Thumbnails

createThumbnail(inputUri, options?): Promise<ThumbnailResult> independently writes a JPEG, returning { path: string, width: number, height: number }. path is an absolute cache path; dimensions describe the actual JPEG with source orientation applied.

time is a finite value from 0–2147483 seconds and must be before source end. JPEG dimensions retain aspect ratio without upscaling and do not use the video's even-pixel rule. Numeric JPEG quality is different from compression preset names. JPEG has no transparency.

import {
  createThumbnail,
  getVideoMetadata,
} from "react-native-media-transformer";

export async function makeVideoPreview(inputUri: string) {
  const video = await getVideoMetadata(inputUri);
  const image = await createThumbnail(inputUri, {
    time: Math.min(1, video.duration / 2),
    maxWidth: 480,
    maxHeight: 320,
    quality: 0.8,
  });
  return { video, image, imageUri: `file://${image.path}` };
}

Call this helper with an accepted video URI and handle its returned promise's rejection. For a trimmed output, the thumbnail timestamp is relative to that output clip, not the original timeline. The decoder chooses a frame at or near the timestamp; exact-frame selection is not guaranteed and some timestamps can reject.