violin 0.1.0a7

Open-source video dubbing — translate any video into 33 languages with native-sounding voice-over and synced subtitles.

🎻 Violin

Open-source video dubbing — translate any video into 33 languages with natural-sounding voice-over and synced subtitles.

🌐 Live demo · 📜 MIT License

Upload a video. Violin transcribes the speech, translates it, synthesizes a native-sounding voice-over in the target language, and remuxes it back into the video — fully aligned, with optional SRT subtitles.

Available as a CLI, a FastAPI web app, and a Claude Code skill.

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✨ Features

• 33 target languages with handpicked native-speaker voices for the 16 most-used ones (Cartesia Sonic 3 + ElevenLabs)
• In-video Q&A — ask questions about any moment in the dubbed video; answers use nearby subtitles plus sampled frames
• Natural-language voice picker — describe the voice you want, an LLM picks from the catalog
• 6 style profiles (experimental) — standard / kids / academic / casual / storyteller / news
• Pluggable stack — Together / OpenAI / ElevenLabs interchangeable for every stage, one YAML

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🚀 Quick start

Try it without installing anything

The live demo runs at https://violin-ai.com — drop a short clip in, get a dubbed video out in a few minutes.

Run locally

Requires Python 3.10+ and ffmpeg on PATH.

uv tool install --pre violin     # --pre needed while v0.1 is in alpha
export TOGETHER_API_KEY=...      # get one at https://api.together.ai (add to ~/.zshrc to persist)

Three ways to use it:

1. CLI — translate one file:

violin lecture.mp4 lecture_zh.mp4 --language Chinese

2. Web app — full REST API + browser UI:

violin-api
# → http://127.0.0.1:8000           (browser UI)
# → http://127.0.0.1:8000/docs      (interactive API docs)

3. Claude Code skill — invoke from any Claude Code session:

violin --install-skill          # one-time: copies the skill into ~/.claude/skills/
claude
> please use the violin skill to translate path/to/video.mp4 into Chinese

Run from source (for hacking on the pipeline)

git clone https://github.com/shang-zhu/violin.git
cd violin
uv sync
cp .env.example .env             # then fill in TOGETHER_API_KEY
uv run main.py lecture.mp4 lecture_zh.mp4 --language Chinese

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🎬 How Violin works

Video
  │
  ├─ ffmpeg ─────────────────────► Extract audio (16 kHz WAV)
  │
  ├─ Whisper Large v3 ────────────► Word-level timestamps → sentence segments
  │
  ├─ LLM (DeepSeek V4 Pro by default) ──► Translate each segment, respecting style profile
  │
  ├─ TTS (Cartesia Sonic 3 by default) ─► Synthesize dubbed audio per segment
  │
  └─ ffmpeg ─────────────────────► Speed-align video to dubbed audio,
                                    concat with freeze-frame fallback,
                                    single-pass AAC encode the audio track,
                                    write output mp4 + optional SRT

Key engineering decisions worth a look if you're forking:

• pipeline/transcriber.py — uses Whisper's word-level timestamps to split into precise sentence boundaries. Has a hallucination filter that re-uses Whisper's own no_speech_prob segment metadata (no hand-tuned heuristics).
• pipeline/merger.py — concatenates speed-adjusted video chunks, but builds the audio track once from concatenated PCM and encodes AAC at the end. This is the difference between "subtitles drift 1–2 s by the end of an 8 min video" and "perfectly synced throughout."
• pipeline/tts_*.py — Cartesia + ElevenLabs backends share an interface. ElevenLabs side ships 21 premade voices (multilingual via eleven_v3) plus 15 hand-picked native-speaker voices from the Voice Library.

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⚙️ Configuration

All defaults live in config/default.yaml. Override with --config my.yaml (only the keys you want to change need to appear in the override file — values deep-merge).

Switch providers

# config/default.yaml — pick the stack you want
models:
  transcription:
    provider: together                  # together | openai
    model: openai/whisper-large-v3      # together → openai/whisper-large-v3 | openai → whisper-1
  translation:
    provider: together                  # together | openai
    model: deepseek-ai/DeepSeek-V4-Pro  # together → deepseek-ai/DeepSeek-V4-Pro | openai → gpt-5.5
  tts:
    provider: together                  # together | elevenlabs | openai
    model: cartesia/sonic-3             # together → cartesia/sonic-3 | elevenlabs → eleven_v3 | openai → tts-1-hd

Production overrides

A starter config/prod.yaml is included for public deployments. It adds upload limits, serializes jobs, and caps ffmpeg concurrency. The included Dockerfile + docker-compose.yml + Caddyfile are how the live demo is hosted — docker compose up -d --build after filling .env is enough to put a copy of Violin behind auto-HTTPS on any Docker host.

Environment variables

Variable	When required	Description
TOGETHER_API_KEY	Recommended — covers every stage with the default config	Together AI API key
OPENAI_API_KEY	Any stage uses provider: openai	Covers whisper-1, GPT models, and tts-1
ELEVENLABS_API_KEY	TTS uses provider: elevenlabs	ElevenLabs API key
CORS_ORIGINS	Optional	Comma-separated allowed origins (default: *)

You only need keys for the providers you actually pick. Pure-OpenAI deployments (all stages on openai) work too — OPENAI_API_KEY alone is enough. Same idea for ElevenLabs.

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🎭 Style profiles

Six built-in profiles tune both the translation LLM prompt and the TTS delivery. Use --style <name> on the CLI or pass style in API requests.

Style	Tone	TTS speed	Emotion
standard	Faithful translation, natural voice	1.0×	—
kids	Rewritten for a 7-year-old, plain language	1.0×	excited
academic	Formal register, preserves jargon and honorifics	0.95×	calm
casual	Spoken slang, contractions, friendly	1.1×	content
storyteller	Vivid, dramatic narration	0.9×	enthusiastic
news	Concise, declarative, broadcast-style	1.0×	neutral

Add your own by editing prompts/styles.yaml.

See all available styles: violin --style list.

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💻 CLI usage

Examples use the PyPI-installed violin command. If you're running from a git checkout, substitute uv run main.py for violin (and uv run run_api.py for violin-api).

# Basic
violin lecture.mp4 lecture_es.mp4 --language Spanish

# Pick a style
violin talk.mp4 talk_zh.mp4 --language Chinese --style kids

# Pick a specific voice
violin lecture.mp4 lecture_fr.mp4 --language French --voice "french narrator man"

# Skip SRT
violin lecture.mp4 lecture_ja.mp4 --language Japanese --no-subtitles

# Full replacement (no original audio underneath)
violin lecture.mp4 lecture_ko.mp4 --language Korean --no-voiceover

# Custom config (e.g. switch to OpenAI/ElevenLabs)
violin lecture.mp4 lecture_it.mp4 --language Italian --config config/other_api.yaml

CLI flags

Flag	Default	Description
--language / -l	(required)	Target language name (e.g. Spanish, Japanese)
--voice / -v	auto	TTS voice. Defaults to the primary native voice for the target language
--source-language	auto-detect	Source language hint for translation
--no-subtitles	off	Skip SRT generation
--voiceover / --no-voiceover	voiceover on	Keep original audio underneath the dub, or full replacement
--style / -s	standard	Style profile name. Use --style list to see all
--config / -c	config/default.yaml	Path to a YAML override file
--timings-out	off	Write per-step wall-clock timings + cost as JSON

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🛰️ Web app & REST API

violin-api                              # default dev mode
violin-api --host 0.0.0.0 --port 8080   # bind everywhere
violin-api --config config/prod.yaml    # production overrides (requires a git checkout for config/prod.yaml)

Core flow: POST /jobs to start, GET /jobs/{id} to poll, GET /jobs/{id}/video and /srt to download, POST /jobs/{id}/chat for in-video Q&A. Full list with request/response schemas at /docs.

Example

# Submit
JOB=$(curl -s -X POST http://localhost:8000/jobs \
  -F "file=@lecture.mp4" \
  -F "language=Spanish" \
  -F "style=academic" | jq -r .id)

# Poll
curl -s http://localhost:8000/jobs/$JOB | jq '{status, progress}'

# Download
curl -OJ http://localhost:8000/jobs/$JOB/video
curl -OJ http://localhost:8000/jobs/$JOB/srt

Job data lives under jobs/{id}/. Set api.job_ttl_hours to auto-delete jobs older than N hours (default 0 = disabled; config/prod.yaml uses 24h for the public demo).

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🌍 Supported languages

Violin supports 33 target languages. The 16 below ship with handpicked native-speaker voices for each provider; the rest fall back to the English voice catalog (which is multilingual under both Cartesia Sonic 3 and ElevenLabs eleven_v3).

Ordered by native-speaker population.

Language	Cartesia native voice (M / F)	ElevenLabs native voice (M / F)
Chinese	chinese commercial man / chinese female conversational	Lin / Lingyue
Spanish	spanish narrator man / spanish narrator lady	Carlos / Valeria
English	tutorial man / helpful woman	Adam / Sarah
Hindi	hindi narrator man / hindi narrator woman	Yatin / Madhusmita
Arabic	middle eastern woman	Faris / Haneen
Portuguese	friendly brazilian man / pleasant brazilian lady	Medeiros / Luna
Russian	russian narrator man 1 / russian narrator woman	Ivo / Xenia
Japanese	japanese male conversational / japanese woman conversational	Shohei / Maiko
Turkish	turkish narrator man / turkish calm man	Sinan / Aura
German	german reporter man / german conversational woman	Daniel / Sina
Korean	korean narrator man / korean calm woman	Joon-ho / Soo
French	french narrator man / french narrator lady	Lior / Virginie
Italian	italian narrator man / italian narrator woman	Raffaele / Chiara
Polish	polish confident man / polish narrator woman	Gregor / Jola
Dutch	dutch confident man / dutch man	Ronald / Jolanda
Swedish	swedish narrator man / swedish calm lady	Andreas / Louise

The 17 fallback languages (using the English voice catalog), also ordered by native speakers: Vietnamese, Tamil, Indonesian, Malay, Ukrainian, Romanian, Thai, Greek, Hungarian, Catalan, Czech, Bulgarian, Danish, Slovak, Croatian, Finnish, Norwegian.

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🤝 Contributing

PRs welcome. Got questions or hit a bug? Email [e-mail] or open an issue.

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⚠️ Disclaimer

This is a personal open-source project, not a Together AI product. Users are responsible for ensuring they have the right to download and translate any content they process. Designed for Creative Commons, public domain, your own recordings, and other content you have permission to use.

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📜 License

MIT — use it freely, including commercially.

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🙏 Acknowledgements

Built on top of Together AI, Whisper, Cartesia Sonic 3, ElevenLabs, FastAPI, and ffmpeg.