extract-frames

Extracting frames from videos

Use Mediabunny to extract frames from videos at specific timestamps. This is useful for generating thumbnails, filmstrips, or processing individual frames.

The extractFrames() function

This function can be copy-pasted into any project.

import {
  ALL_FORMATS,
  Input,
  UrlSource,
  VideoSample,
  VideoSampleSink,
} from "mediabunny";

type Options = {
  track: { width: number; height: number };
  container: string;
  durationInSeconds: number | null;
};

export type ExtractFramesTimestampsInSecondsFn = (
  options: Options
) => Promise<number[]> | number[];

export type ExtractFramesProps = {
  src: string;
  timestampsInSeconds: number[] | ExtractFramesTimestampsInSecondsFn;
  onVideoSample: (sample: VideoSample) => void;
  signal?: AbortSignal;
};

export async function extractFrames({
  src,
  timestampsInSeconds,
  onVideoSample,
  signal,
}: ExtractFramesProps): Promise<void> {
  using input = new Input({
    formats: ALL_FORMATS,
    source: new UrlSource(src),
  });

  const [durationInSeconds, format, videoTrack] = await Promise.all([
    input.computeDuration(),
    input.getFormat(),
    input.getPrimaryVideoTrack(),
  ]);

  if (!videoTrack) {
    throw new Error("No video track found in the input");
  }

  if (signal?.aborted) {
    throw new Error("Aborted");
  }

  const timestamps =
    typeof timestampsInSeconds === "function"
      ? await timestampsInSeconds({
          track: {
            width: videoTrack.displayWidth,
            height: videoTrack.displayHeight,
          },
          container: format.name,
          durationInSeconds,
        })
      : timestampsInSeconds;

  if (timestamps.length === 0) {
    return;
  }

  if (signal?.aborted) {
    throw new Error("Aborted");
  }

  const sink = new VideoSampleSink(videoTrack);

  for await (using videoSample of sink.samplesAtTimestamps(timestamps)) {
    if (signal?.aborted) {
      break;
    }

    if (!videoSample) {
      continue;
    }

    onVideoSample(videoSample);
  }
}