Lufs Math

{
  "asOf": "2026-10-11T14:38:34.877Z",
  "ceilingDbtp": -1,
  "combinedLufs": null,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "gainDb": -4.5,
  "gainLinear": 0.595662,
  "limitingNeeded": false,
  "loudestSegmentLufs": null,
  "measuredLufs": -9.5,
  "mode": "gain",
  "newTruePeakDbtp": -4.8,
  "notChecked": [
    "BS.1770 gating (absolute -70 LUFS and relative -10 LU): combining segments here averages ALL energy ungated, so measure a whole programme with a meter for a delivery value",
    "loudness range and short-term or momentary limits (for example the EBU R128 +-0.5 LU tolerance)",
    "…2 more"
  ],
  "peakHeadroomDb": 3.8,
  "platform": "spotify",
  "platformTargets": {
    "amazon-music": -14,
    "apple-music": -16,
    "arib-tr-b32": -24,
    "atsc-a85": -24,
    "ebu-r128": -23,
    "podcast": -16,
    "spotify": -14,
    "tidal": -14,
    "youtube": -14
  },
  "quietestSegmentLufs": null,
  "reasons": [
    "Loudness changes dB for dB with gain, so the gain is simply target minus measured.",
    "Turning down never raises the peak."
  ],
  "segmentCount": null,
  "source": "ITU-R BS.1770 / EBU R128 loudness arithmetic (level offsets add in dB; energies average linearly); platform targets as commonly published, computed locally",
  "summary": "-9.5 LUFS to -14 LUFS (spotify): -4.5 dB. True peak -0.3 becomes -4.8 dBTP, 3.8 dB under the -1 dBTP ceiling.",
  "targetLufs": -14,
  "totalSeconds": null,
  "verdict": "TURN_DOWN"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://audio-calc.x402tookit.com/lufs-math?ceilingDbtp=-1&lufs=-9.5&target=spotify&truePeakDbtp=-0.3'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://audio-calc.x402tookit.com/lufs-math?ceilingDbtp=-1&lufs=-9.5&target=spotify&truePeakDbtp=-0.3' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Faudio-calc.x402tookit.com%2Flufs-math
const res = await pay("https://audio-calc.x402tookit.com/lufs-math?ceilingDbtp=-1&lufs=-9.5&target=spotify&truePeakDbtp=-0.3");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://audio-calc.x402tookit.com/lufs-math?ceilingDbtp=-1&lufs=-9.5&target=spotify&truePeakDbtp=-0.3")
    print(res.status_code, res.text)