A/V Sync Sender

A/V Sync Sender input properties for Script Engine. Generates the reference signal for measuring audio/video sync. Every frame carries one of nine states, stamped onto the picture as a flat colour field and onto the sound as a pair of tones. Feed it through whatever path you want to test - a target and back in, or just down the local layer chain - and put an A/V Sync Receiver at the far end to read the offset back. This is a measuring instrument, not a production source. Both halves of every frame are written in one pass keyed on the engine's frame index, so picture and sound leave here in exact step by construction; anything the receiver measures was introduced downstream.

Property	Type	Access	Description
`AutoStart`	`bool`	`get/set`	Whether the sender starts producing output as soon as the project loads. [default=true].
`MatchSceneResolution`	`bool`	`get/set`	Whether the picture is sized automatically to cover the scene. [default=true]. A source smaller than the scene is composited at its native size, leaving scene background around it - and a receiver measures an area of the frame, so any background caught in that area drags every colour towards black and the states stop being identifiable. The black state still matches, which shows up as a decode rate of about one in nine. Leaving this on avoids the whole problem. Turn it off to drive `Width` and `Height` yourself.
`Width`	`int`	`get/set`	Width of the generated picture, in pixels. [min=16, max=8192, default=1280]. Ignored while `MatchSceneResolution` is on. The field is flat, so its size costs almost nothing.
`Height`	`int`	`get/set`	Height of the generated picture, in pixels. [min=16, max=8192, default=720]. Ignored while `MatchSceneResolution` is on.
`FullLevelDb`	`int`	`get/set`	Level of a "full" tone, in dBFS. [min=-20, max=0, default=-1]. The half-level states sit 6 dB below this. The default backs off 1 dB from full scale so a nominally-full tone does not clip an encoder on the way out; the receiver judges levels relative to the loudest channel it sees, so lowering this does not upset the measurement.
`PlaybackState`	`PlaybackState`	`get`	Current playback state of the sender (read-only). Reflects whether the input is `Stopped` or `Running`. Set indirectly via `StartCommand` / `StopCommand`, or by `AutoStart` at load time.
`StartCommand`	`Command`	`get`	Begin generating the test signal. Invokable command. Transitions `PlaybackState` to `Running` and restarts the state cycle from a clean phase. No-op if already running.
`StopCommand`	`Command`	`get`	Stop generating the test signal. Invokable command. Transitions `PlaybackState` to `Stopped` and silences the audio, so a receiver downstream drops out of lock rather than holding its last reading.
`CurrentState`	`int`	`get`	The state number stamped onto the most recent frame, 0-8 (read-only). Both the picture and the sound of that frame carry this number.
`FramesGenerated`	`int`	`get`	Number of frames generated since the last start (read-only).

Inherits from: AbstractInput, AbstractAudioProcessing, AbstractAudioMetering, NamedModel.

See also: A/V Sync Sender in Inputs — user-facing introduction, screenshots, and section summaries.