rusa 0.2.0

CLI tool for AI voiceover translation from subtitles

rusa — AI Voiceover for Movies & Videos

rusa is a CLI tool that creates a translated voiceover track from subtitles and mixes it into a video or exports audio-only output.

Project status

• Primary interface: CLI only
• Current focus: core pipeline, CLI UX, tests, docs, packaging
• Best-tested environment: Linux/macOS with ffmpeg and ffprobe in PATH
• Windows: best-effort support; use py -m pip install rusa and make sure ffmpeg.exe is in PATH

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Quick start

Install

# Linux / macOS
pip install rusa
sudo apt install ffmpeg       # or: brew install ffmpeg

# Windows
py -m pip install rusa
# Download ffmpeg.exe from https://ffmpeg.org and add it to PATH

Run

rusa movie.mkv

By default, rusa writes the result next to the source file, for example:

movie_edge-tts_ru.mkv

Quick health check

rusa --doctor

This prints a short report about:

• Python interpreter
• platform and console encoding
• ffmpeg / ffprobe
• edge-tts
• available TTS engines
• cache directory

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Common examples

# Basic run
rusa movie.mkv

# Use an external subtitle file
rusa -s subs.srt movie.mkv

# Choose subtitle language explicitly
rusa --lang he movie.mkv

# Use a specific voice
rusa --voice ru-RU-DmitryNeural movie.mkv

# Audio only
rusa --mp3 128 --audio-only movie.mkv

# Preview only the first 10 subtitle lines
rusa --preview 10 --dry-run movie.mkv

# Higher quality output for YouTube-style upload
rusa --preset youtube movie.mkv

# Auto-speed — each subtitle is accelerated just enough to fit its timeslot
rusa --speed auto movie.mkv

# Auto-speed with a custom upper limit
rusa --speed auto:max=2.0 movie.mkv

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How it works

1. Load subtitles from the video or an external .srt file
2. Optionally synchronize them with alass
3. Generate TTS audio per subtitle line
4. Convert TTS output to WAV and trim silence
5. Assemble all subtitle segments into one voiceover track
6. Mix the voiceover with the original audio
7. Encode the final output

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CLI options

Flag	Meaning	Default
video	Input video file	required
-o, --output FILE	Output file path	auto-generated
-s, --srt FILE	External subtitle file	auto-detect / extract
--voice [VOICE]	TTS voice; without value, list voices	auto
--lang LANG	Subtitle language code	auto
--speed SPEED	TTS speech speed; auto for per-segment tuning	1.5
--orig-vol VOL	Original audio volume	0.65
--tts-vol VOL	Voiceover volume	0.93
--sync	Synchronize subtitles with alass	off
--keep-temp	Keep temporary files	off
--threads N	TTS worker count	6
--cache-stats	Show cache statistics and exit	off
--cache-clear	Clear cache and exit	off
--no-cache	Disable cache for this run	off
--dry-run	Print plan only	off
--preview N	Process only first N subtitle lines	off
--overwrite	Overwrite existing output file	off
--aac [BITRATE]	Encode as AAC	off
--mp3 [BITRATE]	Encode as MP3	off
--opus [BITRATE]	Encode as Opus	default codec
--ac3 [BITRATE]	Encode as AC3	off
--from N	First subtitle index	all
--to N	Last subtitle index	all
--audio-only	Write audio output only	off
--engine ENGINE	TTS engine	edge
--tts-cmd TEMPLATE	Custom TTS command template	off
--subs-mode MODE	Subtitle handling: auto, copy, convert, drop	auto
--normalize [fast|fine]	Normalize output loudness	off
--preset NAME	Quality preset: youtube, tiktok, podcast, cinema	off
--doctor	Check local runtime dependencies and environment, then exit	off
--version	Show version and exit	—

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Docker

docker build -t rusa .
docker run --rm rusa --help

For real processing, mount a directory with your media files:

docker run --rm -v $(pwd):/data rusa movie.mkv

Built-in TTS engines

Engine	Online	Typical quality	Notes
edge	yes	good	default engine
piper	no	good	local neural TTS
rhvoice	no	average	local voices
espeak	no	basic	very fast
gtts	yes	good	simple cloud TTS
festival	no	basic	legacy local TTS

You can also use any custom engine with --tts-cmd.

More details:

• doc/TTS_ENGINES.md
• doc/LANGUAGE_RECOMMENDATIONS.md

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Output modes

Mode	Result
default	video + original audio + voiceover
--audio-only	audio file only
--subs-mode auto	try copy, then convert, then drop subtitles if needed
--subs-mode copy	keep subtitles as-is or fail
--subs-mode convert	convert subtitles to a compatible text format
--subs-mode drop	write output without subtitles

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Cache

rusa uses two caches:

• TTS cache: generated speech files
• WAV cache: converted WAV files after speed change and silence trim

Defaults:

• cache root: ~/.cache/rusa
• max size: 2 GiB

Environment variables:

Variable	Meaning	Default
RUSA_CACHE_DIR	Cache root directory	~/.cache/rusa
RUSA_CACHE_MAX_SIZE	Max cache size in bytes	2147483648

Commands:

rusa --cache-stats
rusa --cache-clear
rusa --no-cache movie.mkv

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Exit codes

Code	Meaning
0	success
1	runtime error
2	usage error
3	missing dependency
4	subtitle error
5	codec / encoder error

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Tests

# Offline tests
pytest -q -m 'not slow and not live_tts'

# Fast CLI smoke tests
pytest -q tests/test_cli_smoke.py

# Live tests (network access required for edge-tts)
pytest -q -m 'live_tts and not slow'

# Full suite
pytest -q

# Force local fixture generation (requires ffmpeg)
pytest -q --generate-fixtures

If generated fixtures are missing and ffmpeg is unavailable, unit and smoke tests still run. Only fixture-dependent integration tests are affected.

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Diagnostics

Missing dependencies

If you see one of these errors:

• ffmpeg was not found in PATH
• ffprobe was not found in PATH
• edge-tts is not installed

check that:

1. ffmpeg and ffprobe are installed and available in PATH
2. edge-tts is installed in the same Python environment as rusa
3. on Windows, ffmpeg.exe is in PATH

Subtitle codec error

If you see something like:

Subtitle codec mov_text ... is not supported

then:

• --subs-mode auto will try fallback modes automatically
• --subs-mode copy fails early
• --subs-mode convert writes a compatible text subtitle format directly
• --subs-mode drop writes the file without subtitles

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Development and release docs

• doc/roadmap.md
• doc/implementation_plan.md
• CHANGELOG.md
• CONTRIBUTING.md
• RELEASE_CHECKLIST.md

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License

MIT

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README contract

This README is the behavioral contract for the project.

If code and documentation diverge, update the README together with the code change.