remotion-dev/remotion · error

Could not find audio segment

Error message

Could not find audio segment

What it means

Thrown by getNumberOfChannels() in the WebM/Matroska traversal layer when the supplied TrackEntry has no child segment of type 'Audio'. Unlike getSampleRate() and getBitDepth() (which return null in this case), getNumberOfChannels treats a missing Audio segment as a hard error because a channel count is meaningless for a non-audio track. The throw signals that the caller passed the wrong track kind or inspected the track before its Audio child was parsed.

Source

Thrown at packages/media-parser/src/containers/webm/traversal.ts:322

	if (!audioSegment) {
		return null;
	}

	const samplingFrequency = audioSegment.value.find(
		(b) => b.type === 'SamplingFrequency',
	);

	if (!samplingFrequency || samplingFrequency.type !== 'SamplingFrequency') {
		return null;
	}

	return samplingFrequency.value.value;
};

export const getNumberOfChannels = (track: TrackEntry): number => {
	const audioSegment = getAudioSegment(track);
	if (!audioSegment) {
		throw new Error('Could not find audio segment');
	}

	const channels = audioSegment.value.find((b) => b.type === 'Channels');

	if (!channels || channels.type !== 'Channels') {
		return 1;
	}

	return channels.value.value;
};

export const getBitDepth = (track: TrackEntry): number | null => {
	const audioSegment = getAudioSegment(track);
	if (!audioSegment) {
		return null;
	}

	const bitDepth = audioSegment.value.find((b) => b.type === 'BitDepth');

View on GitHub (pinned to 78fe4bb3fd)

Solutions

1. Filter tracks to audio tracks before calling getNumberOfChannels: use getAudioSegment(track) (which returns null instead of throwing) to gate the call.
2. If parsing lazily, wait until parseMedia has emitted the tracks and the Audio child is populated before reading channel count.
3. Validate the file with a tool such as ffprobe; a missing Audio element usually indicates a corrupt or non-audio track.
4. Fall back to a default of 1 channel when getAudioSegment(track) returns null rather than calling getNumberOfChannels unconditionally.

Example fix

// before
for (const track of tracks) {
  const channels = getNumberOfChannels(track);
}

// after
for (const track of tracks) {
  if (!getAudioSegment(track)) continue;
  const channels = getNumberOfChannels(track);
}

import {getAudioSegment} from '@remotion/media-parser/containers/webm/traversal';

const audio = getAudioSegment(track);
if (audio) {
  const channels = getNumberOfChannels(track);
}

const isAudioTrackEntry = (track: TrackEntry): boolean =>
  track.value.some((b) => b.type === 'Audio');

try { const ch = getNumberOfChannels(track); } catch (e) { if (e.message === 'Could not find audio segment') { /* skip non-audio track */ } else throw e; }

When it happens

Trigger: Calling getNumberOfChannels(track) on a TrackEntry that is a video track, a subtitle track, or an audio track whose 'Audio' child segment has not yet been encountered by the parser. Also triggered by passing a TrackEntry obtained from a malformed WebM/MKV that omits the Audio element.

Common situations: Iterating over all Matroska tracks and calling getNumberOfChannels on every entry without first filtering for audio tracks. Reading channel count during early parsing before the audio segment is available. Feeding a truncated or non-standard MKV/WebM produced by a buggy muxer.

Related errors

• Expected vorbis private data version 2
• Error parsing vorbis codec private
• Could not find sample rate or number of channels
• No 'src' was passed to <Html5Audio>.
• No src passed

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/cf93eab63bf1a193. Report an issue: GitHub.