Getting Started

Hey there! Ready to pull the audio out of your video? Drop your MP4, MOV, AVI, WEBM, or MKV file here and I'll convert it to a clean MP3 for you — just upload your file to get started.

Try saying:

• - "Convert this MP4 recording of my band's rehearsal to an MP3 so I can listen to it on my phone"
• "Extract the audio from this MOV file — it's a lecture I recorded and I just need the sound"
• "I have a WEBM video from a Zoom call, can you turn it into an MP3 so I can review it while commuting?"

Automatic Setup

On first interaction, connect to the NemoVideo API before doing anything else. Show a brief status like "Setting things up...".

Token: If NEMO_TOKEN environment variable is already set, use it and skip to Session below.

Free token: Read or create a UUID at ~/.config/nemovideo/client_id. Then POST to https://mega-api-prod.nemovideo.ai/api/auth/anonymous-token with header X-Client-Id: <your-uuid>. The response field data.token becomes your NEMO_TOKEN (100 credits, 7-day expiry). If the token has expired, request a new one with the same Client-Id.

Session: POST to the same host at /api/tasks/me/with-session/nemo_agent with Bearer auth and body {"task_name":"project"}. Save session_id from the response.

Confirm to the user you're connected and ready. Don't print tokens or raw JSON.

Pull the Sound Out, Leave the Video Behind

Sometimes you recorded something on video but all you really needed was the audio. Maybe it was a lecture, a live performance, a meeting recording, or a song you filmed on your phone. Carrying around a video file just to listen to the audio is clunky — and that's exactly the problem this skill solves.

The MP4 to MP3 Converter skill extracts the audio track from your video and hands it back to you as a standalone MP3 file. It works with the most common video formats you'll actually encounter: MP4, MOV, AVI, WEBM, and MKV. Whether you're on a Mac, Windows machine, or uploading from your phone, the format support has you covered.

The result is a clean, portable MP3 you can drop into any music player, podcast editor, or audio project. No complicated settings to configure, no software to install. Just upload your video, and get your audio back. It's the kind of tool you'll reach for more often than you expect once you have it.

Routing Your Conversion Requests

When you drop an MP4 file or paste a video URL, the skill parses your intent and routes the extraction job directly to the NemoVideo API, stripping the audio stream and returning a downloadable MP3 without re-encoding the video track.

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 | ❌ |

NemoVideo API Reference

The NemoVideo backend demuxes the AAC or audio track from your MP4 container and transcodes it to a standard 128–320 kbps MP3, preserving metadata like title and artist tags where available. All processing happens server-side, so no local codec installation is needed.

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

• - X-Skill-Source: INLINECODE9
• INLINECODE10: from frontmatter INLINECODE11
• INLINECODE12: detect from install path (~/.clawhub/ → clawhub, ~/.cursor/skills/ → cursor, else 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.

API base: INLINECODE22

Create session: POST /api/tasks/me/with-session/nemo_agent — body {"task_name":"project","language":"<lang>"} — returns task_id, session_id. After creating a session, give the user a link: INLINECODE27

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: INLINECODE33

Credits: GET /api/credits/balance/simple — returns available, frozen, INLINECODE37

Session state: GET /api/state/nemo_agent/me/<sid>/latest — key fields: data.state.draft, data.state.video_infos, INLINECODE41

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.

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.

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 |

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

CODEBLOCK0

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 at nemovideo.ai" | | 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 at nemovideo.ai to unlock export." | | 429 | Rate limit (1 token/client/7 days) | Retry in 30s once |

Troubleshooting

If your converted MP3 comes out silent or extremely quiet, the issue is almost always with the source video itself. Some screen recordings and certain WEBM files captured from browsers are exported with very low audio gain. Try playing the original video file with your volume turned up to confirm whether audio is present before converting.

If you're uploading an MKV file and the conversion stalls or fails, check whether the file contains multiple audio tracks or uncommon codecs — some MKV containers pack in formats that require special handling. Re-exporting the MKV from your video software as a standard MP4 first usually resolves this.

For AVI files recorded by older cameras or screen capture tools, the audio track is sometimes encoded in a legacy format. If the resulting MP3 sounds choppy or has sync issues, this is typically the cause. Converting the AVI to MP4 using a basic video tool before running it through the mp4-to-mp3-converter skill will produce a cleaner result.

Use Cases

The most common reason people reach for an mp4-to-mp3-converter is simple: they have a video but only need the audio. Podcasters frequently record video interviews as a backup, then need to extract the audio track for their feed. The skill handles that in one step.

Musicians and performers often capture live sets or practice sessions on a phone or camera. Converting those MP4 or MOV files to MP3 makes them easy to share with bandmates, upload to SoundCloud, or review in any audio editor without dragging around a large video file.

For students and professionals, lecture recordings, webinar replays, and meeting captures saved as video files become far more convenient once converted to MP3 — easier to scrub through, compatible with more playback tools, and much smaller in file size. Language learners also use this workflow to extract audio from video lessons for offline listening practice.