How To Add Music To Video Online

add video and audio files into music-backed videos with this skill. Works with MP4, MOV, AVI, MP3 files up to 500MB. content creators use it for adding backg...

Security Scan

The skill is internally consistent with its stated purpose: it uses a NEMO backend API to merge audio into video, only requests a single service token (NEMO_TOKEN), and contains instructions to obtain and use anonymous tokens and session IDs for uploads/exports.

Purpose & Capability

Name/description match the runtime instructions: the SKILL.md exclusively describes calling the nemo backend (mega-api-prod.nemovideo.ai) to upload media, create render jobs, poll status, and return download URLs. Requiring NEMO_TOKEN and a nemovideo config path is coherent for a client that talks to that service.

Instruction Scope

Instructions include normal client actions (POST anonymous-token, create session, upload files, SSE for streaming responses, poll render status). They also instruct detecting the agent install path to set an X-Skill-Platform header and to read the skill's YAML frontmatter for attribution headers; these actions require reading some local state but are explainable for attribution. The skill tells the agent to store session_id (and implicitly keep/use tokens) and to avoid showing raw tokens to users. This is expected, but users should be aware the skill will send their uploaded media and metadata to an external service.

Install Mechanism

This is an instruction-only skill with no install spec and no code files — lowest disk/write risk. No remote downloads or third-party package installs are present.

Credentials

Only one environment variable is required (NEMO_TOKEN) and it is the primary credential for the described API. The declared config path (~/.config/nemovideo/) is consistent with storing service/session state. There are no unrelated secrets requested.

Persistence & Privilege

The skill will obtain and reuse an anonymous token if NEMO_TOKEN is not set, and it directs storing session_id (and implies persisting state under the nemovideo config path). It does not request always:true or any global privileges, but it will maintain session state and upload user media to the external service — users should expect persisted tokens/IDs tied to their uploads.

Assessment

This skill appears to do what it says, but it will upload your video/audio to an external service (mega-api-prod.nemovideo.ai) and may persist anonymous tokens/session IDs (likely under ~/.config/nemovideo/). Before installing: (1) confirm you trust that external domain and its privacy/data-retention policy — do not upload sensitive content unless you are comfortable with the service; (2) if you prefer control, set a token yourself in NEMO_TOKEN rather than allowing the skill to auto-generate and persist one; (3) be aware the skill may include attribution headers that reveal the agent install path and skill version; (4) because the skill source is unknown, consider testing with non-sensitive sample media first and monitor network activity; and (5) if you need a higher assurance, request the skill source or official publisher information before use.

Getting Started

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

Try saying:

• "add a 2-minute MP4 clip and an MP3 background track into a 1080p MP4"
• "add this background music to my video and fade it out at the end"
• "adding background music to videos online for content creators"

First-Time Connection

When a user first opens this skill, connect to the processing backend automatically. Briefly let them know (e.g. "Setting up...").

Authentication: Check if NEMO_TOKEN is set in the environment. If it is, skip to step 2.

1. Obtain a free token: Generate a random UUID as client identifier. POST to https://mega-api-prod.nemovideo.ai/api/auth/anonymous-token with header X-Client-Id set to that UUID. The response data.token is your NEMO_TOKEN — 100 free credits, valid 7 days.
2. Create a session: POST to https://mega-api-prod.nemovideo.ai/api/tasks/me/with-session/nemo_agent with Authorization: Bearer <token>, Content-Type: application/json, and body {"task_name":"project","language":"<detected>"}. Store the returned session_id for all subsequent requests.

Keep setup communication brief. Don't display raw API responses or token values to the user.

How to Add Music to Video Online — Add Music and Export Videos

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

Say you have a 2-minute MP4 clip and an MP3 background track and want to add this background music to my video and fade it out at the end — the backend processes it in about 20-40 seconds and hands you a 1080p MP4.

Tip: trim your audio to match the video length before uploading for a cleaner result.

Matching Input to Actions

User prompts referencing how to add music to video online, 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: how-to-add-music-to-video-online
• 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 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=<id> (get <id> 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

SSE Event Handling

Event	Action
Text response	Apply GUI translation (§4), present to user
Tool call/result	Process internally, don't forward
heartbeat / empty data:	Keep waiting. Every 2 min: "⏳ Still working..."
Stream closes	Process final response

~30% of editing operations return no text in the SSE stream. When this happens: poll session state to verify the edit was applied, then summarize changes to the user.

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)

Tips and Tricks

The backend processes faster when you're specific. Instead of "make it look better", try "add this background music to my video and fade it out at the end" — concrete instructions get better results.

Max file size is 500MB. Stick to MP4, MOV, AVI, MP3 for the smoothest experience.

Export as MP4 for widest compatibility.

Common Workflows

Quick edit: Upload → "add this background music to my video and fade it out at the end" → Download MP4. Takes 20-40 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.