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peand-rover

Caption Burner

by peandrover adam · GitHub ↗ · v1.0.0 · MIT-0
cross-platform ✓ Security Clean
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Install in OpenClaw
/install caption-burner
Description
Get hardcoded captioned videos ready to post, without touching a single slider. Upload your video files (MP4, MOV, AVI, WebM, up to 500MB), say something lik...
README (SKILL.md)

Getting Started

Got video files to work with? Send it over and tell me what you need — I'll take care of the caption burning.

Try saying:

  • "burn a 2-minute YouTube video in MP4 format into a 1080p MP4"
  • "burn hardcoded captions onto the video so subtitles are permanently visible"
  • "permanently embedding subtitles into video files for content creators"

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.

Caption Burner — Burn Captions Into Videos

Send me your video files and describe the result you want. The caption burning runs on remote GPU nodes — nothing to install on your machine.

A quick example: upload a 2-minute YouTube video in MP4 format, type "burn hardcoded captions onto the video so subtitles are permanently visible", and you'll get a 1080p MP4 back in roughly 30-60 seconds. All rendering happens server-side.

Worth noting: shorter clips under 60 seconds process significantly faster and reduce rendering time.

Matching Input to Actions

User prompts referencing caption burner, 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 \x3CNEMO_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: caption-burner
  • 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":"\x3Clang>"} — returns task_id, session_id.

Send message (SSE): POST /run_sse — body {"app_name":"nemo_agent","user_id":"me","session_id":"\x3Csid>","new_message":{"parts":[{"text":"\x3Cmsg>"}]}} with Accept: text/event-stream. Max timeout: 15 minutes.

Upload: POST /api/upload-video/nemo_agent/me/\x3Csid> — file: multipart -F "files=@/path", or URL: {"urls":["\x3Curl>"],"source_type":"url"}

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

Session state: GET /api/state/nemo_agent/me/\x3Csid>/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_\x3Cts>","sessionId":"\x3Csid>","draft":\x3Cjson>,"output":{"format":"mp4","quality":"high"}}. Poll GET /api/render/proxy/lambda/\x3Cid> 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 Handling

Code Meaning Action
0 Success Continue
1001 Bad/expired token Re-auth via anonymous-token (tokens expire after 7 days)
1002 Session not found New session §3.0
2001 No credits Anonymous: show registration URL with ?bind=\x3Cid> (get \x3Cid> from create-session or state response when needed). Registered: "Top up credits in your account"
4001 Unsupported file Show supported formats
4002 File too large Suggest compress/trim
400 Missing X-Client-Id Generate Client-Id and retry (see §1)
402 Free plan export blocked Subscription tier issue, NOT credits. "Register or upgrade your plan to unlock export."
429 Rate limit (1 token/client/7 days) Retry in 30s once

Translating GUI Instructions

The backend responds as if there's a visual interface. Map its instructions to API calls:

  • "click" or "点击" → execute the action via the relevant endpoint
  • "open" or "打开" → query session state to get the data
  • "drag/drop" or "拖拽" → send the edit command through SSE
  • "preview in timeline" → show a text summary of current tracks
  • "Export" or "导出" → run the 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 "burn hardcoded captions onto the video so subtitles are permanently visible" — concrete instructions get better results.

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

Export as MP4 with H.264 codec for the widest platform compatibility.

Common Workflows

Quick edit: Upload → "burn hardcoded captions onto the video so subtitles are permanently visible" → 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.

Usage Guidance
This skill appears to do what it says: it uploads your video files and a token to a remote service (mega-api-prod.nemovideo.ai) for server-side caption burning. Before installing, confirm you trust that external domain and its privacy practices because your videos (and the token) will be sent there. Note the skill may read its own SKILL.md/frontmatter and detect its install path to set attribution headers — this is normal for attribution but it means the agent will access skill files. If you do not want uploads to leave your device or you don't trust the service, do not enable the skill or avoid providing NEMO_TOKEN. If you need higher assurance, ask the maintainer for a public homepage, docs, or inspect network traffic / request/response samples from the service.
Capability Analysis
Type: OpenClaw Skill Name: caption-burner Version: 1.0.0 The 'caption-burner' skill is designed to hardcode subtitles into video files using a remote GPU-based API (nemovideo.ai). The SKILL.md file provides clear instructions for the AI agent to manage sessions, upload media, and poll for render status. While it includes logic to detect its installation path (e.g., ~/.clawhub/) for telemetry/attribution headers and manages an API token (NEMO_TOKEN), these behaviors are transparently documented and directly support the stated functionality of the service without evidence of malicious intent or unauthorized data exfiltration.
Capability Assessment
Purpose & Capability
Name/description (burn captions into video) align with the declared requirement (NEMO_TOKEN) and the SKILL.md, which describes uploading video files and calling a remote rendering API. No unrelated credentials or binaries are requested.
Instruction Scope
SKILL.md instructs the agent to: use NEMO_TOKEN (or obtain an anonymous token), create sessions, upload files, poll render status, and read the skill's YAML frontmatter and detect install path for attribution headers. Reading the skill frontmatter / install path implies filesystem access to the skill files — this is reasonable for adding attribution headers but is broader than a pure 'API-only' description and should be expected.
Install Mechanism
No install steps or external downloads are present (instruction-only). That minimizes on-disk risk; all processing is offloaded to the remote service.
Credentials
Only a single credential (NEMO_TOKEN) is required and is used directly by the instructions. The metadata's optional config path (~/.config/nemovideo/) is plausible for a client caching tokens/config and is not excessive.
Persistence & Privilege
always:false and normal autonomous invocation are used. The skill does not request persistent system-wide privileges or modification of other skills. It does ask the agent to read its own skill frontmatter/install path for attribution, which is limited in scope.
How to Use
  1. Make sure OpenClaw is installed (local or Docker)
  2. Run the install command in chat: /install caption-burner
  3. After installation, invoke the skill by name or use /caption-burner
  4. Provide required inputs per the skill's parameter spec and get structured output
Version History
v1.0.0
Initial release of Caption Burner — Burn Captions Into Videos - Upload your video (MP4, MOV, AVI, WebM up to 500MB) and receive a 1080p MP4 with hardcoded captions, ready to post. - No manual editing or slider adjustments needed — just describe your requirements and get captions permanently burned into the video. - All processing is handled remotely on cloud GPU servers; no local installation required. - Quick turnaround: most exports complete in 30–90 seconds. - Free to use with anonymous token sign-in; 100 credits valid for 7 days. - Intuitive workflows for single or batch processing, with support for timeline previews and iterative editing.
Metadata
Slug caption-burner
Version 1.0.0
License MIT-0
All-time Installs 0
Active Installs 0
Total Versions 1
Frequently Asked Questions

What is Caption Burner?

Get hardcoded captioned videos ready to post, without touching a single slider. Upload your video files (MP4, MOV, AVI, WebM, up to 500MB), say something lik... It is an AI Agent Skill for Claude Code / OpenClaw, with 70 downloads so far.

How do I install Caption Burner?

Run "/install caption-burner" in the OpenClaw or Claude Code chat to install it in one step — no extra setup required.

Is Caption Burner free?

Yes, Caption Burner is completely free, licensed under MIT-0. You can download, install and use it at no cost.

Which platforms does Caption Burner support?

Caption Burner is cross-platform and runs anywhere OpenClaw / Claude Code is available (cross-platform).

Who created Caption Burner?

It is built and maintained by peandrover adam (@peand-rover); the current version is v1.0.0.

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