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Data fetching

One of the coolest things about Remotion is that you can fetch data from an API.

It works almost like you are used to: You can use the fetch API to load data in a useEffect() call and set a state.

Telling Remotion to wait until the data is loaded​

There are two functions, delayRender and continueRender, which you can use to tell Remotion to not yet render the frame. If you want to asynchronously render a frame, you should call delayRender() as soon as possible, before the window onload event is fired. The function returns a handle that you need to give Remotion the green light to render later using continueRender().

tsx
import { useCallback, useEffect, useState } from "react";
import { continueRender, delayRender } from "remotion";
 
export const MyVideo = () => {
  const [data, setData] = useState(null);
  const [handle] = useState(() => delayRender());
 
  const fetchData = useCallback(async () => {
    const response = await fetch("http://example.com/api");
    const json = await response.json();
    setData(json);
 
    continueRender(handle);
  }, [handle]);
 
  useEffect(() => {
    fetchData();
  }, [fetchData]);
 
  return (
    <div>
      {data ? (
        <div>This video has data from an API! {JSON.stringify(data)}</div>
      ) : null}
    </div>
  );
};
tsx
import { useCallback, useEffect, useState } from "react";
import { continueRender, delayRender } from "remotion";
 
export const MyVideo = () => {
  const [data, setData] = useState(null);
  const [handle] = useState(() => delayRender());
 
  const fetchData = useCallback(async () => {
    const response = await fetch("http://example.com/api");
    const json = await response.json();
    setData(json);
 
    continueRender(handle);
  }, [handle]);
 
  useEffect(() => {
    fetchData();
  }, [fetchData]);
 
  return (
    <div>
      {data ? (
        <div>This video has data from an API! {JSON.stringify(data)}</div>
      ) : null}
    </div>
  );
};

Best practices​

During rendering, multiple tabs are opened to speed up rendering. In each of these tabs, the tree is re-rendered by changing the value of useCurrentFrame() and then screenshotted.

  • Each tab will execute the data fetching individually, so if you are rendering with a high concurrency, you may run into a rate limit.
  • You can use the localStorage API to persist data after a network request and make a request only if the local storage is empty.
  • The data returned by an API must be the same when called multiple times, otherwise flickering may apply.
  • Consider fetching data before the render, and pass data as input props
  • Make sure to not have frame as a dependency of the useEffect(), otherwise data will be fetched every frame leading to slowdown and potentially running into rate limits.

Time limit​

You need to clear all handles created by delayRender() within 30 seconds after the page is opened. You may increase the timeout.

Using delayRender() to calculate video metadata​

You can also customize duration, frame rate and dimensions based on asynchronous data fetching:

See also​