| # CLAUDE.md |
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| This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository. |
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| ## Project Overview |
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| LiveTrans is a real-time audio translation system for video players on Windows. It captures system audio via WASAPI loopback, runs speech recognition, and translates via LLM APIs, displaying results in a transparent overlay. |
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| **Current phase**: Phase 0 Python prototype (Phase 1 will be a C++ DirectShow Audio Tap Filter). |
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| ## Running |
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| ```bash |
| # Must use the project venv (system Python lacks dependencies) |
| .venv/Scripts/python.exe main.py |
| ``` |
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| Linter: `ruff` (installed globally). Run `python -m ruff check --select F,E,W --ignore E501,E402 *.py` to lint. E402 is intentionally ignored because `main.py` requires torch before PyQt6. |
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| ## Architecture |
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| The pipeline runs in a background thread: **Audio Capture (32ms chunks) -> VAD -> ASR -> Translation (async) -> Overlay** |
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| ``` |
| main.py (LiveTransApp) |
| |-- model_manager.py Centralized model detection, download, cache utils |
| |-- audio_capture.py WASAPI loopback via pyaudiowpatch, auto-reconnects on device change |
| |-- vad_processor.py Silero VAD / energy-based / disabled modes, progressive silence + backtrack split |
| |-- asr_engine.py faster-whisper (Whisper) backend |
| |-- asr_sensevoice.py FunASR SenseVoice backend (better for Japanese) |
| |-- asr_funasr_nano.py FunASR Nano backend |
| |-- translator.py OpenAI-compatible API client, streaming, make_openai_client() |
| |-- subtitle_overlay.py PyQt6 transparent overlay (2-row header: controls + model/lang combos) |
| |-- control_panel.py Settings UI (5 tabs: VAD/ASR, Translation, Style, Benchmark, Cache) |
| |-- dialogs.py Setup wizard, model download/load dialogs, ModelEditDialog |
| |-- benchmark.py Translation benchmark (BENCH_SENTENCES, run_benchmark()) |
| |-- log_window.py Real-time log viewer |
| ``` |
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| ### Threading Model |
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| - **Main thread**: Qt event loop (all UI) |
| - **Pipeline thread**: `_pipeline_loop` in `LiveTransApp` - reads audio, runs VAD/ASR/translation |
| - **ASR loading**: Background thread via `_switch_asr_engine` (heavy model load, ~3-8s) |
| - Cross-thread UI updates use **Qt signals** (e.g., `add_message_signal`, `update_translation_signal`) |
| - ASR readiness tracked by `_asr_ready` flag; pipeline drops segments while loading |
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| ### Configuration |
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| - `config.yaml` - Base configuration (audio, ASR, translation, subtitle defaults) |
| - `user_settings.json` - Runtime settings persisted by control panel (models, VAD params, ASR engine choice, optional `cache_path`). Takes priority over config.yaml on load. |
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| ### Model Config |
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| Each model in `user_settings.json` has: `name`, `api_base`, `api_key`, `model`, `proxy` ("none"/"system"/custom URL), optional `no_system_role` (bool, for APIs that reject system messages like Qwen-MT). |
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| Proxy handling: `proxy="none"` uses `httpx.Client(trust_env=False)` to bypass system proxy; `proxy="system"` uses default httpx behavior (env vars). |
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| ### Overlay UI (subtitle_overlay.py) |
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| DragHandle is a 2-row header bar: |
| - **Row 1**: Draggable title + action buttons (Paused/Running, Clear, Settings, Monitor, Quit) |
| - **Row 2**: Checkboxes (Click-through, Top-most, Auto-scroll) + Model combo + Target Language combo |
| |
| Style system: |
| - `DEFAULT_STYLE` and `STYLE_PRESETS` defined in `subtitle_overlay.py` — 14 presets including terminal themes (Dracula, Nord, Monokai, Solarized, Gruvbox, Tokyo Night, Catppuccin, One Dark, Everforest, Kanagawa) |
| - Default style is high-contrast (pure black background, white translation text, 14pt) |
| - Original and translation text have independent `font_family` fields (`original_font_family`, `translation_font_family`) |
| - `SubtitleOverlay.apply_style(style)` updates container/header backgrounds, window opacity, and rebuilds all message HTML |
| - Style dict stored in `user_settings.json` under `"style"` key; forwarded via `settings_changed` signal → `main.py` → `overlay.apply_style()` |
| - Backward compat: old `font_family` key auto-migrated to split fields in `apply_style()` |
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| Key overlay features: |
| - **Top-most**: Toggles `WindowStaysOnTopHint`; requires `setWindowFlags()` + `show()` to take effect |
| - **Click-through**: Uses Win32 `WS_EX_TRANSPARENT` on the scroll area while keeping header interactive |
| - **Auto-scroll**: Controls whether new messages/translations auto-scroll to bottom |
| - **Model combo**: Populated from `user_settings.json` models list; switching emits `model_switch_requested` signal |
| - **Target Language combo**: Emits `target_language_changed`; synced from settings on startup |
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| ### Settings UX |
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| - **Auto-save with debounce**: All control panel settings (combos, spinboxes) auto-save after 300ms debounce via `_auto_save()` → `_do_auto_save()`. No manual Save button needed. |
| - **Slider special handling**: VAD/Energy sliders update labels in real-time but only trigger save on `sliderReleased` (mouse) or immediately for keyboard input (`isSliderDown()` check). |
| - **Apply Prompt button**: Kept because TextEdit shouldn't trigger on every keystroke. Also persists to disk. |
| - **Cache path**: Default `./models/` (not `~/.cache`). Applied at startup in `main.py` before `import torch` via `model_manager.apply_cache_env()`. |
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| ### Startup Flow |
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| 1. `main.py` reads `user_settings.json` and calls `apply_cache_env()` before `import torch` |
| 2. First launch (no `user_settings.json`) → `SetupWizardDialog`: choose hub + path + download Silero+SenseVoice |
| 3. Non-first launch but models missing → `ModelDownloadDialog`: auto-download missing models |
| 4. All models ready → create main UI (overlay, panel, pipeline) |
| 5. Runtime ASR engine switch: if uncached → `ModelDownloadDialog`, then `_ModelLoadDialog` for GPU loading |
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| ### Key Patterns |
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| - `torch` must be imported before PyQt6 to avoid DLL conflicts on Windows (PyTorch 2.9.0+ bug, see `main.py` and [pytorch#166628](https://github.com/pytorch/pytorch/issues/166628)) |
| - Cache env vars set at module level in `main.py` before `import torch` to ensure `TORCH_HOME` is respected |
| - Deferred initialization: ASR model loading and settings application happen via `QTimer.singleShot(100)` after UI is shown to prevent startup freeze |
| - `make_openai_client()` in `translator.py` is the single shared function for proxy-aware OpenAI client creation (used by both translator and benchmark) |
| - `create_app_icon()` in `main.py` generates the app icon; set globally via `app.setWindowIcon()` so all windows inherit it |
| - Model cache detection (`is_asr_cached`, `get_local_model_path`) checks both ModelScope and HuggingFace paths to avoid redundant downloads when switching hubs |
| - Settings log output (`_apply_settings`) filters out `models` and `system_prompt` to avoid leaking API keys |
| - FunASR Nano: `asr_funasr_nano.py` does `os.chdir(model_dir)` before `AutoModel()` so relative paths in config.yaml (e.g. `Qwen3-0.6B`) resolve locally instead of triggering HuggingFace Hub network requests |
| - `Translator` defaults to 10s timeout via `make_openai_client()` to prevent API calls from hanging indefinitely |
| - Log window is created at startup but hidden; shown via tray menu "Show Log" |
| - Audio chunk duration is 32ms (512 samples at 16kHz), matching Silero VAD's native window size for minimal latency |
| - VAD adaptive silence mode: tracks recent pause durations, sets silence threshold to P75 × 1.2, auto-adjusts between 0.3s~2.0s |
| - VAD progressive silence: buffer越长接受越短的停顿切分 (<3s=full, 3-6s=half, 6-10s=quarter of silence_limit) |
| - VAD backtrack split: max duration时回溯confidence history找最低谷切分，remainder保留到下一段；三级策略（绝对低谷→相对低谷20%→低于均值兜底） |
| - FunASR `disable_pbar=True` required in all `generate()` calls — tqdm crashes in GUI process when flushing stderr |
| - ASR engine lifecycle: each engine exposes `unload()` (move to CPU + release) and `to_device(device)` (in-place migration). Device switching uses `to_device()` for PyTorch engines (SenseVoice/FunASR) and full reload for ctranslate2 (Whisper). Release order: `unload()` → `del` → `gc.collect()` → `torch.cuda.empty_cache()` |
| - Whisper (ctranslate2) only accepts `device="cuda"` not `"cuda:0"`; device index passed via `device_index` param. Parsed from combo text like `"cuda:0 (RTX 4090)"` in `_switch_asr_engine` |
| - VAD speech density filter: `_flush_segment()` discards segments where <25% of chunks are above confidence threshold (noise rejection) |
| - ASR text density filter: segments ≥2s producing ≤3 alnum characters are discarded as noise |
| - Settings file uses atomic write (write to `.tmp` then `os.replace`) to prevent corruption on crash |
| - `stop()` joins pipeline thread before flushing VAD to prevent concurrent `_process_segment` calls |
| - Cancelled ASR download/failed load restores `_asr_ready` if old engine is still available |
| - `Translator._build_system_prompt` catches format errors in user prompt templates, falls back to DEFAULT_PROMPT |
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| ## Language & Style |
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| - Respond in Chinese |
| - Code comments in English only where critical |
| - Commit messages without Co-Authored-By |
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