# RTK Motion MoCap BVH Data Endpoint

> RTK Motion MoCap BVH Data Endpoint is a paid API for AI agents from api.rtkmotion.io, paid per call via x402, $0.25/call, status unknown (last checked 2026-09-15).

Returns a signed BVH motion capture data excerpt (with optional full 300-frame hierarchy) from RTK Motion's 4D capture system, including a signed download URL and provenance signature.

## Facts

- Endpoint: GET https://api.rtkmotion.io/paid/mocap
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/rtk-motion-mocap-bvh-data-endpoint-e729b053
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Or_vruebAy1Z0oV6tjF5W

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 rtk-motion-mocap-bvh-data-endpoint-e729b053
```

Example prompt: Can you grab me a full BVH motion capture sample from RTK Motion — I need the complete 300-frame hierarchy with the signed download URL and provenance info.

## When to prefer this

Use this endpoint when you need authenticated, cryptographically signed BVH motion capture data with provenance for 4D motion capture workflows, animation pipelines, or biomechanics analysis. Prefer this over generic mocap APIs when verifiable on-chain provenance (secp256k1 signature) and 120fps fidelity matter.

## Known failure modes

- Invalid or missing 'detail' query param value (not 'basic' or 'full') may return default basic excerpt
- Payment failure (x402) if USDC payment of $0.25 is not completed before request
- Signed URL expiry if the token in the response URL is not used promptly
- Network timeout if the 4D capture backend is unavailable
- Unauthorized if x402 payment header is malformed or missing

## How this service works

RTK Motion — 4D motion capture biomechanics. Two-subject grappling capture, 5 s (300 frames @ 60 fps, 56 joints each), delivered as DERIVED ANALYSIS inline: inter-subject engagement distance and contact time — which single-actor corpora cannot produce — plus per-joint excursion, bilateral asymmetry, motion energy, and 56-joint→43-DOF retarget fidelity. Signed raw-BVH URLs included. Full 20 s captures, NPZ trajectories and bundles via /mcp.

## Output

Returns a JSON object containing: BVH format excerpt (basic compact sample or full 300-frame hierarchy), FPS (120), joint count (24), duration in seconds (5), a signed URL for full data download, and a secp256k1-ECDSA provenance signature from the RTK Motion signing address.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "detail": {
       "type": "string",
       "description": "Level of BVH excerpt detail: 'basic' (compact sample, default) or 'full' (complete 300-frame hierarchy)."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "fps": 60,
  "domain": "4D Motion Capture",
  "format": "BVH",
  "joints": 56,
  "subjects": {
   "subject_1": {
    "bytes": 148213,
    "r2_key": "…",
    "sha256": "…",
    "download_url": "https://api.rtkmotion.io/data/...?token=...&expires=..."
   }
  },
  "next_step": {
   "note": "download_url gives the raw BVH behind the analysis; it expires, the analysis does not.",
   "action": "None — the analysis is delivered in full inline",
   "required": false,
   "expires_in_seconds": 900
  },
  "provenance": {
   "algorithm": "secp256k1-ECDSA",
   "signed_by": "0x6C11F8a21f7ca922F483Ed21C3b6c2d9B305B10C"
  },
  "duration_seconds": 5,
  "bvh_excerpt_provenance": "HIERARCHY\nROOT Hips\n{..."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/rtk-motion-mocap-bvh-data-endpoint-e729b053/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.rtkmotion.io](https://www.zero.xyz/host/api.rtkmotion.io/llms.txt)