remotion-dev/remotion · error · Error

Unsupported TRUN version ${version}

Error message

Unsupported TRUN version ${version}

What it means

The TRUN (Track Run) box parser only supports versions 0 and 1; any other version byte throws. TRUN v0 and v1 are the spec-standard versions (v1 adds signed composition offsets), so a value of 2+ indicates corruption or cursor desync in the surrounding traf.

Source

Thrown at packages/media-parser/src/containers/iso-base-media/trun.ts:30

type TRunSample = {
	sampleDuration: number | null;
	sampleSize: number | null;
	sampleFlags: number | null;
	sampleCompositionTimeOffset: number | null;
};

export const parseTrun = ({
	iterator,
	offset,
	size,
}: {
	iterator: BufferIterator;
	offset: number;
	size: number;
}): TrunBox => {
	const version = iterator.getUint8();
	if (version !== 0 && version !== 1) {
		throw new Error(`Unsupported TRUN version ${version}`);
	}

	const flags = iterator.getUint24();
	const sampleCount = iterator.getUint32();

	const dataOffset = flags & 0x01 ? iterator.getInt32() : null;
	const firstSampleFlags = flags & 0x04 ? iterator.getUint32() : null;

	const samples: TRunSample[] = [];

	for (let i = 0; i < sampleCount; i++) {
		const sampleDuration = flags & 0x100 ? iterator.getUint32() : null;
		const sampleSize = flags & 0x200 ? iterator.getUint32() : null;
		const sampleFlags = flags & 0x400 ? iterator.getUint32() : null;
		const sampleCompositionTimeOffset =
			flags & 0x800
				? version === 0
					? iterator.getUint32()

View on GitHub (pinned to 78fe4bb3fd)

Solutions

1. Validate with `mp4box -info input.mp4` or `ffprobe -v error input.mp4`.
2. Re-fetch or re-mux: `ffmpeg -i segment.m4s -c copy -f mp4 remuxed.mp4`.
3. Inspect earlier thrown errors in the same parse session — a traf-level desync is the likely cause.
4. Ensure fMP4 segments are fully downloaded before parsing.

Example fix

// before: traf desync makes trun read version 0x02
ffmpeg -i segment.m4s -c copy remuxed.mp4
// after: trun reads version 0 or 1

function isValidTrunVersion(v: number): boolean {
  return v === 0 || v === 1;
}

function isSupportedTrunVersion(v: number): v is 0 | 1 {
  return v === 0 || v === 1;
}

try {
  await parseMedia({src, fields: {dimensions: true}});
} catch (err) {
  if (err instanceof Error && err.message.startsWith('Unsupported TRUN version')) {
    // corrupt trun or upstream traf desync; re-mux or re-fetch segment
  } else throw err;
}

When it happens

Trigger: parseTrun reads a version byte other than 0 or 1 at the start of a trun box. Common when the preceding tfhd or saiz/saio box mis-sized and shifted the cursor.

Common situations: Corrupt fragmented MP4 (DASH/HLS) segments, partial segments, or files from buggy live packagers.

Related errors

• Unexpected data left in TRUN box: ${left}
• Expected stsz box in trak box
• expected 0 bytes ${bytesRemaining}
• expected 0 bytes ${bytesRemaining}
• Expected stco box in trak box

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/98c636a183da7740. Report an issue: GitHub.