on another standard is accepted but produces a warning:

secam_field_identification has no effect unless video_standard_preset is SECAM.