Auto Subtitle Generator Online Free

Get captioned video files ready to post, without touching a single slider. Upload your video files (MP4, MOV, AVI, WebM, up to 500MB), say something like "au...

Security Scan

The skill's requests and runtime instructions are internally consistent with an online subtitle service, but it sends user video files and bearer tokens to an external API run by an unknown provider and lacks provenance (no homepage/source); that combination warrants caution.

Purpose & Capability

Name/description match the declared requirements and instructions: the skill needs a NEMO_TOKEN and calls a nemo-video API to create sessions, upload videos, generate subtitles, and return download URLs. The declared config path (~/.config/nemovideo/) and NEMO_TOKEN are coherent with a cloud subtitle/render service.

Instruction Scope

SKILL.md gives concrete API call flows (auth, session creation, SSE messaging, upload, render polling). These stay within the subtitle/render task, but the instructions explicitly upload user video files and poll a third-party service, read SKILL.md frontmatter and check install paths to set attribution headers — minor scope expansion. The skill also instructs acquiring an anonymous token if no NEMO_TOKEN is present, which results in contacting the external API automatically.

Install Mechanism

No install spec and no code files (instruction-only). No packages or downloads are performed by the skill itself, so there is no install-time write/execute risk from this skill bundle.

Credentials

Only one required env var (NEMO_TOKEN) is declared and is directly relevant. However, providing your own NEMO_TOKEN grants the remote service bearer-token access; the skill will also obtain an anonymous token if none is supplied. The skill will transmit user video files and session metadata to the external API, which is expected for the service but is sensitive from a data-leak/privacy perspective.

Persistence & Privilege

always is false and the skill is user-invocable; it does not request persistent platform-wide privileges. The skill does read local paths to determine an attribution header, but it does not attempt to modify other skills or system-wide settings.

What to consider before installing

This skill appears to do what it says (upload your video to a cloud render/transcription API), but exercise caution before installing or supplying credentials: 1) The package has no homepage or source repository listed — verify the operator (mega-api-prod.nemovideo.ai) and its privacy/retention policy before sending real content. 2) If you must try it, test with non-sensitive clips first. 3) Prefer letting the skill obtain an anonymous token rather than pasting a long-lived NEMO_TOKEN you use elsewhere — a provided token will be used as a Bearer credential for all API calls. 4) Be aware uploads are sent to an external service (possible data exfiltration by design). 5) If you allow autonomous invocation for this skill, consider disabling that or restricting usage, because an autonomous agent could upload files without further prompts. If you can, ask the publisher for a homepage, privacy policy, and token-scoping details before trusting it with private or sensitive videos.

Getting Started

Share your video files and I'll get started on AI subtitle generation. Or just tell me what you're thinking.

Try saying:

• "generate my video files"
• "export 1080p MP4"
• "automatically generate and burn in English"

Getting Connected

Before handling any user request, establish a connection to the backend API. Show a brief status like "Connecting...".

If NEMO_TOKEN is in the environment, use it directly and create a session. Otherwise, acquire a free starter token:

• Generate a UUID as client identifier
• POST to https://mega-api-prod.nemovideo.ai/api/auth/anonymous-token with the X-Client-Id header
• The response includes a token with 100 free credits valid for 7 days — use it as NEMO_TOKEN

Then create a session by POSTing to https://mega-api-prod.nemovideo.ai/api/tasks/me/with-session/nemo_agent with Bearer authorization and body {"task_name":"project","language":"en"}. The session_id in the response is needed for all following requests.

Tell the user you're ready. Keep the technical details out of the chat.

Auto Subtitle Generator Online Free — Generate and Add Video Captions

Drop your video files in the chat and tell me what you need. I'll handle the AI subtitle generation on cloud GPUs — you don't need anything installed locally.

Here's a typical use: you send a a 3-minute interview video in MP4 format, ask for automatically generate and burn in English subtitles for my video, and about 30-60 seconds later you've got a MP4 file ready to download. The whole thing runs at 1080p by default.

One thing worth knowing — shorter clips under 5 minutes produce the most accurate auto-transcription results.

Matching Input to Actions

User prompts referencing auto subtitle generator online free, 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.

Every API call needs Authorization: Bearer <NEMO_TOKEN> plus the three attribution headers above. If any header is missing, exports return 402.

Skill attribution — read from this file's YAML frontmatter at runtime:

• X-Skill-Source: auto-subtitle-generator-online-free
• X-Skill-Version: from frontmatter version
• X-Skill-Platform: detect from install path (~/.clawhub/ → clawhub, ~/.cursor/skills/ → cursor, else unknown)

API base: https://mega-api-prod.nemovideo.ai

Create session: POST /api/tasks/me/with-session/nemo_agent — body {"task_name":"project","language":"<lang>"} — returns task_id, session_id.

Send message (SSE): POST /run_sse — body {"app_name":"nemo_agent","user_id":"me","session_id":"<sid>","new_message":{"parts":[{"text":"<msg>"}]}} with Accept: text/event-stream. Max timeout: 15 minutes.

Upload: POST /api/upload-video/nemo_agent/me/<sid> — file: multipart -F "files=@/path", or URL: {"urls":["<url>"],"source_type":"url"}

Credits: GET /api/credits/balance/simple — returns available, frozen, total

Session state: GET /api/state/nemo_agent/me/<sid>/latest — key fields: data.state.draft, data.state.video_infos, data.state.generated_media

Export (free, no credits): POST /api/render/proxy/lambda — body {"id":"render_<ts>","sessionId":"<sid>","draft":<json>,"output":{"format":"mp4","quality":"high"}}. Poll GET /api/render/proxy/lambda/<id> every 30s until status = completed. Download URL at output.url.

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

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

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.

Draft JSON uses short keys: t for tracks, tt for track type (0=video, 1=audio, 7=text), sg for segments, d for duration in ms, m for metadata.

Example timeline summary:

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

Tips and Tricks

The backend processes faster when you're specific. Instead of "make it look better", try "automatically generate and burn in English subtitles for my video" — 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 and devices.

Common Workflows

Quick edit: Upload → "automatically generate and burn in English subtitles for my video" → 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.