remotion-dev/remotion · error · Error

Expected vorbis private data version 2

Error message

Expected vorbis private data version 2

What it means

For a Vorbis track the Matroska CodecPrivate starts with a Xiph-lacing header whose first byte is packet-count-minus-1. Vorbis uses exactly 3 header packets (identification, comment, setup), so that count byte must be 2. getAudioDescription rejects any other value because the lacing model assumes three packets.

Source

Thrown at packages/media-parser/src/containers/webm/description.ts:21

import {getCodecSegment, getPrivateData} from './traversal';

export const getAudioDescription = (
	track: TrackEntry,
): undefined | Uint8Array => {
	const codec = getCodecSegment(track);
	if (!codec || codec.value !== 'A_VORBIS') {
		return undefined;
	}

	// how to parse vorbis private
	// https://github.com/google/ExoPlayer/blob/dd430f7053a1a3958deea3ead6a0565150c06bfc/library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractor.java#L2466
	const privateData = getPrivateData(track);
	if (!privateData) {
		return undefined;
	}

	if (privateData[0] !== 2) {
		throw new Error('Expected vorbis private data version 2');
	}

	let offset = 1;
	let vorbisInfoLength = 0;
	let vorbisSkipLength = 0;

	while ((privateData[offset] & 0xff) === 0xff) {
		vorbisInfoLength += 0xff;
		offset++;
	}

	vorbisInfoLength += privateData[offset++] & 0xff;

	while ((privateData[offset] & 0xff) === 0xff) {
		vorbisSkipLength += 0xff;
		offset++;
	}

View on GitHub (pinned to 78fe4bb3fd)

Solutions

1. Re-encode the audio: ffmpeg -i in.webm -c:a libvorbis out.webm.
2. Verify the Vorbis headers with ffprobe.
3. Use Mediabunny; try/catch parseMedia().

Example fix

# re-encode Vorbis audio cleanly
ffmpeg -i in.webm -c:v copy -c:a libvorbis out.webm

await parseMedia({ src: 'out.webm' });

// ffprobe confirms Vorbis headers are intact
// ffprobe -v error -show_streams in.webm

try {
  await parseMedia({ src: 'in.webm' });
} catch (err) {
  if (err instanceof Error && /vorbis private data version 2/i.test(err.message)) {
    // re-encode Vorbis or skip
  } else throw err;
}

When it happens

Trigger: A Vorbis track whose CodecPrivate[0] !== 2: wrong packet count, corrupted lacing byte, truncated CodecPrivate, or a non-Vorbis stream tagged A_VORBIS.

Common situations: Broken muxer output; truncated/corrupted CodecPrivate; legacy or non-standard Vorbis packaging.

Related errors

• Error parsing vorbis codec private
• Expected av1 private data to be version 1
• Expected av1 private data to be version 1, got ${version}
• Unexpected sampling frequency index ${samplingFrequencyIndex
• Could not find number of channels

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/4dad144eba175d7d. Report an issue: GitHub.