srtspeak

Multilingual SRT TTS. Forces each cue into its exact start/end window (xAI Grok TTS + ffmpeg).

Also includes SRT→SRT translation (translate) and glossary suggestion (glossary-suggest) via Grok Chat (same XAI_API_KEY).

Authoritative design: DESIGN.md (implementation-aligned).
Translate design: docs/SRT_TRANSLATE_DESIGN.md.

Languages: English | 日本語

Requirements

Item	Detail
OS	Windows / macOS / Linux (developed and verified on Windows)
Python	3.11+
ffmpeg / ffprobe	Prefer on PATH; optional fallback via imageio-ffmpeg
API key	XAI_API_KEY only for real TTS / translate / glossary / ja_yomi (not needed for dry-run without Chat)

Package version: 0.1.5 (pyproject.toml).

Install

From PyPI:

python -m pip install srtspeak

Optional ffmpeg fallback via pip:

python -m pip install "srtspeak[ffmpeg]"

Core install already includes PySide6 (GUI) and keyring (OS credential store).

After install, the srtspeak command is available:

srtspeak --help
srtspeak doctor

From source (development)

Clone the repository, then editable install from the repo root:

git clone https://github.com/awaku7/srtspeak.git
cd srtspeak
python -m pip install -e ".[ffmpeg,dev]"

Dev extras ([dev]): pytest / ruff / Babel / keyring.

Without install (repo checkout only):

set PYTHONPATH=src
python -m srtspeak --help

There is no [ja] extra. Japanese kanji→hiragana preprocess (ja_yomi) uses the Grok Chat API with the same XAI_API_KEY (default on for lang=ja).

Launch

After pip install (PyPI or editable), use the srtspeak entry point:

srtspeak gui
srtspeak doctor
srtspeak --help
srtspeak dry-run --srt GRAN_TENKU_japan.srt --lang ja

python -m srtspeak gui

When ffmpeg is missing

Resolution order (core/ffmpeg_resolve.py):

1. ffmpeg / ffprobe on PATH (shutil.which)
2. Optional dependency imageio-ffmpeg bundled binary (get_ffmpeg_exe())
3. Otherwise FFmpegNotFoundError

Situation	Behavior
srtspeak doctor	Prints ffmpeg: MISSING (...). Exit code 0 (diagnostics only)
dry-run (build)	ffmpeg not required (parse + char count + cost estimate only)
Real build / build-all	Fails at fit stage. CLI exit code 2
translate / glossary-suggest	ffmpeg not required
imageio-ffmpeg only	Works, but ffprobe may be (none). Full PATH ffmpeg is recommended

Install examples (Windows)

WinGet (recommended):

winget install Gyan.FFmpeg

Then in a new terminal:

ffmpeg -version
ffprobe -version
srtspeak doctor

If you prefer not to change PATH:

python -m pip install "srtspeak[ffmpeg]"
srtspeak doctor

doctor shows source: path for system ffmpeg, or source: imageio_ffmpeg for the pip bundle.

xAI (Grok TTS / Chat) signup and API key

TTS is xAI Grok only (POST https://api.x.ai/v1/tts).
Japanese yomi, SRT translate, and glossary-suggest use Grok Chat (/v1/chat/completions). Create the key in the console.

1. Account

1. Open https://console.x.ai/
2. Sign up / log in (xAI account)
3. Accept terms and set up billing / credits as guided
   • TTS is usage-based. dry-run estimate uses $15 / 1M characters (implementation unit price)
   • ja_yomi / translate / glossary Chat calls are additional usage when enabled

2. Create an API key

1. Open API Keys (or equivalent) in the console
2. Create a new key
3. Copy the value (often starts with xai-)
   • It may not be shown again — put it in an env var immediately
4. Do not put the key in chat, Git, report.json, or screenshots

Official docs:

• Text to Speech
• Voice
• API: https://api.x.ai/v1/tts / voices: https://api.x.ai/v1/tts/voices

3. How this tool reads the key

Rule	Detail
Variable	XAI_API_KEY only
CLI flag	No --api-key (avoids shell history)
Persistence	No .env; never written to report/logs/gui_settings.json
Resolve order	env → session → OS keyring → legacy Windows DPAPI (migrate) → CLI getpass / GUI mask
dry-run	Key optional (Chat APIs skipped if missing)
Real TTS / translate / glossary	resolve chain; missing → exit code 2
GUI	Save on this PC / Clear saved via keyring (core dependency)

Windows cmd (current window only):

set "XAI_API_KEY=xai-..."
srtspeak doctor

PowerShell:

$env:XAI_API_KEY = "xai-..."
srtspeak doctor

Persist for new terminals (cmd):

setx XAI_API_KEY "xai-..."

doctor shows presence only (source label):

XAI_API_KEY: set (env)

XAI_API_KEY: set (keyring)

XAI_API_KEY: set (dpapi)

or:

XAI_API_KEY: missing

Invalid key / insufficient balance surfaces as TTS error: ... / translate error: ... during run (exit code 1).

Commands

srtspeak --help
srtspeak doctor
srtspeak languages
srtspeak voices
srtspeak gui
srtspeak build --help
srtspeak build-all --help
srtspeak dry-run --help
srtspeak translate --help
srtspeak glossary-suggest --help

Command	Purpose
doctor	Check XAI_API_KEY, ffmpeg/ffprobe, ja_yomi, translate, glossary-suggest, PySide6
languages	Language codes sendable to the API
voices	Grok voices (API if key present, else builtin; male + female)
dry-run	Parse + char count + TTS cost estimate (no ffmpeg)
build	Generate one language (TTS)
build-all	Generate multiple languages in sequence
translate	SRT→SRT multi-target translation (Grok Chat; timing-locked)
glossary-suggest	Propose glossary JSON from source SRT via Grok Chat
gui	PySide6 GUI (Build + Translate tabs)

Global options:

--locale en|ja     UI locale (default: SRTSPEAK_LOCALE → LC_ALL/LANG → system → en)
--verbose / --quiet

Place --quiet / --verbose before the subcommand:

srtspeak --locale ja doctor
srtspeak --verbose build --srt sample.srt --lang ja --dry-run

Input / output layout

TTS build

--out is the output root. Artifacts always go under {out}/{lang}/.

out/{lang}/
  cues/                  per-cue audio (normalized)
  fitted/                duration-fitted audio
  {stem}_{lang}.wav          # stem = input SRT filename (without ext)
  {stem}_{lang}.mp3          # if --also-mp3
  report.json
out/work/{lang}/
  raw/
  cache/
  ja_yomi_cache.json     when ja + ja_yomi

• Default root: out → e.g. out/ja/
• --out out/en with --lang en → out/en/ (no double nesting)
• --out artifacts with --lang pt → artifacts/pt/
• build-all writes summary.json at the out root

Translate

--out default: out/srt_gen. Work cache under out/work/translate/by_out/ (keyed by output SRT file name).

out/srt_gen/
  translate_report.json
  {target}/                         # BCP-47 token (e.g. en, pt-BR)
    {source_stem}_{target}.srt      # naming=stem (default)
    GRAN_TENKU_{target}.srt         # naming=gran_tenku
out/work/translate/by_out/
  {target}__{out_srt_name}.json   # e.g. en__GRAN_TENKU_en.srt.json

Usage

Environment check

srtspeak doctor

Before a real build you typically want:

• XAI_API_KEY: set (env)
• ffmpeg: path with source: path (or imageio_ffmpeg)
• ja_yomi: grok-chat (Grok Chat API)
• translate: grok-chat (same XAI_API_KEY)
• glossary-suggest: grok-chat (same XAI_API_KEY)

Cost estimate (no ffmpeg)

srtspeak dry-run --srt GRAN_TENKU_japan.srt --lang ja

Single-language build

set "XAI_API_KEY=xai-..."

srtspeak build --srt GRAN_TENKU_japan.srt --lang ja --voice-id leo
srtspeak build --srt GRAN_TENKU_English.srt --lang en --voice-id leo --out out
srtspeak build --srt GRAN_TENKU_Portugus.srt --lang pt --voice-id leo

Main options:

Option	Meaning	Default
--srt	Input SRT	required
--lang	Internal key ja / en / pt …	may be guessed from filename
--language-code	BCP-47 sent to API	lang default (pt→pt-BR)
--out	Output root (lang appended)	out
--work-dir	Work root	out/work
--voice-id	Voice ID (or lang=id for build-all)	leo
--short-mode	pad / stretch	pad
--max-speed	Cap on atempo product; over → hard_trim	none
--tail-pad-ms	Silence after last cue end (no base_wav)	0
--base-wav	Mix narration onto this WAV (keeps base rate/ch)	none
--ja-yomi / --no-ja-yomi	JA kanji→hiragana via Grok Chat	on
--strip-emoticons / --no-strip-emoticons	Strip kaomoji for TTS only; emoji kept; SRT unchanged	on
--no-cache	Ignore existing TTS/ja_yomi caches (still write after success)	off
--limit N	First N cues only	all
--dry-run	Estimate only	off
--also-mp3	Also write mp3 of final track	off
--jobs	Parallelism (MVP: 1 only)	1

Smoke a few cues:

srtspeak build --srt GRAN_TENKU_japan.srt --lang ja --limit 3 --voice-id leo

Portuguese as pt-PT:

srtspeak build --srt GRAN_TENKU_Portugus.srt --lang pt --language-code pt-PT --voice-id leo

Mix onto an existing bed:

srtspeak build --srt GRAN_TENKU_japan.srt --lang ja --base-wav bed.wav --voice-id leo

Disable Japanese yomi:

srtspeak build --srt GRAN_TENKU_japan.srt --lang ja --no-ja-yomi --voice-id leo

Force fresh TTS (ignore caches):

srtspeak build --srt GRAN_TENKU_japan.srt --lang ja --no-cache --voice-id leo

Multi-language batch

srtspeak build-all ^
  --map ja=GRAN_TENKU_japan.srt ^
  --map en=GRAN_TENKU_English.srt ^
  --map pt=GRAN_TENKU_Portugus.srt ^
  --voice-id leo ^
  --out out

Per-language voices:

srtspeak build-all ^
  --map ja=GRAN_TENKU_japan.srt ^
  --map en=GRAN_TENKU_English.srt ^
  --voice-id ja=leo --voice-id en=orion

Translate (SRT→SRT)

Timing-locked multi-target translation. Cue count / index / start-end ms stay identical; only text changes. Provider: Grok Chat structured JSON (grok-4.5 default). Separate from the TTS pipeline.

set "XAI_API_KEY=xai-..."

srtspeak translate ^
  --srt GRAN_TENKU_japan.srt ^
  --source-lang ja ^
  --to en --to pt-BR --to es ^
  --out out/srt_gen ^
  --glossary glossary.json ^
  --length-mode hint

Option	Meaning	Default
--srt	Source SRT	required
--source-lang	Source language	filename guess / ja
--to	Target BCP-47 (repeat or comma-separated)	required (≥1)
--out	Output root	out/srt_gen
--work-dir	Work root	out/work
--glossary	Glossary JSON path	none
--length-mode	off / hint / enforce / report-only	hint
--on-empty	fail / keep-source	fail
--batch-size	Cues per Chat batch	8
--model	Grok Chat model id	grok-4.5
--limit N	First N cues only	all
--dry-run	Estimate only (no Chat)	off
--fail-fast	Stop on first target error	off
--no-cache	Ignore existing translate caches (still write)	off
--naming	stem → {source_stem}_{lang}.srt / gran_tenku → GRAN_TENKU_{lang}.srt	stem

Dry-run:

srtspeak translate --srt GRAN_TENKU_japan.srt --to en,pt-BR --dry-run

Then TTS the generated SRT:

srtspeak build-all ^
  --map ja=GRAN_TENKU_japan.srt ^
  --map en=out/srt_gen/en/GRAN_TENKU_japan_en.srt ^
  --voice-id leo --out out

(With --naming gran_tenku, paths become out/srt_gen/en/GRAN_TENKU_en.srt.)

Glossary suggest

srtspeak glossary-suggest ^
  --srt GRAN_TENKU_japan.srt ^
  --source-lang ja ^
  --to en --to pt-BR ^
  --out glossary.json

Option	Meaning	Default
--srt	Source SRT	required
--source-lang	Source language	filename guess / ja
--to	Target BCP-47 (repeat or comma-separated)	required
--out	Output glossary JSON	glossary.json
--merge	Merge into existing glossary (existing wins on conflict)	none
--force	Overwrite --out without merge	off
--min-count	Min local term frequency for candidates	2
--model	Grok Chat model id	grok-4.5
--limit N	First N cues only	all

If --out already exists and --force is not set, new suggestions are merged with existing terms (existing preferred).

GUI

srtspeak gui

• Tabs: Build (TTS) and Translate
• Build: SRT, language (BCP-47 + Detect), voice, absolute output folder + directory picker, base WAV, max cues, dry-run, ja_yomi, strip kaomoji, no-cache
• Translate: source SRT, source lang, multi-target checkboxes, absolute output folder + directory picker, glossary path + Suggest, length mode, batch size, naming (stem / gran_tenku), fail-fast, no-cache, dry-run
• Shared: API key (masked) + status/placeholder showing load source (env / keyring / DPAPI / session) + Save on this PC / Clear saved
• Key input: whitespace/newlines stripped (normalize_api_key); language detect uses the same resolve chain as build/translate
• Completion: non-modal result dialog; main window stays open
• Browse / path confirm: filename → source language guess (guess_lang_from_filename)
• Progress: bottom status + bar (0–1000); worker → thread-safe queue + ~80ms drain; Cancel via CancellationToken
• Optional diag: SRTSPEAK_GUI_PROGRESS_LOG=1 → out/work/gui_progress.log only
• Non-secret settings in gui_settings.json (never the key plaintext)
• UTF-8 defaults: CLI/GUI set PYTHONUTF8=1 and PYTHONIOENCODING=utf-8 when unset

Processing notes

TTS build

• Pipeline: parse → limit → ja_yomi (ja) → TTS/cache → normalize → fit → timeline → report
• TTS: xAI Grok unary REST only (speed always 1.0)
• ja_yomi: Grok Chat structured JSON, batch 5, cache under out/work/{lang}/
• strip_emoticons: kaomoji stripped for TTS speak text only; emoji kept; stored SRT cues unchanged; default on
• Fit: ffmpeg CLI only (atempo 0.5–2.0 multi-stage; short cues default to pad)
• Timeline: silence canvas or base_wav; place in half-open [start, end); PCM add-mix (clip ±32767)
• Track length: last cue end + tail_pad_ms, or base_wav length when --base-wav is set
• Audio (no base): mono s16le 24 kHz WAV; with base: base native rate/channels preserved
• Cost estimate (dry-run): $15 / 1M chars (TTS text; Chat yomi not included in that figure)
• Voices: builtin catalog includes male and female; default leo
• --no-cache: skip reading TTS/ja_yomi caches; still write after success

Translate

• Pipeline: parse → limit → per target: cache → Chat batches → structure lock → write SRT → translate_report.json
• Structure lock: cue count / index / start_ms / end_ms identical to source
• Glossary optional (terms / do_not_translate / tone)
• length_mode hint (default) injects budget into prompt; enforce may run a 2nd compress pass
• Model default grok-4.5; batch_size default 8

Exit codes

Code	Meaning
0	Success (doctor is 0 even if ffmpeg is missing)
1	Runtime errors (e.g. TTS / translate / glossary)
2	Config/args/invalid SRT/ffmpeg missing/key missing
130	Cancelled (Ctrl+C)

Development

git clone https://github.com/awaku7/srtspeak.git
cd srtspeak
python -m pip install -e ".[dev,ffmpeg]"
set PYTHONPATH=src
python -m pytest -q
python -m ruff check src tests
python -m ruff format src tests

i18n (when messages change):

python scripts/update_i18n.py

Sample inputs (expected alongside the repo)

File	lang	Notes
GRAN_TENKU_japan.srt	ja	ja_yomi default on
GRAN_TENKU_English.srt	en
GRAN_TENKU_Portugus.srt	pt	API default pt-BR if unspecified

Timecodes are assumed aligned across the three files (design-time: 293 cues, 00:00:07,600–00:12:44,000).

License

Apache License 2.0 (see LICENSE)

Author

Hirofumi Ukawa hirofumi@ukawa.biz