Pitch Speed

{
  "asOf": "2026-10-12T01:46:28.869Z",
  "bpmAfter": 127.1356,
  "cents": 100,
  "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.",
  "hzAfter": 466.1638,
  "inputMode": "semitones",
  "isSpeedUp": true,
  "notChecked": [
    "time-stretch and pitch-shift algorithms, which change pitch without speed and add artefacts",
    "the useful range of your sampler, turntable or plugin",
    "…1 more"
  ],
  "octaves": 0.083333,
  "ratio": 1.05946309,
  "reasons": [
    "Varispeed changes pitch and tempo together by the same ratio: one semitone is a factor of 2^(1/12), about 5.946 percent.",
    "Cents = 1200 x log2(ratio), so 1200 cents is one octave (ratio 2)."
  ],
  "semitones": 1,
  "source": "computed locally (ratio r = 2^(semitones / 12); cents = 1200 x log2 r; speed percent = (r - 1) x 100)",
  "speedPercent": 5.94631,
  "summary": "Ratio 1.059463 = 1 semitone(s) = 100 cents = 5.946% speed; 120 BPM becomes 127.14.",
  "verdict": "COMPUTED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://music-production-calc.x402tookit.com/pitch-speed?bpm=120&hz=440&semitones=1'

# 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://music-production-calc.x402tookit.com/pitch-speed?bpm=120&hz=440&semitones=1' \
  | 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%2Fmusic-production-calc.x402tookit.com%2Fpitch-speed
const res = await pay("https://music-production-calc.x402tookit.com/pitch-speed?bpm=120&hz=440&semitones=1");
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://music-production-calc.x402tookit.com/pitch-speed?bpm=120&hz=440&semitones=1")
    print(res.status_code, res.text)