FrameRecorder

class FrameRecorder

import { FrameRecorder } from '@driftengine/core';

Constructor

`new`

constructor(options: FrameRecorderOptions)

Parameter	Type	Description
`options`	`FrameRecorderOptions`

Accessors

Name	Type	Description
`mimeType`get	`string`
`pacing`get	`FramePacingReport \| null`	What the pacing actually was, or null when recording the canvas directly. More The measurement is the point rather than a diagnostic afterthought: an export that ran below its target rate produced a juddering file, and the only honest options are to say so or to have not measured.
`duplicateFrame`get	`boolean`	Whether the frame `frameRendered` just composited repeats the one before it. More False without a target, and false when `presentedFrames` was never supplied — the same two "no evidence yet" cases `pacing` already has to account for. See `ExportTarget.duplicateFrame`, which this only forwards.

Methods

`prepare`

prepare(): { width: number; height: number; reduced: boolean; } | null

Take over the render surface before recording starts.

Separate from start because the aspect has to be in force before the first frame anybody records: the camera composes for renderer.aspect, so locking and recording in the same breath would put a screen-shaped shot in the first frames of a vertical clip. Returns the frame size that will be recorded, which is not always the one requested — see measuredFps.

`captureDue`

captureDue(nowMs: number): boolean

Whether the frame about to be drawn will be kept. True when there is no fixed target, so a caller can gate its render pass unconditionally.

Parameter	Type	Description
`nowMs`	`number`

Call once per animation frame, drawing or not: the instant is kept and reused when the frame is handed over, so one clock decides and commits.

`frameRendered`

frameRendered(): boolean

One rendered frame, offered to the recording.

Call at the very end of the render pass. Cheap and false when there is no fixed target, so a caller can hand every frame over unconditionally. Takes no instant — it uses the one captureDue was given for this frame.

`resetPacing`

resetPacing(): void

Start the measurement over, keeping the schedule.

For a caller that records a warm-up in front of the clip proper: what a device costs while an encoder gets going is not what the clip is like, and the report is what the export decides whether to warn the player on.

`start`

start(): void

`stop`

stop(): Promise<Blob | null>

Resolves with the finished clip, or null if nothing was recorded.

The surface goes back before the promise resolves either way. A cancelled export that left the drawing buffer pinned to 1080x1920 would leave the game rendering into the wrong shape for the rest of the session.

`release`

release(): void

Give the render surface back. Safe at any point, and idempotent.