# Audio Loudness Normalization (EBU R128 / LUFS)

> Audio Loudness Normalization (EBU R128 / LUFS) is a paid API for AI agents from agent402.tools, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-15).

Loudness-normalizes an audio or video file from a public URL to a target LUFS using ffmpeg's loudnorm filter (EBU R128) and returns an MP3

## Facts

- Endpoint: POST https://agent402.tools/api/audio-normalize
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/audio-loudness-normalization-ebu-r128-lufs-39dc95e4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_sQotj4kpJm_Gc1qDfCjbM

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability audio-loudness-normalization-ebu-r128-lufs-39dc95e4 -d '<json body>'
```

Example prompt: Can you loudness-normalize this audio file to -16 LUFS so it meets podcast standards? The file is at https://example.com/episode.wav

## When to prefer this

Use this endpoint when you need to normalize audio or video loudness to a specific LUFS target (e.g. -16 for podcasts, -14 for YouTube, -23 for broadcast) using the industry-standard EBU R128 algorithm. Ideal for podcast production pipelines, TTS output leveling, and clip normalization where consistent perceived loudness is required. Accepts any public URL and returns MP3, making it convenient for serverless or agent-driven workflows.

## Known failure modes

- URL is not publicly accessible or returns 4xx/5xx — file cannot be fetched
- File exceeds 30MB size limit — request rejected
- targetLufs value outside supported range of -36 to -8 — validation error
- Unsupported audio/video format that ffmpeg cannot decode
- Network timeout fetching source media file
- Payment not received or invalid x402 payment header

## How this service works

Loudness-normalize any audio/video URL to a target LUFS with ffmpeg's loudnorm (EBU R128) and return MP3 - consistent levels for podcasts, clips, and TTS output. Body: {"url":"https://…/audio.wav","targetLufs":-16?}.

## Output

Returns an MP3 audio file that has been loudness-normalized to the requested LUFS target using ffmpeg's EBU R128 loudnorm filter, suitable for podcasts, streaming platforms, or TTS output.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Public URL of the media file (max 30MB)"
  },
  "targetLufs": {
   "type": "number",
   "description": "Integrated loudness target, -36 to -8 (default -16)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "bytes": 2210000,
  "format": "mp3",
  "mp3Base64": "SUQzBAAAAA…",
  "targetLufs": -16,
  "truePeakDb": -1.5
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/audio-loudness-normalization-ebu-r128-lufs-39dc95e4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)