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renderFrames()

Part of the @remotion/renderer package.

Renders a series of images using Puppeteer and computes information for mixing audio.

const renderFrames: (options: {
config: VideoConfig;
compositionId: string;
onFrameUpdate: (frame: number) => void;
onStart: (data: {
frameCount: number;
}) => void;
outputDir: string;
inputProps: unknown;
webpackBundle: string;
imageFormat: "png" | "jpeg" | "none";
envVariables?: Record<string, string>;
parallelism?: number | null;
quality?: number;
frameRange?: number | [number, number] | null;
dumpBrowserLogs?: boolean;
puppeteerInstance?: puppeteer.Browser;
onError?: (info: {error: Error; frame: number | null}) => void;
}): Promise<RenderFramesOutput>;
info

Configuration in remotion.config.ts and CLI flags do not apply to this function. You must pass all options explicitly.

Arguments#

Takes an object with the following keys:

config#

A video config, consisting out of width, height, durationInFrames and fps. See: Defining compositions and useVideoConfig().

compositionId#

A string specifying the ID of the composition. See: Defining compositions.

onStart#

A callback that fires after the setup process (validation, browser launch) has finished. Example value

const onStart = () => {
console.log('Starting rendering...');
}

onFrameUpdate#

A callback function that gets called whenever a frame finished rendering. An argument is passed containing how many frames have been rendered (not the frame number of the rendered frame). Example value

const onFrameUpdate = (frame: number) => {
console.log(`${frame} frames rendered.`)
}

outputDir#

A string specifying the directory (absolute path) to which frames should be saved.

inputProps#

Custom props which will be passed to the component. Useful for rendering videos with dynamic content. Can be an object of any shape.

webpackBundle#

A string specifying the location of the bundled Remotion project.

imageFormat#

A string which must be either png, jpeg or none.

  • Choose jpeg by default because it is the fastest.
  • Choose png if you want your image sequence to have an alpha channel (for transparency).
  • Choose none if you only want to render audio.

parallelism?#

optional

A number specifying how many frames should be rendered in parallel or null to let Remotion decide based on the CPU of the host machine. Default is half of the CPU threads available.

quality?#

optional

Sets the quality of the generated JPEG images. Must be an integer between 0 and 100. Default is to leave it up to the browser, current default is 80.

Only applies if imageFormat is 'jpeg', otherwise this option is invalid.

frameRange?#

optional

Specify a single frame (passing a number) or a range of frames (passsing a tuple [number, number]) to be rendered. By passing null (default) all frames of a composition get rendered.

dumpBrowserLogs?#

optional

Passes the dumpio flag to Puppeteer which will log all browser logs to the console. Useful for debugging. boolean flag, default is false.

puppeteerInstance?#

optional

An already open Puppeteer Browser instance. Reusing a browser across multiple function calls can speed up the rendering process. You are responsible for opening and closing the browser yourself. If you don't specify this option, a new browser will be opened and closed at the end.

envVariables?#

optional - Available since v2.2.0

An object containing key-value pairs of environment variables which will be injected into your Remotion projected and which can be accessed by reading the global process.env object.

onError?#

optional - Available since v2.1.0

Allows you to react to an exception thrown in your React code. The callback has an argument which is an object containing error and frame properties. The frame property tells you at which frame the error was thrown. If the error was thrown at startup, frame is null.

renderFrames({
onError: (info) => {
if (info.frame === null) {
console.log('Got error while initalizing video rendering', info.error)
} else {
console.log('Got error at frame ', info.frame, info.error)
}
// Handle error here
}
})

Return value#

A promise resolving to an object containing the following properties:

  • frameCount: number - describing how many frames got rendered.
  • assetsInfo: RenderAssetInfo - information that can be passed to stitchFramesToVideo() to mix audio. The shape of this object should be considered as Remotion internals and may change across Remotion versions.

See also#