How much does a media-probe call cost?

$0.003 per call, paid in USDC on Base via x402, with no account and no API key.

What does media-probe return?

A JSON object with 7 top-level fields: source_url, bytes, container, format_name, duration_seconds, bit_rate and streams. The example on this page is a real call over av/probe-clip.mov.

What happens when a media-probe call fails?

The tool answers with a typed JSON error from the errors table. Payment is settled only after the tool has produced its result; a call that fails inside the tool is never settled. A 503 upstream_unavailable can follow a settled call; the x402 payments guide covers it, 429, 402 and an uncertain 500.

catalogue / tools / Audio & video / Media Probe API

Media Probe API

Reads a media file's container, duration, bit rate and per-stream codec/resolution without decoding it.

Endpoint: POST /v1/media-probe
Price: $0.003 per call
Family: Audio & video
Docs: /docs/media-probe

01When to use it

Probing a media file needs the ffprobe binary AND a hardened fetch: an agent that pulls the URL itself walks past every SSRF control, and carrying an ffmpeg per call is not something an agent does inline.

When not to use it

The input is over 100 MB (104,857,600 bytes): media-probe answers too_large (413).
The destination needs more than 30 s to answer: the call ends with upstream_timeout (424).
The destination is on a private or local network: the network guard refuses it with blocked_target (403).

02Parameters

Field	Type	Required	Description
url	string	yes	Absolute http(s) URL of the audio or video file, up to 2048 characters, in a recognised container (MP4/MOV, Matroska/WebM, AVI, Ogg, WAV, FLAC, AIFF or MP3); ffprobe reads its container index and nothing is decoded.

03Limits

Limit	Value
Size cap	100 MB (104,857,600 bytes)
Timeout	30 s

04Example

The published example of media-probe, verbatim: the request body and the response it returns.

Request

POST /v1/media-probe
content-type: application/json
payment-signature: <base64 x402 payload>

{
  "url": "https://grist.tools/samples/av/probe-clip.mov"
}

Response

200 OK
payment-response: <base64 settlement receipt>

{
  "source_url": "https://grist.tools/samples/av/probe-clip.mov",
  "bytes": 33850,
  "container": "mp4",
  "format_name": "mov,mp4,m4a,3gp,3g2,mj2",
  "duration_seconds": 2,
  "bit_rate": 135400,
  "streams": [
    {
      "index": 0,
      "type": "video",
      "codec": "png",
      "codec_long_name": "PNG (Portable Network Graphics) image",
      "width": 64,
      "height": 36,
      "frame_rate": 2,
      "sample_rate": null,
      "channels": null
    },
    {
      "index": 1,
      "type": "audio",
      "codec": "pcm_s16le",
      "codec_long_name": "PCM signed 16-bit little-endian",
      "width": null,
      "height": null,
      "frame_rate": null,
      "sample_rate": 8000,
      "channels": 1
    }
  ]
}

Sample file: av/probe-clip.mov. Two-second QuickTime clip: 64x36 PNG video at 2 fps with a light square moving across a slate field, plus the three rising 500 Hz beeps of waveform-beeps.wav as mono 16-bit PCM at 8 kHz.

In the sample itself, the ftyp box names major brand qt, minor version 512 and compatible brands qt; the top-level boxes run ftyp, wide, mdat and moov, so the moov index comes after the media data; mvhd counts 2,000 ticks at 1,000 per second, 2 s; the 2 tracks are url with sample entry png and url with sample entry sowt.

Response field	Type	In the example
source_url	string	"https://grist.tools/samples/av/probe-clip.mov"
bytes	number	33850
container	string	"mp4"
format_name	string	"mov,mp4,m4a,3gp,3g2,mj2"
duration_seconds	number	2
bit_rate	number	135400
streams	array	2 items, each with index, type, codec, codec_long_name, width, height, frame_rate, sample_rate and channels

05Call it from code

JavaScript

// media-probe: $0.003 per call, paid in USD Coin on eip155:8453 via x402
// Install: npm install @x402/fetch@2 @x402/evm@2 viem@2
// Save as client.mjs (ES module, Node 18+), export EVM_PRIVATE_KEY with the paying wallet's key in your shell, then run: node client.mjs
// The wrapper reads the 402 (payment-required), signs and retries with payment-signature.
import { wrapFetchWithPayment, x402Client, decodePaymentResponseHeader } from '@x402/fetch'
import { ExactEvmScheme } from '@x402/evm/exact/client'
import { privateKeyToAccount } from 'viem/accounts'

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY)
const client = new x402Client().register('eip155:8453', new ExactEvmScheme(account))
const fetchWithPayment = wrapFetchWithPayment(fetch, client)

const body = {
  "url": "https://grist.tools/samples/av/probe-clip.mov"
}

const res = await fetchWithPayment('https://grist.tools/v1/media-probe', {
  method: 'POST',
  headers: { 'content-type': 'application/json' },
  body: JSON.stringify(body),
})
console.log(res.status, await res.json())
const settle = res.headers.get('payment-response')
if (settle) console.log(decodePaymentResponseHeader(settle).transaction)

Python

# media-probe: $0.003 per call, paid in USD Coin on eip155:8453 via x402
# Install: pip install "x402[requests,evm]>=2.24,<3"
# The session reads the 402 (payment-required), signs and retries with payment-signature.
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http import decode_payment_response_header
from x402.http.clients.requests import x402_requests
from x402.mechanisms.evm.exact import register_exact_evm_client
from x402.mechanisms.evm.signers import EthAccountSigner

account = Account.from_key(os.environ["EVM_PRIVATE_KEY"])
client = x402ClientSync()
register_exact_evm_client(client, EthAccountSigner(account), networks="eip155:8453")
session = x402_requests(client)

payload = {
    "url": "https://grist.tools/samples/av/probe-clip.mov"
}

res = session.post("https://grist.tools/v1/media-probe", json=payload)
print(res.status_code, res.json())
settle = res.headers.get("payment-response")
if settle:
    print(decode_payment_response_header(settle).transaction)

curl

# media-probe: $0.003 per call, paid in USD Coin on eip155:8453 via x402
# 1. Unpaid call: HTTP 402, the requirements in the payment-required header (base64 JSON) and in the body.
curl -i -X POST 'https://grist.tools/v1/media-probe' -H 'content-type: application/json' -d '{"url":"https://grist.tools/samples/av/probe-clip.mov"}'

# 2. Same call with the signed payment (an EIP-3009 authorization, EIP-712 signed: it cannot be
#    typed by hand). x-payment is accepted as the v1 alternative. HTTP 200 carries payment-response.
curl -i -X POST 'https://grist.tools/v1/media-probe' -H 'content-type: application/json' -H 'payment-signature: <base64 x402 payload>' -d '{"url":"https://grist.tools/samples/av/probe-clip.mov"}'

06Errors

Code	HTTP	For this service
invalid_input	400	The body does not match the schema; its fields are url.
blocked_target	403
unreachable_target	424
upstream_timeout	424
unsupported_content_type	415
too_large	413
unprocessable	422
internal	500

Input that is rejected before the tool runs (malformed JSON, schema mismatch, body over the size limit) is never charged.

When each code is raised, and what it means for payment: /docs/media-probe.

07Questions

How much does a media-probe call cost?: $0.003 per call, paid in USDC on Base via x402, with no account and no API key.
What does media-probe return?: A JSON object with 7 top-level fields: source_url, bytes, container, format_name, duration_seconds, bit_rate and streams. The example on this page is a real call over av/probe-clip.mov.
What happens when a media-probe call fails?: The tool answers with a typed JSON error from the errors table. Payment is settled only after the tool has produced its result; a call that fails inside the tool is never settled. A 503 upstream_unavailable can follow a settled call; the x402 payments guide covers it, 429, 402 and an uncertain 500.

08Related

Audio & video guide