remotion-dev/remotion · error · Error

Expected width segment

Error message

Expected width segment

What it means

Thrown by `getTrack` (make-track.ts:282) for a video track whose TrackEntry has no `PixelWidth` element (`getWidthSegment` returns null). PixelWidth is mandatory for video tracks in Matroska; without it the coded/display width is unknown and the track object cannot be constructed.

Source

Thrown at packages/media-parser/src/containers/webm/make-track.ts:282

	timescale,
	track,
}: {
	timescale: number;
	track: TrackEntry;
}): MediaParserVideoTrack | MediaParserAudioTrack | null => {
	const trackType = getTrackTypeSegment(track);

	if (!trackType) {
		throw new Error('Expected track type segment');
	}

	const trackId = getTrackId(track);

	if (trackTypeToString(trackType.value.value) === 'video') {
		const width = getWidthSegment(track);

		if (width === null) {
			throw new Error('Expected width segment');
		}

		const height = getHeightSegment(track);

		if (height === null) {
			throw new Error('Expected height segment');
		}

		const displayHeight = getDisplayHeightSegment(track);
		const displayWidth = getDisplayWidthSegment(track);

		const codec = getCodecSegment(track);
		if (!codec) {
			return null;
		}

		const codecPrivate = getPrivateData(track);
		const codecString = getMatroskaVideoCodecString({

View on GitHub (pinned to 78fe4bb3fd)

Solutions

1. Re-mux/re-encode so dimensions are recorded: `ffmpeg -i in.webm -c copy out.webm`.
2. Verify with `ffprobe` — missing PixelWidth typically breaks it too.
3. Reject the corrupt asset upstream; catch the parse error and degrade.

// Verify the video stream reports dimensions before parsing.
import { execFile } from 'node:child_process';
import { promisify } from 'node:util';
const exec = promisify(execFile);
async function hasDimensions(filePath) {
  const { stdout } = await exec('ffprobe', ['-v', 'error', '-select_entries', 'stream=width,height', '-of', 'json', filePath]);
  const info = JSON.parse(stdout);
  return info.streams?.some((s) => s.width && s.height) ?? false;
}

try {
  await parseMedia({ src, fields: { tracks: true } });
} catch (err) {
  if (err instanceof Error && err.message === 'Expected width segment') {
    console.warn('Video TrackEntry missing PixelWidth — malformed file:', src);
    return null;
  }
  throw err;
}

When it happens

Trigger: A video TrackEntry missing `PixelWidth`. Truncated/corrupt headers, non-conformant muxers, or files where the video element block was written before dimensions were finalized.

Common situations: Interrupted encodes; corrupt MKV/WebM video track headers; rare muxer bugs. Files that play elsewhere virtually always carry PixelWidth.

Related errors

• Expected height segment
• Expected track entry segment
• Expected codec segment
• Expected track type segment
• Expected av1 private data to be version 1

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/a1fb6c027c88e466. Report an issue: GitHub.