What causes "Unsupported bits per sample: ${bitsPerSample}" in remotion-dev/remotion?

Inspect bitsPerSample via ffprobe or soxi.

remotion-dev/remotion · error · Error

Unsupported bits per sample: ${bitsPerSample}

Error message

Unsupported bits per sample: ${bitsPerSample}

What it means

After accepting the format tag, parseFmt maps bitsPerSample to a codec string: 16 -> pcm-s16, 32 -> pcm-s32, 24 -> pcm-s24. Any other bit depth has no mapping and is rejected because the WebCodecs decode path only covers those three. The thrown value is the raw bitsPerSample.

Source

Thrown at packages/media-parser/src/containers/wav/parse-fmt.ts:76

		);
	}

	const numberOfChannels = iterator.getUint16Le();
	const sampleRate = iterator.getUint32Le();
	const byteRate = iterator.getUint32Le();
	const blockAlign = iterator.getUint16Le();
	const bitsPerSample = iterator.getUint16Le();

	const format =
		bitsPerSample === 16
			? 'pcm-s16'
			: bitsPerSample === 32
				? 'pcm-s32'
				: bitsPerSample === 24
					? 'pcm-s24'
					: null;
	if (format === null) {
		throw new Error(`Unsupported bits per sample: ${bitsPerSample}`);
	}

	const wavHeader: WavFmt = {
		bitsPerSample,
		blockAlign,
		byteRate,
		numberOfChannels,
		sampleRate,
		type: 'wav-fmt',
	};

	state.structure.getWavStructure().boxes.push(wavHeader);

	if (audioFormat === 65534) {
		const extraSize = iterator.getUint16Le();
		if (extraSize !== 22) {
			throw new Error(
				`Only supporting WAVE with 22 extra bytes, but got ${extraSize} bytes extra size`,

View on GitHub (pinned to 78fe4bb3fd)

Solutions

Inspect bitsPerSample via ffprobe or soxi.
Convert to a supported depth: ffmpeg -i in.wav -c:a pcm_s16le out.wav (or pcm_s24le / pcm_s32le).
For 8-bit sources, upscale to 16-bit with ffmpeg.
Use Mediabunny; fall back in try/catch otherwise.

Example fix

# 8-bit WAV -> 16-bit PCM
ffmpeg -i in.wav -c:a pcm_s16le out.wav

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

Defensive patterns

Strategy: try-catch

Validate before calling

// check bit depth first
// ffprobe -show_entries stream=bits_per_sample -of default=nw=1 in.wav
// must be 16, 24, or 32

Type guard

const SUPPORTED_BITS = new Set([16, 24, 32]);
const isSupportedBitDepth = (bits: number) => SUPPORTED_BITS.has(bits);

Try / catch

try {
  await parseMedia({ src: 'in.wav' });
} catch (err) {
  if (err instanceof Error && /bits per sample/i.test(err.message)) {
    // unsupported depth — convert with ffmpeg or skip
  } else throw err;
}

Prevention

Normalize bit depth to 16/24/32 when generating assets.
Probe bits_per_sample before parsing.
Fall back to Mediabunny for unusual depths.

When it happens

Trigger: A PCM WAV whose bitsPerSample is not 16/24/32: most often 8-bit PCM, 32-bit float mislabeled with wFormatTag 1, or unusual 12/20/48-bit depths.

Common situations: 8-bit WAVs from old games/samplers; 32-bit float files saved without the EXTENSIBLE wrapper; niche high-res audio.

Related errors

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/900c9d9f1468e820. Report an issue: GitHub.