# Relaystation Audio Mix

> Relaystation Audio Mix is a paid API for AI agents from api.relaystation.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Mixes multiple audio tracks into a single output using amix, with optional loudness normalization — ideal for combining voiceover and background music in one API call

## Facts

- Endpoint: POST https://api.relaystation.ai/v1/media/audio-mix
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/relaystation-audio-mix-55d01fab
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fZv9KUTIYUHh1_riZskRw

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 relaystation-audio-mix-55d01fab -d '<json body>'
```

Example prompt: Mix my voiceover recording and background music track into a single audio file, and apply loudness normalization so they balance well together.

## When to prefer this

Choose this endpoint when you need to combine multiple audio tracks (e.g. voiceover plus music) into a single output file programmatically, especially within an automated agent workflow where per-MB pricing and optional loudness normalization are desirable. Ideal for content pipelines, podcast production, video post-production, and any use case requiring serverless audio mixing without managing FFmpeg infrastructure.

## Known failure modes

- Unsupported audio format returns an error
- Missing or malformed audio track input causes a 400 bad request
- Exceeding size or track count limits may result in rejection
- Insufficient USDC balance to cover the call results in payment failure
- Network timeout on large audio files

## How this service works

$0.0005/MB. Mix multiple audio tracks down to one (amix), optional loudness normalize — voiceover + music in one call. 1¢ x402 min; remainder auto-credits — relaystation.ai/penny

## Output

A single mixed-down audio file combining all input tracks, optionally loudness-normalized. Pricing is $0.0005/MB of input data with a 1¢ minimum; any remainder is auto-credited to the account.

## Request schema (JSON Schema)

```json
{
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "type": "object",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "type": "string",
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ]
    },
    "bodyType": {
     "type": "string",
     "enum": [
      "json",
      "form-data",
      "text"
     ]
    },
    "body": {
     "type": "object",
     "properties": {
      "file": {
       "type": "object",
       "description": "cputools input-source: { inline: <base64 ≤ 4 MiB> } or { inputKey: <scratch key ≤ 50 MB> }. The input container must sniff (ffprobe) to the live allowlist (operator-tunable cputools.media.input_formats): 3g2, 3gp, aac, asf, avi, flac, flv, gif, m4a, m4v, matroska, mj2, mov, mov,mp4,m4a,3gp,3g2,mj2, mp3, mp4, mpeg, mpegts, mpegvideo, ogg, wav, webm, wmv. An off-list input is a free 422 UNSUPPORTED_FORMAT."
      },
      "inputs": {
       "type": "array",
       "minItems": 1,
       "maxItems": 8,
       "items": {
        "type": "object",
        "description": "cputools input-source: { inline: <base64 ≤ 4 MiB> } or { inputKey: <scratch key from /v1/cputools/upload-url, ≤ 50 MB> }."
       }
      },
      "format": {
       "type": "string",
       "enum": [
        "mp3",
        "m4a",
        "aac",
        "wav",
        "ogg",
        "flac"
       ]
      },
      "normalize": {
       "type": "boolean"
      }
     }
    }
   },
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   },
   "required": [
    "type"
   ]
  }
 },
 "required": [
  "input"
 ]
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/relaystation-audio-mix-55d01fab/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.relaystation.ai](https://www.zero.xyz/host/api.relaystation.ai/llms.txt)