What causes "Expected MPEG Version 1 or 2" in remotion-dev/remotion?

Verify the file is a valid MP3 using `ffprobe`.

remotion-dev/remotion · error · Error

Expected MPEG Version 1 or 2

Error message

Expected MPEG Version 1 or 2

What it means

Thrown by `innerParseMp3PacketHeader` when the 2-bit audio version ID field equals `0b01`, which is marked 'reserved' in the MPEG specification. The parser accepts `0b00` (MPEG 2.5), `0b10` (MPEG 2), and `0b11` (MPEG 1), but not the reserved `0b01`.

Source

Thrown at packages/media-parser/src/containers/mp3/parse-packet-header.ts:193

		const expectToBe1 = iterator.getBits(1);
		if (expectToBe1 !== 1) {
			throw new Error('Expected 1');
		}
	}

	const audioVersionId = iterator.getBits(2);
	/**
   * 00 - MPEG Version 2.5 (later extension of MPEG 2)
     01 - reserved
     10 - MPEG Version 2 (ISO/IEC 13818-3)
     11 - MPEG Version 1 (ISO/IEC 11172-3)
   */
	if (
		audioVersionId !== 0b11 &&
		audioVersionId !== 0b10 &&
		audioVersionId !== 0b00
	) {
		throw new Error('Expected MPEG Version 1 or 2');
	}

	const mpegVersion = audioVersionId === 0b11 ? 1 : (2 as MpegVersion);

	const layerBits = iterator.getBits(2);
	/**
   * 00 - reserved
     01 - Layer III
     10 - Layer II
     11 - Layer I
   */
	if (layerBits === 0b00) {
		throw new Error('Expected Layer I, II or III');
	}

	const layer = layerBits === 0b11 ? 1 : layerBits === 0b10 ? 2 : 3;

	iterator.getBits(1); // 0b1 means that there is no CRC, 0b0 means there is. Not validating checksum though

View on GitHub (pinned to 78fe4bb3fd)

Solutions

Verify the file is a valid MP3 using `ffprobe`.
Re-download or re-encode the file from a known-good source.
Check for file corruption due to incomplete transfers.
Report the file at remotion.dev/report if it appears to be a standard MP3.

Example fix

# verify file
ffprobe -v error -i input.mp3

# re-encode
ffmpeg -i input.mp3 -codec:a libmp3lame output.mp3

Defensive patterns

Strategy: try-catch

Try / catch

try {
  await parseMedia({src, fields: {durationInSeconds: true}});
} catch (e) {
  if (e instanceof Error && e.message === 'Expected MPEG Version 1 or 2') {
    console.error('The MP3 frame header contains a reserved MPEG version ID.');
  }
  throw e;
}

Prevention

Validate MP3 files with ffprobe before parsing.
Re-encode corrupt files with ffmpeg/LAME.
Check for partial downloads or storage corruption.
Use try-catch for untrusted user-uploaded audio files.

When it happens

Trigger: During frame header parsing (`parse-packet-header.ts:188-194`), `audioVersionId` read from the 2 bits after the sync word is `0b01`. No valid MPEG audio version maps to this value.

Common situations: Corrupt frame headers where the version bits are flipped. Non-MP3 data being parsed as MPEG audio. Files with byte-level corruption from bad transfers or disk errors. Misidentified file formats.

Related errors

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/cf3e5b269b03c037. Report an issue: GitHub.