Free LUFS Loudness & Media Info API

POST https://audo.ai/api/try/media-info (tool analyze_audio) is a free cloud REST API that measures EBU R 128 integrated loudness (LUFS), true peak (dBTP), loudness range (LU), RMS noise floor (dB), sample peak, average RMS level, clipped samples, silent timestamp ranges, and container/codec details for any audio or video file up to 10 GB.

Cost: Always free ($0.00, 0 credits) for the entire file—up to 20 files a day per person without an API key or account.
Formats: Audio (WAV, MP3, M4A, AAC, FLAC, OGG, Opus, WebM, AIFF) and video (MP4, MOV, MKV, WebM, AVI).
Web tool: Try it in the browser on the Free LUFS meter or File info.

Measure LUFS loudness with curl

Send a local audio or video file as multipart/form-data, or pass a public HTTPS URL as JSON:

Terminal

# Upload a local file:
curl -F file=@episode.wav https://audo.ai/api/try/media-info -D response.headers -o response.body

# Or inspect a public HTTPS URL:
curl -X POST https://audo.ai/api/try/media-info \
  -H "Content-Type: application/json" \
  -d '{"url": "https://example.com/episode.mp3", "detail": "concise"}'

For files up to an hour long, /api/try/media-info typically finishes within a few seconds and returns 200 OK with the JSON report directly.

Example JSON response

JSON

{
  "duration_seconds": 184.2,
  "format_name": "mp3",
  "size_bytes": 4421880,
  "has_audio": true,
  "has_video": false,
  "audio": {
    "codec": "mp3",
    "sample_rate": 48000,
    "channels": 2,
    "bit_rate": 192000
  },
  "video": null,
  "loudness": {
    "integrated_lufs": -18.4,
    "true_peak_dbtp": -2.1,
    "lra_lu": 6.3
  },
  "noise_floor_db": -64.2,
  "peak_db": -2.2,
  "rms_db": -21.5,
  "clipped_samples": 0,
  "silences": [
    { "start_seconds": 12.45, "end_seconds": 15.12 },
    { "start_seconds": 48.3, "end_seconds": 51.05 }
  ]
}

Response fields

Field	Type	Description
`loudness.integrated_lufs`	`number`	Gated EBU R 128 / ITU-R BS.1770 integrated loudness across the whole file, in LUFS (equal to LKFS).
`loudness.true_peak_dbtp`	`number`	Highest inter-sample reconstructed peak, in dBTP. Keep at or below `-1.0 dBTP` for podcasts and streaming.
`loudness.lra_lu`	`number`	Loudness range (LRA) in LU, measuring the spread between quiet and loud sections.
`noise_floor_db`	`number`	RMS level of the quietest steady room-tone windows, in dB (useful for ACX audiobook `-60 dB` checks).
`peak_db`	`number`	Sample peak level in dBFS.
`rms_db`	`number`	Overall RMS level in dBFS (ACX audiobooks require `-23` to `-18 dB` RMS).
`clipped_samples`	`number`	Number of digital samples hitting full scale. `0` means no digital clipping.
`silences`	`array`	Silent stretches of `0.7` seconds or longer as `{"start_seconds", "end_seconds"}` pairs. `detail="concise"` (default) returns up to 50; `detail="full"` returns all of them.
`duration_seconds`	`number`	Verified decoded duration in seconds.
`audio` / `video`	`object \	null`	Codec, sample rate, channel count, bitrate, pixel dimensions, and frame rate.

Normalize to `-16 LUFS` or `-14 LUFS` in a second call

Once you have measured a file, you can normalize it to platform loudness targets with POST https://audo.ai/api/try/loudness (tool adjust_loudness, web page Boost volume). The first hour of each file is free (10 times a day, no API key), and whole files with an API key cost $0.01/min ($0.60/hr):

`target` value	Target loudness	True-peak ceiling	Best for
`podcast` (default)	`-16 LUFS`	`-1 dBTP`	Apple Podcasts and RSS podcast feeds
`streaming`	`-14 LUFS`	`-1 dBTP`	Spotify, YouTube, and web video
`broadcast`	`-23 LUFS`	`-1 dBTP`	EBU R 128 broadcast television and radio
`audiobook`	`-23` to `-18 dB RMS`	`-3 dB` peak	Audible / ACX audiobook submissions (also returns `acx.passes` and `acx.problems`)
`custom`	`custom_lufs` (`-30` to `-5`)	`-1 dBTP`	Any custom LUFS target