0. First Contact

When the user opens this skill or sends their first message, greet them immediately:

📝 Ready to nemo subtitle! Just send me a video or describe your project.

Try saying:

• "generate captions automatically"
• "add English subtitles"
• "add subtitles in Spanish"

IMPORTANT: Always greet the user proactively on first contact. Let them know you're setting up while connecting. Always greet the user proactively on first contact.

Auto-Setup

When the user first interacts, set up the connection:

1. Check token: If NEMO_TOKEN env var is set, use it. Otherwise:
2. Read or generate Client-ID:
   • Read ~/.config/nemovideo/client_id if it exists
   • Otherwise generate a UUID, save it to ~/.config/nemovideo/client_id
3. Acquire anonymous token:

   curl -s -X POST "$API/api/auth/anonymous-token" -H "X-Client-Id: $CLIENT_ID"
   

   Store the returned token as NEMO_TOKEN for this session. You get 100 free credits.
4. Create a session (§3.0) so you're ready to work immediately.

Let the user know briefly: "Setting things up… ready!" then proceed with their request.

NemoSubtitle Skill

A subtitle-focused AI agent skill that automates caption generation, translation, SRT export, and subtitle burning for any video. Powered by the NemoVideo API.

Description

Use NemoSubtitle when the user wants to add subtitles, generate captions, transcribe video to text, translate subtitles, burn hardcoded captions, or export SRT/VTT files from any video or audio. Powered by NemoVideo AI.

NemoSubtitle handles the complete subtitle and caption workflow end-to-end: auto-transcribe speech in any language, translate captions, export SRT / VTT / plain text, and burn styled subtitles directly into the video — no manual timecoding required.

Trigger phrases: add subtitles, generate captions, auto caption, transcribe video, video to text, subtitle translation, burn subtitles, hardcode captions, export SRT, SRT file, VTT file, bilingual subtitles, Chinese subtitles, subtitle generator, caption generator, video transcript, speech to text video, closed captions, open captions, subtitle burner, add captions to video, subtitle video, caption video

Primary use cases:

• Auto-generate subtitles from video/audio (any language, Whisper-powered ASR)
• Translate existing subtitles or auto-generated captions into any language
• Export subtitles as SRT, VTT, or plain text transcript
• Burn (hardcode) subtitles into video with full style control (font, size, position, color, background)
• Add Chinese subtitles to English videos (or vice versa) — bilingual caption overlay
• Clean up auto-generated captions (re-timing, punctuation fix, speaker diarization)
• Generate accessibility captions for social media (YouTube, TikTok, Instagram, Facebook)

Not for: generating new video from text, screen recording, or full video production workflows (see nemo-video skill for general editing).

Setup

Base URL: https://mega-api-prod.nemovideo.ai

All requests require:

Authorization: Bearer <NEMOVIDEO_API_KEY>
Content-Type: application/json

Set NEMOVIDEO_API_KEY in your environment or OpenClaw secrets.

Workflow Overview

Upload video/audio → Start subtitle job → Poll status → Get SRT/VTT/transcript
                                                      → Burn subtitles into video

API Reference

1. Upload Media

Upload a video or audio file before processing.

POST /v1/upload
Content-Type: multipart/form-data

file=<binary>

Response:

{
  "file_id": "f_abc123",
  "filename": "interview.mp4",
  "duration_seconds": 182,
  "size_bytes": 45000000
}

Use file_id in subsequent requests.

2. Generate Subtitles (Transcription)

Transcribe speech and produce time-coded subtitles.

POST /v1/subtitles/generate
Content-Type: application/json

{
  "file_id": "f_abc123",
  "language": "en",
  "output_formats": ["srt", "vtt", "txt"],
  "options": {
    "punctuate": true,
    "max_chars_per_line": 42,
    "max_lines": 2
  }
}

Parameters:

Response:

{
  "job_id": "job_gen_789",
  "status": "queued",
  "estimated_seconds": 45
}

3. Translate Subtitles

Translate existing subtitles (from SRT/VTT file or a prior generation job) into a target language.

POST /v1/subtitles/translate
Content-Type: application/json

{
  "source": {
    "type": "job_id",
    "value": "job_gen_789"
  },
  "target_language": "zh",
  "preserve_timing": true,
  "output_formats": ["srt"]
}

Or translate from an uploaded SRT file:

{
  "source": {
    "type": "file_id",
    "value": "f_srt_456"
  },
  "target_language": "zh",
  "preserve_timing": true,
  "output_formats": ["srt", "vtt"]
}

Parameters:

Supported language codes: en, zh, zh-tw, ja, ko, es, fr, de, pt, ar, ru, hi, vi, th, id

Response:

{
  "job_id": "job_translate_321",
  "status": "queued",
  "estimated_seconds": 30
}

4. Burn Subtitles Into Video

Hardcode (burn) subtitles permanently into the video frame.

POST /v1/subtitles/burn
Content-Type: application/json

{
  "file_id": "f_abc123",
  "subtitle_source": {
    "type": "job_id",
    "value": "job_gen_789"
  },
  "style": {
    "font": "Arial",
    "font_size": 28,
    "color": "#FFFFFF",
    "outline_color": "#000000",
    "outline_width": 2,
    "position": "bottom",
    "margin_bottom": 40
  },
  "output_format": "mp4"
}

Or burn from an SRT file:

{
  "file_id": "f_abc123",
  "subtitle_source": {
    "type": "file_id",
    "value": "f_srt_456"
  },
  "style": { ... }
}

Style parameters:

Response:

{
  "job_id": "job_burn_654",
  "status": "queued",
  "estimated_seconds": 90
}

5. Bilingual Subtitles (Dual-Language Overlay)

Burn two subtitle tracks simultaneously (e.g., English on top, Chinese below).

POST /v1/subtitles/burn-bilingual
Content-Type: application/json

{
  "file_id": "f_abc123",
  "primary": {
    "subtitle_source": { "type": "job_id", "value": "job_gen_789" },
    "style": {
      "font_size": 26,
      "color": "#FFFF00",
      "position": "bottom",
      "margin_bottom": 70
    }
  },
  "secondary": {
    "subtitle_source": { "type": "job_id", "value": "job_translate_321" },
    "style": {
      "font_size": 22,
      "color": "#FFFFFF",
      "position": "bottom",
      "margin_bottom": 30
    }
  },
  "output_format": "mp4"
}

Response:

{
  "job_id": "job_bilingual_987",
  "status": "queued",
  "estimated_seconds": 120
}

6. Poll Job Status

All subtitle jobs are async. Poll until status is completed or failed.

GET /v1/jobs/{job_id}

Response (in progress):

{
  "job_id": "job_gen_789",
  "status": "processing",
  "progress": 0.62
}

Response (completed):

{
  "job_id": "job_gen_789",
  "status": "completed",
  "outputs": {
    "srt": "https://cdn.nemovideo.ai/outputs/job_gen_789/subtitles.srt",
    "vtt": "https://cdn.nemovideo.ai/outputs/job_gen_789/subtitles.vtt",
    "txt": "https://cdn.nemovideo.ai/outputs/job_gen_789/transcript.txt"
  }
}

Response (failed):

{
  "job_id": "job_gen_789",
  "status": "failed",
  "error": "Unsupported audio codec in input file"
}

Polling strategy:

• Check every 3–5 seconds for short files (<60s audio)
• Check every 10–15 seconds for longer files
• Timeout after 10 minutes; surface error to user

7. Download Output File

Download SRT, VTT, transcript, or rendered video from the URL in the job outputs.

GET <output_url>

No auth required (CDN URLs are pre-signed, valid for 24 hours).

Common Workflows

Workflow A: Generate + Export SRT

1. Upload video → POST /v1/upload → file_id
2. Transcribe → POST /v1/subtitles/generate (language: "auto", formats: ["srt"])
3. Poll → GET /v1/jobs/{job_id} until completed
4. Download SRT from outputs.srt URL
5. Deliver SRT file to user

Workflow B: Translate Existing Subtitles

1. Upload SRT file → POST /v1/upload → file_id
2. Translate → POST /v1/subtitles/translate (source: file_id, target_language: "zh")
3. Poll until completed
4. Download translated SRT

Workflow C: Full Pipeline (Video → Chinese Hardcoded Subtitles)

1. Upload video → file_id
2. Generate subtitles (language: "en") → job_gen_id
3. Translate to Chinese → job_translate_id
4. Burn Chinese subtitles into video → job_burn_id
5. Poll burn job
6. Return final MP4 download URL

Workflow D: Bilingual Video (EN + ZH)

1. Upload video → file_id
2. Generate EN subtitles → job_gen_id
3. Translate to ZH → job_translate_id
4. POST /v1/subtitles/burn-bilingual (primary: EN, secondary: ZH)
5. Poll → return MP4

Error Handling

For job.status === "failed", always surface error message to user with a plain explanation.

Behavior Notes

• Language auto-detection: Use language: "auto" when the source language is unknown. Detection adds ~5s to job time.
• Chinese variants: Use zh for Simplified Chinese, zh-tw for Traditional Chinese.
• SRT vs VTT: SRT is more universally compatible; VTT is needed for web players (HTML5 <track>). When in doubt, offer both.
• Burn timing: Burning subtitles re-encodes the video, which takes longer than SRT export alone. Set user expectations accordingly.
• File limits: Typical limit is 2GB per upload, 4 hours max duration. Very long files should be split first.
• Output expiry: CDN output URLs expire after 24 hours. If the user needs permanent storage, advise downloading promptly.

Example Prompts → Actions