Head Swap – Analyze

namifusion/head-swap/analyze

Detect and track heads in a video with SAM3. Returns a head list with preview images and a track manifest for the generate step.

Examples

Head Swap – Analyze Examples 1

Parameters

NameTypeDefaultConstraintsDescription
resolutionResolutionselect720p480p | 720pSelects the output resolution or provider generation mode. Higher settings may take longer to process.

Output fields

FieldTypeDescription
objectsarrayDetected heads: obj_id, preview url, masked_url, coverage, representative_frame, bbox
video_infoobjectInput video info: width/height/fps/frame_count
analysis_idstringAnalysis session id
detected_objectsnumberNumber of detected heads
track_manifest_urlstringTrack manifest URL - pass it to the generate model

API

Call this model through one unified REST API. Get a key on the API Keys page.

cURL
# 1) Submit — returns { "task_uuid": "..." }
curl -X POST "https://www.namifusion.com/api/v1/marketplace/run/namifusion/head-swap/analyze" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "input": {
    "resolution": "720p"
  }
}'

# 2) Poll until status is "completed", then read the output URLs
curl "https://www.namifusion.com/api/v1/marketplace/run/tasks/TASK_UUID" \
  -H "Authorization: Bearer YOUR_API_KEY"
Python
import time, requests

API_KEY = "YOUR_API_KEY"
HEADERS = {"Authorization": f"Bearer {API_KEY}"}

# 1) Submit
resp = requests.post(
    "https://www.namifusion.com/api/v1/marketplace/run/namifusion/head-swap/analyze",
    headers=HEADERS,
    json={
        "input": {
            "resolution": "720p"
        }
    },
)
resp.raise_for_status()  # 401/402/429/5xx stop here instead of polling a bad task
task = resp.json()

# 2) Poll until a terminal state (completed / failed / cancelled).
#    This model is allowed up to 1800s server-side.
deadline = time.time() + 1860
while task.get("status") not in ("completed", "failed", "cancelled"):
    if time.time() > deadline:
        raise TimeoutError(f"still {task.get('status')} — keep the task_uuid and poll later")
    time.sleep(3)
    poll = requests.get(f"https://www.namifusion.com/api/v1/marketplace/run/tasks/{task['task_uuid']}", headers=HEADERS)
    poll.raise_for_status()
    task = poll.json()

print(task["status"], task.get("output"))
JavaScript
const API_KEY = "YOUR_API_KEY";
const HEADERS = { Authorization: `Bearer ${API_KEY}` };

// 1) Submit
const resp = await fetch("https://www.namifusion.com/api/v1/marketplace/run/namifusion/head-swap/analyze", {
  method: "POST",
  headers: { ...HEADERS, "Content-Type": "application/json" },
  body: JSON.stringify({
    "input": {
      "resolution": "720p"
    }
  }),
});
if (!resp.ok) throw new Error(`submit failed: ${resp.status} ${await resp.text()}`);
let task = await resp.json();

// 2) Poll until a terminal state (completed / failed / cancelled).
//    This model is allowed up to 1800s server-side.
const deadline = Date.now() + 1860 * 1000;
while (!["completed", "failed", "cancelled"].includes(task.status)) {
  if (Date.now() > deadline) throw new Error(`still ${task.status} — keep the task_uuid and poll later`);
  await new Promise((r) => setTimeout(r, 3000));
  const poll = await fetch(`https://www.namifusion.com/api/v1/marketplace/run/tasks/${task.task_uuid}`, { headers: HEADERS });
  if (!poll.ok) throw new Error(`poll failed: ${poll.status}`);
  task = await poll.json();
}

console.log(task.status, task.output);

Documentation

Head Swap - Analyze

Detect and track heads in a video as the first stage of the Head Swap workflow.

Head Swap Analyze follows visible heads across the input video and creates the obj_id values and track_manifest_url required by the Generate stage. The result also includes previews and video metadata for review. This model does not produce the final swapped video, so keep the original video, resolution, and analysis output together as one workflow unit.

Key Features

  • Head detection and tracking: Identifies targets and builds tracking data across video frames.
  • Target selection previews: Returns each head's obj_id, preview, mask, and coverage in objects.
  • Generate-ready tracking data: Produces a track_manifest_url for Head Swap Generate.
  • Video metadata: Includes width, height, FPS, and frame count in video_info.
  • 480p and 720p analysis: Tracks targets at the same resolution used for generation.

Technical Specifications

ItemDetails
WorkflowHead Swap step 1
Required inputvideo_url
Maximum video length30 seconds
Resolution480p, 720p (default)
Main outputsobjects, track_manifest_url, video_info
Next modelnamifusion/head-swap/generate

Basic Workflow

  1. Send the video URL and selected resolution to namifusion/head-swap/analyze.
  2. Poll the task result endpoint until analysis completes.
  3. Review the previews in objects and select the head obj_id values to replace.
  4. Pass the same video, returned manifest, and selected IDs to Head Swap Generate.

Pricing

The existing Marketplace rate is 10 credits per analysis request. This documentation update does not change pricing.

Best Practices

Use a video no longer than 30 seconds with heads large enough to inspect clearly. Heavy blur, long occlusions, and frequent movement outside the frame make tracking less reliable. Always use the same video and resolution in Generate, and never combine a track_manifest_url from a different Analyze task.