Video Replace Audio API - Swap a Video's Audio Track: Pricing, Documentation

Authentication

All requests require an API key passed via header.

Pricing: Billed at $0.002 per second of OUTPUT video — and the output is as long as the SHORTER of the two inputs, so a 60-second video given a 5-second track returns 5 seconds and costs $0.01, not $0.12.

Rounding: billing is per second but always rounds up to a whole second — a 5.06-second source bills as 6 seconds. The shortest billable job is 1 second.

Retries: this is an asynchronous job on shared encoding capacity, so a request can occasionally come back processing_failed or take much longer than usual. These are transient and succeed on a retry, and a failed job is never charged — the wallet hold is released. If you chain these tools, retry a failed step rather than failing the whole pipeline.

Webhook (Optional)

Add the X-Webhook-URL header to your generate request to receive a POST callback instead of polling.

X-Webhook-URL: https://your-server.com/webhook/callback

Request Parameters - Video Replace Audio generate request

Output length is min(video, audio). The mux stops at whichever input ends first, so pairing a 60-second video with a 5-second track returns 5 seconds of picture — the remaining 55 seconds are gone, and the job still reports success. Match your durations, or trim the longer input first.

An H.264 source has its picture stream-copied, so the video is bit-identical and only the audio is rewritten. Any other codec (VP9, HEVC, AV1) is re-encoded to H.264, which takes longer and can change the file size. The result is always an MP4 with AAC audio.

Request Headers

Response Handling

Common status codes.

Error Responses

Queue system errors and model validation errors.

Queue System Errors

// 402 — Insufficient balance
{
  "error": "Insufficient Balance",
  "message": "Your wallet does not have enough balance."
}

// 400 — Model not found
{
  "error": "Model not found",
  "message": "Model 'media-mux' not found or is disabled"
}

Error via Status/Webhook

{
  "request_id": "media-mux_019dxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "status": "ERROR",
  "model_id": "media-mux",
  "error": "Description of the error",
  "output": null
}

Retrieving Results

Poll the universal status endpoint to check progress and retrieve results.

Endpoint

GET https://gateway.pixazo.ai/v2/requests/status/{request_id}
Ocp-Apim-Subscription-Key: YOUR_API_KEY

curl -H "Ocp-Apim-Subscription-Key: YOUR_API_KEY" \
  "https://gateway.pixazo.ai/v2/requests/status/media-mux_019dxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"

{
  "request_id": "media-mux_019dxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "status": "COMPLETED",
  "model_id": "media-mux",
  "error": null,
  "output": {
    "media_url": [
      "https://pub-582b7213209642b9b995c96c95a30381.r2.dev/v1/media-mux_019dxxxx/output.mp4"
    ],
    "media_type": "video/mp4"
  },
  "created_at": "2026-03-31T10:00:00.000Z",
  "updated_at": "2026-03-31T10:00:15.000Z",
  "completed_at": "2026-03-31T10:00:15.000Z"
}

Response Fields

Status Values

Status Flow

QUEUED → PROCESSING → COMPLETED
                    → FAILED
                    → ERROR

Typical Workflow

1. Send a generate request to the API endpoint
2. Save the request_id from the response
3. Poll every 5-10 seconds: GET /v2/requests/status/{request_id}
4. When status is "COMPLETED", download from output.media_url

Tip: Use X-Webhook-URL header to get a callback instead of polling.