Ai Subtitle Adder

add video files into captioned video files with this skill. Works with MP4, MOV, AVI, WebM files up to 500MB. YouTubers and content creators use it for addin...

Security Scan

The skill's requirements and runtime instructions are coherent with a cloud subtitle-rendering service; it asks for a single service token and instructs uploading videos to that service — the main remaining risks are privacy (uploading video) and the fact the service/source is unknown.

Purpose & Capability

The skill's name and description (auto-generate and burn-in subtitles) line up with its runtime actions: creating a session, uploading video, requesting renders, polling for results. The single required env var (NEMO_TOKEN) is appropriate for authorizing against the described backend.

Instruction Scope

Instructions direct the agent to upload user video files and call the described nemovideo.ai endpoints (session, upload, render, state, credits). This is expected for the stated purpose, but it does transmit users' media to a third-party cloud service. The SKILL.md also specifies an automatic anonymous-token flow (POST to /api/auth/anonymous-token) if NEMO_TOKEN is absent; this behavior is explicit and could result in anonymous credentials being created on the user's behalf.

Install Mechanism

No install spec and no code files (instruction-only) — nothing is downloaded or written to disk by the skill itself. This minimizes supply-chain risk.

Credentials

Only one environment variable (NEMO_TOKEN) is required and it directly maps to the described backend authentication. No unrelated credentials are requested. The README frontmatter references a config path (~/.config/nemovideo/) which is reasonable for a user-scoped service config, but the registry metadata listed no required config paths — a minor inconsistency (see guidance).

Persistence & Privilege

The skill does not request always:true or other elevated persistence. It can be invoked autonomously by the agent (default behavior) but does not request system-wide modifications or extra privileges.

Assessment

This skill appears to do what it says: it uploads videos to a cloud service (mega-api-prod.nemovideo.ai) to generate and return burned-in subtitles. Before installing or using it, consider: 1) Privacy — your videos (and any spoken content) are uploaded to a third-party backend; do not upload sensitive or private footage unless you trust the service and its policy. 2) Token behavior — if you don't provide NEMO_TOKEN the skill will automatically request an anonymous token (100 free credits, 7-day expiry); if you want account continuity, set NEMO_TOKEN to your own account token. 3) Unknown source — there is no homepage or source repo listed; that reduces auditability. 4) Config-path mismatch — the frontmatter mentions ~/.config/nemovideo/ but the registry metadata did not list required config paths; this is a minor inconsistency to be aware of. 5) Endpoint check — if you rely on this, verify the domain and review the service's privacy/terms if possible. If any of these concerns matter (especially privacy), do not use the skill or only use it with non-sensitive test videos.

Getting Started

Ready when you are. Drop your video files here or describe what you want to make.

Try saying:

• "add a 3-minute YouTube tutorial recording into a 1080p MP4"
• "add subtitles in English and Spanish with auto-sync"
• "adding subtitles to YouTube and social media videos for YouTubers and content creators"

Quick Start Setup

This skill connects to a cloud processing backend. On first use, set up the connection automatically and let the user know ("Connecting...").

Token check: Look for NEMO_TOKEN in the environment. If found, skip to session creation. Otherwise:

• Generate a UUID as client identifier
• POST https://mega-api-prod.nemovideo.ai/api/auth/anonymous-token with X-Client-Id header
• Extract data.token from the response — this is your NEMO_TOKEN (100 free credits, 7-day expiry)

Session: POST https://mega-api-prod.nemovideo.ai/api/tasks/me/with-session/nemo_agent with Bearer auth and body {"task_name":"project"}. Keep the returned session_id for all operations.

Let the user know with a brief "Ready!" when setup is complete. Don't expose tokens or raw API output.

AI Subtitle Adder — Auto-Generate and Burn In Subtitles

This tool takes your video files and runs AI subtitle generation through a cloud rendering pipeline. You upload, describe what you want, and download the result.

Say you have a 3-minute YouTube tutorial recording and want to add subtitles in English and Spanish with auto-sync — the backend processes it in about 30-60 seconds and hands you a 1080p MP4.

Tip: clear audio with minimal background noise produces the most accurate subtitles.

Matching Input to Actions

User prompts referencing ai subtitle adder, aspect ratio, text overlays, or audio tracks get routed to the corresponding action via keyword and intent classification.

User says...	Action	Skip SSE?
"export" / "导出" / "download" / "send me the video"	→ §3.5 Export	✅
"credits" / "积分" / "balance" / "余额"	→ §3.3 Credits	✅
"status" / "状态" / "show tracks"	→ §3.4 State	✅
"upload" / "上传" / user sends file	→ §3.2 Upload	✅
Everything else (generate, edit, add BGM…)	→ §3.1 SSE	❌

Cloud Render Pipeline Details

Each export job queues on a cloud GPU node that composites video layers, applies platform-spec compression (H.264, up to 1080x1920), and returns a download URL within 30-90 seconds. The session token carries render job IDs, so closing the tab before completion orphans the job.

All calls go to https://mega-api-prod.nemovideo.ai. The main endpoints:

1. Session — POST /api/tasks/me/with-session/nemo_agent with {"task_name":"project","language":"<lang>"}. Gives you a session_id.
2. Chat (SSE) — POST /run_sse with session_id and your message in new_message.parts[0].text. Set Accept: text/event-stream. Up to 15 min.
3. Upload — POST /api/upload-video/nemo_agent/me/<sid> — multipart file or JSON with URLs.
4. Credits — GET /api/credits/balance/simple — returns available, frozen, total.
5. State — GET /api/state/nemo_agent/me/<sid>/latest — current draft and media info.
6. Export — POST /api/render/proxy/lambda with render ID and draft JSON. Poll GET /api/render/proxy/lambda/<id> every 30s for completed status and download URL.

Formats: mp4, mov, avi, webm, mkv, jpg, png, gif, webp, mp3, wav, m4a, aac.

Headers are derived from this file's YAML frontmatter. X-Skill-Source is ai-subtitle-adder, X-Skill-Version comes from the version field, and X-Skill-Platform is detected from the install path (~/.clawhub/ = clawhub, ~/.cursor/skills/ = cursor, otherwise unknown).

All requests must include: Authorization: Bearer <NEMO_TOKEN>, X-Skill-Source, X-Skill-Version, X-Skill-Platform. Missing attribution headers will cause export to fail with 402.

Draft field mapping: t=tracks, tt=track type (0=video, 1=audio, 7=text), sg=segments, d=duration(ms), m=metadata.

Timeline (3 tracks): 1. Video: city timelapse (0-10s) 2. BGM: Lo-fi (0-10s, 35%) 3. Title: "Urban Dreams" (0-3s)

Backend Response Translation

The backend assumes a GUI exists. Translate these into API actions:

Backend says	You do
"click [button]" / "点击"	Execute via API
"open [panel]" / "打开"	Query session state
"drag/drop" / "拖拽"	Send edit via SSE
"preview in timeline"	Show track summary
"Export button" / "导出"	Execute export workflow

Reading the SSE Stream

Text events go straight to the user (after GUI translation). Tool calls stay internal. Heartbeats and empty data: lines mean the backend is still working — show "⏳ Still working..." every 2 minutes.

About 30% of edit operations close the stream without any text. When that happens, poll /api/state to confirm the timeline changed, then tell the user what was updated.

Error Codes

• 0 — success, continue normally
• 1001 — token expired or invalid; re-acquire via /api/auth/anonymous-token
• 1002 — session not found; create a new one
• 2001 — out of credits; anonymous users get a registration link with ?bind=<id>, registered users top up
• 4001 — unsupported file type; show accepted formats
• 4002 — file too large; suggest compressing or trimming
• 400 — missing X-Client-Id; generate one and retry
• 402 — free plan export blocked; not a credit issue, subscription tier
• 429 — rate limited; wait 30s and retry once

Common Workflows

Quick edit: Upload → "add subtitles in English and Spanish with auto-sync" → Download MP4. Takes 30-60 seconds for a 30-second clip.

Batch style: Upload multiple files in one session. Process them one by one with different instructions. Each gets its own render.

Iterative: Start with a rough cut, preview the result, then refine. The session keeps your timeline state so you can keep tweaking.

Tips and Tricks

The backend processes faster when you're specific. Instead of "make it look better", try "add subtitles in English and Spanish with auto-sync" — concrete instructions get better results.

Max file size is 500MB. Stick to MP4, MOV, AVI, WebM for the smoothest experience.

Export as MP4 for widest compatibility across platforms.