# grist.tools Audio Extract

> grist.tools Audio Extract is a paid API for AI agents from grist.tools, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-02).

Extracts and converts audio from a remote video or audio file URL into a chosen audio format (MP3, WAV, FLAC, AAC, or Opus)

## Facts

- Endpoint: POST https://grist.tools/v1/audio-extract?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/grist-tools-audio-extract-5d6e2631
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_8RZ7ecv9G-dObpsB0NBeJ

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 grist-tools-audio-extract-5d6e2631 -d '<json body>'
```

Example prompt: Can you extract the audio from this MP4 video — https://example.com/lecture.mp4 — and give it to me as a WAV file?

## When to prefer this

Choose this endpoint when you need a simple, pay-per-call audio extraction or format conversion from a publicly accessible video or audio URL, without managing your own FFmpeg infrastructure. It is ideal for one-off conversions at $0.003/call with no subscription. It supports a wide range of input containers and five common output formats, and it handles multi-track files via stream selection.

## Known failure modes

- URL is not reachable or returns a non-200 response
- File format is not a recognised container (must be MP4/MOV, MKV/WebM, AVI, Ogg, WAV, FLAC, AIFF, or MP3)
- Audio stream duration exceeds 3600 seconds
- Requested stream index does not exist in the file (returns unprocessable error)
- Stream index out of allowed range (0–63)
- URL exceeds 2048 characters
- Payment verification fails before processing begins

## How this service works

One endpoint does one thing, always the same way, for a fraction of a cent. Payment is verified before the handler runs and settled only after it succeeds, so a rejected or failed call is never a charged call.

## Output

Returns the converted audio file in the requested format (defaulting to MP3). The file contains the extracted audio stream from the source video or audio container, transcoded using the appropriate codec (LAME for MP3, 16-bit PCM for WAV, FLAC, ADTS stream for AAC, or Ogg-wrapped Opus). Payment is only charged on success.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "url"
 ],
 "properties": {
  "to": {
   "enum": [
    "wav",
    "mp3",
    "flac",
    "aac",
    "opus"
   ],
   "type": "string",
   "description": "Output format for the extracted track: wav (16-bit PCM), mp3 (LAME), flac, aac (ADTS stream) or opus (in an Ogg container); defaults to mp3."
  },
  "url": {
   "type": "string",
   "description": "Absolute http(s) URL of a video or audio file, up to 2048 characters, in a recognised container (MP4/MOV, Matroska/WebM, AVI, Ogg, WAV, FLAC, AIFF or MP3); the selected audio stream must last at most 3600 seconds."
  },
  "stream": {
   "type": "integer",
   "description": "Zero-based index among the audio streams only (0 is the first audio track), 0 to 63; an index the file does not have is refused as unprocessable."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/grist-tools-audio-extract-5d6e2631/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from grist.tools](https://www.zero.xyz/host/grist.tools/llms.txt)