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# Phase 4: System Audio Capture → ASR → RAG — Implementation Plan
# Phase 4: System Audio & Mic Capture → ASR → RAG — Implementation Plan
**Created:** 2026-05-09
**Updated:** 2026-05-09
**Updated:** 2026-05-14
**Status:** 📋 Draft (Not Started)
**Depends on:** Phase 1 (Complete), Phase 2 (Complete), Phase 3 (Complete)
@ -9,24 +9,40 @@
## 1. Overview
Phase 4 adds **system audio capture** as a third audio source in the LTTPage, alongside file Upload and YouTube. Instead of playing a video in the browser, the user captures audio output from any application on their computer (browser tab, Spotify, Zoom, system sounds) and pipes it through the existing ASR → RAG pipeline.
Phase 4 adds two new live audio sources in the LTTPage, alongside file Upload:
**Use cases:**
1. **System Audio Capture** — captures audio output from any application on the user's computer (browser tab, Spotify, Zoom, system sounds) via `getDisplayMedia()`.
2. **Listen Mic** — captures microphone input (user's voice, room audio) via `getUserMedia({ audio: true })`.
Both pipe audio through the existing WebSocket → DashScope realtime ASR → RAG pipeline.
### System Audio — Use Cases
- Watching a YouTube video in a regular browser tab (no proxy needed — just share that tab's audio)
- Listening to a podcast, lecture, or meeting and getting real-time transcript + RAG
- Transcribing any audio playing on the computer without needing to download files
### How It Works
### Listen Mic — Use Cases
- Recording a live meeting or lecture through the computer's microphone
- Dictating questions or notes verbally and getting RAG answers
- Transcribing spoken Cantonese in real time without a video source
### How They Work
```
User clicks "System Audio" → clicks "Start Capture"
→ Browser shows permission dialog (screen/tab picker)
→ User selects tab/window/screen (with audio)
→ getDisplayMedia() returns MediaStream (with audio track)
→ AudioContext.createMediaStreamSource(stream)
→ ScriptProcessorNode (Float32 PCM, mono 16kHz)
→ WebSocket → FastAPI → DashScope realtime ASR
→ transcript → QueryInput → RAG Pipeline
[System Audio]
User clicks "System Audio" → "Start Capture"
→ Browser shows permission dialog (screen/tab picker)
→ User selects tab/window/screen (with audio)
→ getDisplayMedia() returns MediaStream (with audio track)
→ AudioContext.createMediaStreamSource(stream)
→ ScriptProcessorNode → WebSocket → DashScope ASR → Transcript → RAG
[Listen Mic]
User clicks "Listen Mic" → "Start Listening"
→ Browser shows microphone permission prompt
→ getUserMedia({ audio: true }) returns MediaStream
→ AudioContext.createMediaStreamSource(stream)
→ ScriptProcessorNode → WebSocket → DashScope ASR → Transcript → RAG
```
### Audio Routing (vs Existing Sources)
@ -34,59 +50,85 @@ User clicks "System Audio" → clicks "Start Capture"
| Source | Audio Input | SourceNode Type | Start/Stop Trigger |
|--------|-------------|-----------------|-------------------|
| Upload | `<video>` element | `createMediaElementSource` | play/pause events |
| YouTube | `<audio>` element | `createMediaElementSource` | play/pause events on `<video>` |
| **System Audio** | MediaStream from `getDisplayMedia()` | `createMediaStreamSource` | Manual Start/Stop button + track ended event |
| **Listen Mic** | MediaStream from `getUserMedia({ audio: true })` | `createMediaStreamSource` | Manual Start/Stop button + track ended event |
### Why New Hook (Not Reuse Existing)
### Why New Hooks (Not Reuse Existing)
The existing `useVideoASR` and `useYouTubeASR` hooks depend on HTML media elements (`<video>`, `<audio>`) for both the audio source and play/pause lifecycle. System audio capture uses a **MediaStream** object (no DOM element), and its lifecycle is controlled by user permission (grant/revoke) and manual start/stop, not DOM events. A new hook is architecturally cleaner than overloading the existing ones with branching logic.
The existing `useVideoASR` hook depends on HTML media elements (`<video>`) for both the audio source and play/pause lifecycle. Both new sources use **MediaStream** objects (no DOM element), and their lifecycle is controlled by user permission (grant/revoke) and manual start/stop, not DOM events.
**System Audio** and **Listen Mic** share the same audio processing pipeline (`MediaStream → AudioContext → ScriptProcessorNode → WebSocket`) but differ in their capture API. A shared internal audio processing utility (`useMediaStreamASR` or similar) should be extracted to avoid code duplication between the two hooks.
---
## 2. User Flow
1. User selects **"System Audio"** tab (third option alongside Upload / YouTube)
### 2.1 System Audio
1. User selects **"System Audio"** tab (second option alongside Upload / Listen Mic)
2. UI shows a **"Start Capture"** button with browser compatibility info
3. User clicks **"Start Capture"**
4. Browser opens **permission dialog** (screen/tab picker)
- User selects a browser tab (e.g., "YouTube — Live Stream") or "Entire Screen"
- User checks "Share audio" if available
5. On approval: capture starts — status indicator shows "Capturing" with a live audio level meter
6. Real-time ASR transcription flows into **QueryInput** (same as Upload/YouTube)
6. Real-time ASR transcription flows into **QueryInput** (same as Upload)
7. User can **edit transcript while capturing** continues
8. User clicks **"Stop Capture"** to end — transcript stays in QueryInput
9. User submits query → RAG pipeline processes it
10. **"Full Transcript" button hidden** (streaming ASR only, same as YouTube)
10. **"Full Transcript" button hidden** (streaming ASR only — no batch transcription for live sources)
### Permission Denied Flow
#### Permission Denied Flow
- User clicks "Cancel" in permission dialog → error: "Permission denied — system audio capture requires your explicit permission"
- User revokes permission (Chrome "Stop sharing") → capture stops gracefully, status: "Capture stopped"
- No audio track in the stream → error: "No audio track found in the shared content"
1. If user clicks "Cancel" in permission dialog → error state: "Permission denied — system audio capture requires your explicit permission"
2. If user revokes permission (Chrome "Stop sharing") → capture stops gracefully, status: "Capture stopped"
3. If no audio track in the stream → error: "No audio track found in the shared content"
### 2.2 Listen Mic
1. User selects **"Listen Mic"** tab (third option)
2. UI shows a **"Start Listening"** button (no browser compatibility warning — widely supported)
3. User clicks **"Start Listening"**
4. Browser shows **microphone permission prompt** (first time only)
5. On approval: listening starts — status indicator shows "Listening" with a live audio level meter
6. Real-time ASR transcription flows into **QueryInput**
7. User can **edit transcript while listening** continues
8. User clicks **"Stop Listening"** to end — transcript stays in QueryInput
9. User submits query → RAG pipeline processes it
10. **"Full Transcript" button hidden** (streaming ASR only)
#### Permission Denied Flow
- User clicks "Block" in mic permission prompt → error: "Microphone access denied — please allow microphone access in your browser settings"
- User revokes permission via browser UI → listening stops, status: "Microphone disconnected"
- No audio track → error: "No microphone input detected"
---
## 3. Architecture
### 3.1 Component Tree (LTTPage — System Audio Mode)
### 3.1 Component Tree (LTTPage — All Sources)
```
LTTPage
├── SourceSelector (tabs: Upload | YouTube | System Audio)
├── SourceSelector (tabs: Upload | System Audio | Listen Mic)
├── [source === 'system-audio']
│ ├── SystemAudioCapture
│ │ ├── Start/Stop button
│ │ ├── Status indicator (idle | requesting | capturing | error)
│ │ ├── Audio level meter (optional, nice-to-have)
│ │ └── Browser compatibility note (non-Chrome users)
│ └── (no video player — audio-only capture)
├── QueryInput (receives transcript from useSystemAudioASR)
│ └── SystemAudioCapture
│ ├── Start/Stop button
│ ├── Status indicator (idle | requesting | capturing | error)
│ ├── Audio level meter (optional, nice-to-have)
│ └── Browser compatibility note (non-Chrome users)
├── [source === 'mic']
│ └── MicCapture
│ ├── Start/Stop button
│ ├── Status indicator (idle | requesting | listening | error)
│ └── Audio level meter (optional, nice-to-have)
├── QueryInput (receives transcript from active ASR hook)
├── ExtractedQuestionsDisplay
└── RAG Response Panel
```
### 3.2 Data Flow
#### System Audio
```
SystemAudioCapture (UI)
@ -99,32 +141,51 @@ useSystemAudioASR hook
│ └── User picks tab/window → returns MediaStream
├── AudioContext.createMediaStreamSource(stream)
│ └── MediaStreamAudioSourceNode
├── ScriptProcessorNode (4096 buffer, mono 16kHz)
│ └── onaudioprocess: convert Float32 → Int16 PCM
├── WebSocket → ws://host/ws/asr/{uuid}?language=yue
│ └── Sends binary PCM frames
└── Returns: { status, transcript, partialTranscript, startCapture, stopCapture }
LTTPage unifies: const asr = source === 'system-audio' ? systemAudioASR : ...
```
#### Listen Mic
```
MicCapture (UI)
├── "Start Listening" click → calls startListening() from hook
QueryInput receives asr.partialTranscript
useMicASR hook
├── getUserMedia({ audio: true })
│ └── Browser shows mic permission prompt → returns MediaStream
├── AudioContext.createMediaStreamSource(stream)
├── ScriptProcessorNode (4096 buffer, mono 16kHz)
├── WebSocket → ws://host/ws/asr/{uuid}?language=yue
└── Returns: { status, transcript, partialTranscript, startListening, stopListening }
```
#### LTTPage Unification
```typescript
const asr = source === 'system-audio' ? systemAudioASR
: source === 'mic' ? micASR
: uploadASR
```
### 3.3 Backend Changes
**Minimal.** The existing WebSocket ASR endpoint (`ws_asr.py`) already accepts audio from any source. The only addition is handling a **UUID-based `video_id`** for system audio sessions (no real video file).
**Minimal.** The existing WebSocket ASR endpoint (`ws_asr.py`) already accepts audio from any source. The only additions are UUID-based `video_id` handling and feature toggles.
| Change | File | Description |
|--------|------|-------------|
| Allow UUID video_id | `backend/app/routers/ws_asr.py` | Accept non-file-based video IDs (already accepts any string) |
| Transcript persistence | `backend/app/services/history_service.py` | Store system audio transcripts with UUID session ID (optional — nice-to-have) |
| Config | `backend/app/core/config.py` | Add `SYSTEM_AUDIO_ENABLED` toggle (default: true) |
| Transcript persistence | `backend/app/services/history_service.py` | Store system audio & mic transcripts with UUID session ID (optional — nice-to-have) |
| Config | `backend/app/core/config.py` | Add `SYSTEM_AUDIO_ENABLED` and `MIC_ENABLED` toggles (default: true) |
**No changes needed to:**
- DashScope ASR client (receives PCM, doesn't care about source)
@ -135,11 +196,13 @@ QueryInput receives asr.partialTranscript
| File | Status | Description |
|------|--------|-------------|
| `frontend/src/components/SourceSelector.tsx` | **New** | Reusable tab bar component (Upload \| System Audio \| Listen Mic) |
| `frontend/src/hooks/useSystemAudioASR.ts` | **New** | Hook: getDisplayMedia → AudioContext → WebSocket |
| `frontend/src/components/SystemAudioCapture.tsx` | **New** | UI: Start/Stop button, status, compatibility note |
| `frontend/src/pages/LTTPage.tsx` | **Modified** | Add "System Audio" tab, wire hook, unify ASR |
| `frontend/src/types/index.ts` | **Modified** | Add SystemAudioStatus type |
| `frontend/src/components/SourceSelector.tsx` | **Refactor** | Extract source tabs into reusable component (optional — can inline in LTTPage) |
| `frontend/src/hooks/useMicASR.ts` | **New** | Hook: getUserMedia → AudioContext → WebSocket |
| `frontend/src/components/SystemAudioCapture.tsx` | **New** | UI: Start/Stop, status, compatibility note |
| `frontend/src/components/MicCapture.tsx` | **New** | UI: Start/Stop, status |
| `frontend/src/pages/LTTPage.tsx` | **Modified** | Add source selector, wire hooks, unify ASR, conditional rendering |
| `frontend/src/types/index.ts` | **Modified** | Add SourceType, SystemAudioStatus, MicStatus types |
---
@ -150,25 +213,31 @@ QueryInput receives asr.partialTranscript
| 4.1 | Config & Infrastructure | 0.5 day | — | 📋 Draft |
| 4.2 | System Audio Capture Hook (`useSystemAudioASR`) | 1 day | 4.1 | 📋 Draft |
| 4.3 | SystemAudioCapture UI Component | 0.5 day | 4.2 | 📋 Draft |
| 4.4 | LTTPage Integration | 0.5 day | 4.2, 4.3 | 📋 Draft |
| 4.5 | Backend Adjustments | 0.5 day | 4.1 | 📋 Draft |
| 4.6 | Integration & Acceptance Tests | 1 day | 4.4, 4.5 | 📋 Draft |
| 4.7 | Polish & Documentation | 0.5 day | 4.6 | 📋 Draft |
| **Total** | | **4.5 days** | | |
| 4.4 | Mic Capture Hook (`useMicASR`) | 0.5 day | 4.1 | 📋 Draft |
| 4.5 | MicCapture UI Component | 0.5 day | 4.4 | 📋 Draft |
| 4.6 | LTTPage Integration (all 3 sources) | 0.5 day | 4.2, 4.3, 4.4, 4.5 | 📋 Draft |
| 4.7 | Backend Adjustments | 0.5 day | 4.1 | 📋 Draft |
| 4.8 | Integration & Acceptance Tests | 1 day | 4.6, 4.7 | 📋 Draft |
| 4.9 | Polish & Documentation | 0.5 day | 4.8 | 📋 Draft |
| **Total** | | **5.5 days** | | |
### Phase 4.1 — Config & Infrastructure (0.5 day)
**Objective:** Add system audio feature toggle, define types, establish UUID generation.
**Objective:** Add feature toggles, define types, establish UUID generation.
**Tasks:**
1. Add `SYSTEM_AUDIO_ENABLED` to `backend/app/core/config.py` (default: `True`)
1. Add `SYSTEM_AUDIO_ENABLED` and `MIC_ENABLED` to `backend/app/core/config.py` (default: `True`)
2. Add `SystemAudioStatus` type to `frontend/src/types/index.ts`:
```typescript
type SystemAudioStatus = 'idle' | 'requesting' | 'capturing' | 'stopping' | 'error'
```
3. Add `SystemAudioASRState` interface to types
4. Add `video_id` UUID generation helper (frontend-side: `crypto.randomUUID()`)
5. Verify WebSocket ASR endpoint accepts arbitrary `video_id` strings (it does — confirm with a quick test)
3. Add `MicStatus` type:
```typescript
type MicStatus = 'idle' | 'requesting' | 'listening' | 'stopping' | 'error'
```
4. Add `SystemAudioASRState` and `MicASRState` interfaces to types
5. Add `video_id` UUID generation helper (frontend-side: `crypto.randomUUID()`)
6. Verify WebSocket ASR endpoint accepts arbitrary `video_id` strings (it does — confirm with a quick test)
**Test Files:** `backend/app/test/test_phase4_config.py`
@ -205,7 +274,7 @@ interface UseSystemAudioASRReturn {
**Pattern to Follow:**
- AudioContext setup: follow `useVideoASR.ts` lines 45-143 (AudioContext, ScriptProcessor, sample rate conversion)
- WebSocket handling: follow `useYouTubeASR.ts` lines 35-100
- WebSocket handling: follow `useVideoASR.ts` lines 35-100
- State management: combine patterns from both hooks, adapting for MediaStream source
**Test Files:** `frontend/src/test/test_phase4_useSystemAudioASR.test.ts`
@ -239,57 +308,128 @@ On Linux, only tab audio is available (not full system audio).
**Test Files:** `frontend/src/test/test_phase4_SystemAudioCapture.test.tsx`
### Phase 4.4 — LTTPage Integration (0.5 day)
### Phase 4.4 — Mic Capture Hook (0.5 day)
**Objective:** Wire the System Audio source into LTTPage, adding it as the third tab alongside Upload and YouTube.
**Objective:** Create `useMicASR.ts` hook that captures microphone input and streams it to the ASR WebSocket.
**Key Design:**
```typescript
interface UseMicASRProps {
wsUrl: string // e.g., ws://localhost:8000/ws/asr/{uuid}?language=yue
}
interface UseMicASRReturn {
status: 'idle' | 'requesting' | 'listening' | 'stopping' | 'error'
transcript: string
partialTranscript: string
error: string | null
startListening: () => Promise<void>
stopListening: () => void
}
```
**Implementation Details:**
- `startListening()`: calls `navigator.mediaDevices.getUserMedia({ audio: true, video: false })`
- On success: creates AudioContext, `createMediaStreamSource(stream)`, connects ScriptProcessor → WebSocket
- On user deny: sets status to `'idle'`, sets error "Microphone access denied"
- On no audio track: sets status to `'error'`, sets error "No microphone input detected"
- `stopListening()`: stops all tracks in the MediaStream, closes AudioContext, closes WebSocket
- Auto-stop: listens for `track.onended` (user revokes permission) → calls stopListening
- Audio processing: identical to useSystemAudioASR — `ScriptProcessorNode(4096)`, convert Float32 → Int16 PCM, send via WebSocket
- WebSocket lifecycle: connect on listening start, close on listening stop
- Cleanup: useEffect return closes AudioContext, WebSocket, and stops tracks
**Code Sharing:** Extract shared audio processing logic (`MediaStream → AudioContext → ScriptProcessorNode → WebSocket`) into a reusable internal utility (`useMediaStreamASR` or `audioPipeline.ts`) to avoid duplication between `useSystemAudioASR` and `useMicASR`.
**Test Files:** `frontend/src/test/test_phase4_useMicASR.test.ts`
### Phase 4.5 — MicCapture UI Component (0.5 day)
**Objective:** Create the `MicCapture.tsx` component with Start/Stop button and status display.
**Component Props:**
```typescript
interface MicCaptureProps {
status: MicStatus
error: string | null
onStart: () => void
onStop: () => void
}
```
**UI States:**
1. **Idle**: "Start Listening" button (blue, prominent) — no compatibility warning needed (mic is universally supported)
2. **Requesting**: "Waiting for microphone permission..." (loading spinner)
3. **Listening**: "Stop Listening" button (red) + pulsing green dot + "Listening..."
4. **Error**: Red banner with error message + "Try Again" button
**Test Files:** `frontend/src/test/test_phase4_MicCapture.test.tsx`
### Phase 4.6 — LTTPage Integration (0.5 day)
**Objective:** Create the `SourceSelector` tab bar component and wire both new sources into LTTPage.
**New Component — `SourceSelector.tsx`:**
```typescript
interface SourceSelectorProps {
activeSource: SourceType
onSelect: (source: SourceType) => void
}
```
- Three tabs: Upload (📁), System Audio (🔊), Listen Mic (🎤)
- Active tab highlighted with blue background, inactive tabs gray
- Icons from lucide-react: `Upload`, `MonitorSpeaker`, `Mic`
**Changes to `LTTPage.tsx`:**
1. Extend `SourceType` from `'upload' | 'youtube'` to `'upload' | 'youtube' | 'system-audio'`
2. Add third tab button (icon: `AudioLines` from lucide-react) in the source selector
3. Initialize `useSystemAudioASR` hook with a UUID-based WebSocket URL
4. Update `asr` variable:
1. Add `SourceType` state: `const [source, setSource] = useState<SourceType>('upload')`
2. Render `<SourceSelector activeSource={source} onSelect={setSource} />` above the panels
3. Extend `SourceType` to `'upload' | 'system-audio' | 'mic'`
4. Initialize `useSystemAudioASR` and `useMicASR` hooks with session-scoped UUIDs (generated once when tab selected, reused across Start/Stop cycles)
5. Update `asr` variable:
```typescript
const asr = source === 'youtube' ? youtubeASR
: source === 'system-audio' ? systemAudioASR
const asr = source === 'system-audio' ? systemAudioASR
: source === 'mic' ? micASR
: uploadASR
```
5. Conditional rendering:
```
{source === 'upload' && <VideoUploader />}
{source === 'youtube' && <YouTubeMode />}
6. Conditional rendering:
```tsx
{source === 'upload' && <VideoUpload />}
{source === 'system-audio' && <SystemAudioCapture />}
{source === 'mic' && <MicCapture />}
```
6. WebSocket URL: `ws://host/ws/asr/{crypto.randomUUID()}?language=yue`
7. Full Transcript button: hidden for system-audio (same as YouTube)
8. QueryInput: remains editable during capture (same behavior as other sources)
7. WebSocket URL: `ws://host/ws/asr/{sessionUUID}?language=yue` (UUID stable per session, regenerated only on source switch)
8. Full Transcript button: hidden for system-audio AND mic (streaming ASR only)
9. QueryInput: remains editable during capture/listening
**Test Files:** `frontend/src/test/test_phase4_LTTPage_integration.test.tsx`
### Phase 4.5 — Backend Adjustments (0.5 day)
### Phase 4.7 — Backend Adjustments (0.5 day)
**Objective:** Ensure backend handles system audio sessions correctly.
**Objective:** Ensure backend handles both system audio and mic sessions correctly.
**Tasks:**
1. Verify `ws_asr.py` WebSocket endpoint works with arbitrary `video_id` (UUID format) — likely no changes needed
2. Add `SYSTEM_AUDIO_ENABLED` config validation in the router (return 503 if disabled)
3. Handle system audio sessions in transcript history (optional — store with `source: 'system-audio'` metadata)
4. Verify the ASR client handles system audio PCM identically to video audio
2. Add `SYSTEM_AUDIO_ENABLED` and `MIC_ENABLED` config validation in the router (return 503 if disabled)
3. Handle system audio and mic sessions in transcript history (optional — store with `source: 'system-audio'` / `source: 'mic'` metadata)
4. Verify the ASR client handles audio from both sources identically
**No new endpoints needed.** The existing WebSocket and ASR infrastructure is source-agnostic.
**Test Files:** `backend/app/test/test_phase4_config.py`
### Phase 4.6 — Integration & Acceptance Tests (1 day)
### Phase 4.8 — Integration & Acceptance Tests (1 day)
**Objective:** Comprehensive tests for the system audio capture flow.
**Objective:** Comprehensive tests for both capture flows.
**Backend Integration Tests** (`backend/app/test/test_integration_phase4.py`):
1. WebSocket accepts UUID video_id
2. ASR processes audio from system audio session
3. Config toggle disables feature
3. ASR processes audio from mic session
4. Config toggles disable features
**Frontend Tests:**
1. **Hook tests** (`test_phase4_useSystemAudioASR.test.ts`): ~10 tests
1. **System Audio Hook tests** (`test_phase4_useSystemAudioASR.test.ts`): ~10 tests
- Mock `getDisplayMedia` → successful capture
- Mock `getDisplayMedia` → user cancels (permission denied)
- Mock `getDisplayMedia` → no audio track
@ -300,31 +440,52 @@ On Linux, only tab audio is available (not full system audio).
- `stopCapture` cleanup
- Multiple rapid start/stop cycles
2. **Component tests** (`test_phase4_SystemAudioCapture.test.tsx`): ~5 tests
2. **System Audio Component tests** (`test_phase4_SystemAudioCapture.test.tsx`): ~5 tests
- All UI states render correctly (idle, requesting, capturing, error)
- Start button calls onStart
- Stop button calls onStop
- Error state shows message and retry button
- Compatibility note visible for non-Chrome (optional)
3. **Integration tests** (`test_phase4_LTTPage_integration.test.tsx`): ~5 tests
3. **Mic Hook tests** (`test_phase4_useMicASR.test.ts`): ~8 tests
- Mock `getUserMedia` → successful capture
- Mock `getUserMedia` → user denies (permission denied)
- Mock `getUserMedia` → no audio track
- AudioContext setup and teardown
- WebSocket connection lifecycle
- `track.onended` triggers auto-stop
- `stopListening` cleanup
- PCM conversion and sending
4. **Mic Component tests** (`test_phase4_MicCapture.test.tsx`): ~4 tests
- All UI states render correctly (idle, requesting, listening, error)
- Start button calls onStart
- Stop button calls onStop
- Error state shows message and retry button
5. **LTTPage Integration tests** (`test_phase4_LTTPage_integration.test.tsx`): ~8 tests
- System Audio tab renders and switches correctly
- Listen Mic tab renders and switches correctly
- ASR variable selects systemAudioASR when source is system-audio
- Full Transcript button hidden for system audio
- ASR variable selects micASR when source is mic
- Full Transcript button hidden for system audio and mic
- QueryInput receives transcript from system audio
- QueryInput receives transcript from mic
- Source switching preserves transcript
**Acceptance Tests** (`backend/app/test/acceptance/test_acceptance_phase4.py`):
- Real `getDisplayMedia` with actual browser (manual — requires human interaction)
- Real `getUserMedia` with actual microphone (manual — requires human interaction)
- Real DashScope ASR with system audio stream
- End-to-end: capture → ASR → transcript → RAG answer
- Real DashScope ASR with microphone stream
- End-to-end: capture → ASR → transcript → RAG answer (both sources)
### Phase 4.7 — Polish & Documentation (0.5 day)
### Phase 4.9 — Polish & Documentation (0.5 day)
**Tasks:**
1. Update `README.md` — add System Audio Capture section with usage instructions, browser compatibility table, and limitations
1. Update `README.md` — add System Audio Capture and Listen Mic sections with usage instructions, browser compatibility table, and limitations
2. Update `development_plan.md` — add Phase 4 row to timeline, mark status
3. Add browser detection helper for compatibility warning
3. Add browser detection helper for system audio compatibility warning
4. Verify production build (`npm run build`)
5. Run full CI regression (`pytest` + `vitest`)
6. Final commit
@ -335,34 +496,51 @@ On Linux, only tab audio is available (not full system audio).
| Decision | Rationale |
|----------|-----------|
| New hook (`useSystemAudioASR`) rather than modifying existing | MediaStream source requires `createMediaStreamSource` (not `createMediaElementSource`), and lifecycle is permission-based (not play/pause events). Separate hook avoids branching complexity. |
| UUID-based `video_id` | No actual video file for system audio. `crypto.randomUUID()` generates unique session IDs. Backend WebSocket already accepts arbitrary strings. |
| Manual Start/Stop (not auto) | `getDisplayMedia()` requires explicit user action (browser policy). Cannot auto-start. |
| No video display in System Audio mode | User watches content in another tab/window. Only capture status and audio controls shown. |
| `video: false` in getDisplayMedia | Audio-only capture reduces bandwidth and permission scope. User only needs to share audio. |
| Hide Full Transcript button for system audio | Same as YouTube — streaming ASR only. Full transcript would require recording and batch processing (future Phase 5). |
| Browser compatibility note in UI | `getDisplayMedia` with audio is Chrome/Edge-only. Non-supporting browsers get clear messaging. |
| New hooks rather than modifying existing | MediaStream source requires `createMediaStreamSource` (not `createMediaElementSource`), and lifecycle is permission-based (not play/pause events). Separate hooks avoid branching complexity. |
| Two separate hooks + shared audio utility | System Audio and Mic share identical audio processing (MediaStream → PCM → WebSocket) but differ in capture API (`getDisplayMedia` vs `getUserMedia`) and UX. Extract shared pipeline to avoid duplication. |
| UUID-based `video_id` (per-session) | No actual video file for live audio. UUID generated once when source tab is selected, reused across Start/Stop cycles within the same session. Regenerated only when switching between sources. Backend WebSocket already accepts arbitrary strings. |
| Manual Start/Stop (not auto) | Both `getDisplayMedia()` and `getUserMedia()` require explicit user action (browser policy). Cannot auto-start. |
| No video display in System Audio or Mic mode | User watches/listens to content elsewhere. Only capture status and audio controls shown. |
| `video: false` in getDisplayMedia | Audio-only capture reduces bandwidth and permission scope. |
| Hide Full Transcript button for both new sources | Streaming ASR only — no video file to batch transcribe. Full transcript would require audio recording (future Phase 5). |
| Browser compatibility note only for System Audio | Mic (`getUserMedia`) is universally supported in all modern browsers. System Audio (`getDisplayMedia` with audio) is Chrome/Edge-only. |
| Mic uses `getUserMedia({ audio: true, video: false })` | Audio-only capture — no camera needed. |
### getDisplayMedia Options
### getDisplayMedia Options (System Audio)
```javascript
const stream = await navigator.mediaDevices.getDisplayMedia({
video: false, // No video needed
video: false,
audio: {
systemAudio: 'include', // Request system audio (tab + full system where supported)
echoCancellation: false, // Don't filter audio
noiseSuppression: false, // Don't filter audio
autoGainControl: false, // Don't adjust volume
systemAudio: 'include',
echoCancellation: false,
noiseSuppression: false,
autoGainControl: false,
}
})
```
**Note on `video: false`:** Setting `video: false` tells the browser we only want audio. However, the browser permission dialog still shows screen/tab selection (there's no "audio-only picker"). The user must select a tab or screen to share — this is a browser limitation, not ours.
**Note on `video: false`:** Setting `video: false` tells the browser we only want audio. However, the browser permission dialog still shows screen/tab selection (there's no "audio-only picker"). The user must select a tab or screen to share — this is a browser limitation.
### getUserMedia Options (Listen Mic)
```javascript
const stream = await navigator.mediaDevices.getUserMedia({
audio: {
echoCancellation: false, // Don't filter audio (pass raw mic input)
noiseSuppression: false, // Don't filter audio
autoGainControl: false, // Don't adjust volume
},
video: false,
})
```
---
## 6. Browser Compatibility
### System Audio (`getDisplayMedia`)
| Platform / Browser | Tab Audio | System Audio | Works? |
|--------------------|-----------|-------------|--------|
| Chrome/Edge (Windows) | ✅ | ✅ | **Best — full support** |
@ -376,11 +554,21 @@ const stream = await navigator.mediaDevices.getDisplayMedia({
```typescript
function isSystemAudioSupported(): boolean {
const isChromium = 'chrome' in window || navigator.userAgent.includes('Chrome')
// Firefox and Safari don't support audio in getDisplayMedia
return isChromium && !navigator.userAgent.includes('Firefox')
}
```
### Listen Mic (`getUserMedia`)
| Platform / Browser | Microphone | Works? |
|--------------------|-----------|--------|
| Chrome/Edge | ✅ | **Full support** |
| Firefox | ✅ | **Full support** |
| Safari | ✅ | **Full support** |
| Mobile browsers | ✅ | **Full support** |
Mic capture is universally supported — no compatibility warning needed.
---
## 7. Test Strategy
@ -389,16 +577,19 @@ function isSystemAudioSupported(): boolean {
| File | Type | Count | Description |
|------|------|-------|-------------|
| `test_phase4_config.py` | Backend integration | 3 | Config toggle, WebSocket accepts UUID |
| `test_phase4_useSystemAudioASR.test.ts` | Frontend unit | ~10 | Hook behavior: capture, permission, audio, WS |
| `test_phase4_config.py` | Backend integration | 4 | Config toggles, WebSocket accepts UUID |
| `test_phase4_useSystemAudioASR.test.ts` | Frontend unit | ~10 | Hook: capture, permission, audio, WS |
| `test_phase4_SystemAudioCapture.test.tsx` | Frontend component | ~5 | UI states: idle, requesting, capturing, error |
| `test_phase4_LTTPage_integration.test.tsx` | Frontend integration | ~5 | Tab switching, ASR unification, Full Transcript |
| `test_integration_phase4.py` | Backend integration | 4 | Config toggle, WebSocket, ASR client |
| `test_acceptance_phase4.py` | Acceptance | 3 | Real browser + real DashScope ASR |
| `test_phase4_useMicASR.test.ts` | Frontend unit | ~8 | Hook: capture, permission, audio, WS |
| `test_phase4_MicCapture.test.tsx` | Frontend component | ~4 | UI states: idle, requesting, listening, error |
| `test_phase4_LTTPage_integration.test.tsx` | Frontend integration | ~8 | Tab switching, ASR unification, Full Transcript |
| `test_integration_phase4.py` | Backend integration | 4 | Config toggles, WebSocket, ASR client |
| `test_acceptance_phase4.py` | Acceptance | 5 | Real browser + real mic + real DashScope ASR |
### Mocking Strategy
- **`getDisplayMedia`**: Mock with `jest.fn()` returning a synthetic MediaStream with an AudioTrack
- **`getUserMedia`**: Mock with `jest.fn()` returning a synthetic MediaStream with an AudioTrack
- **AudioContext**: Use `jest-webgl-mock` or manual mock for AudioContext, ScriptProcessorNode
- **WebSocket**: Mock via `vitest` WebSocket mock (same pattern as Phase 2/3 tests)
- **DashScope ASR**: Mock in CI; real in acceptance tests
@ -410,9 +601,13 @@ function isSystemAudioSupported(): boolean {
### New Files
```
frontend/src/hooks/useSystemAudioASR.ts
frontend/src/hooks/useMicASR.ts
frontend/src/components/SystemAudioCapture.tsx
frontend/src/components/MicCapture.tsx
frontend/src/test/test_phase4_useSystemAudioASR.test.ts
frontend/src/test/test_phase4_SystemAudioCapture.test.tsx
frontend/src/test/test_phase4_useMicASR.test.ts
frontend/src/test/test_phase4_MicCapture.test.tsx
frontend/src/test/test_phase4_LTTPage_integration.test.tsx
backend/app/test/test_phase4_config.py
backend/app/test/test_integration_phase4.py
@ -422,11 +617,11 @@ backend/app/test/acceptance/test_acceptance_phase4.py
### Modified Files
```
frontend/src/pages/LTTPage.tsx ← add "System Audio" tab, wire hook
frontend/src/types/index.ts ← add SystemAudioStatus, SystemAudioASRState
backend/app/core/config.py ← add SYSTEM_AUDIO_ENABLED
frontend/src/pages/LTTPage.tsx ← add "System Audio" + "Listen Mic" tabs, wire hooks
frontend/src/types/index.ts ← add SystemAudioStatus, MicStatus, ASRState types
backend/app/core/config.py ← add SYSTEM_AUDIO_ENABLED, MIC_ENABLED
development_plan.md ← add Phase 4 row
README.md ← add System Audio Capture section
README.md ← add System Audio + Listen Mic sections
```
---
@ -434,13 +629,17 @@ README.md ← add System Audio Capture s
## 9. Acceptance Criteria
- [ ] User can select "System Audio" tab in LTTPage
- [ ] Clicking "Start Capture" opens browser permission dialog
- [ ] On permission grant, audio streams through WebSocket to DashScope ASR
- [ ] Real-time transcript flows into QueryInput
- [ ] User can edit transcript while capture continues
- [ ] User can select "Listen Mic" tab in LTTPage
- [ ] Clicking "Start Capture" (System Audio) opens browser permission dialog
- [ ] Clicking "Start Listening" (Listen Mic) opens microphone permission prompt
- [ ] On permission grant, audio streams through WebSocket to DashScope ASR (both sources)
- [ ] Real-time transcript flows into QueryInput (both sources)
- [ ] User can edit transcript while capture/listening continues
- [ ] "Stop Capture" properly closes MediaStream, AudioContext, WebSocket
- [ ] Permission denied shows clear error message
- [ ] Browser compatibility note shown for non-Chrome browsers
- [ ] "Stop Listening" properly closes MediaStream, AudioContext, WebSocket
- [ ] Permission denied shows clear error message (both sources)
- [ ] Browser compatibility note shown for System Audio on non-Chrome browsers
- [ ] No compatibility warning for Listen Mic (universally supported)
- [ ] All CI tests pass (no regressions)
- [ ] Acceptance tests pass with real DashScope ASR
- [ ] `npm run build` produces clean production build
@ -450,4 +649,5 @@ README.md ← add System Audio Capture s
**File Information**
- Filename: `phase4_system_audio_plan.md`
- Created: 2026-05-09
- Updated: 2026-05-14 — Added Listen Mic as third source; removed YouTube
- Status: Draft — awaiting review before Phase 4.1 implementation begins

View File

@ -54,6 +54,10 @@ class Settings(BaseSettings):
max_video_size_mb: int = 300
supported_video_formats: list[str] = [".mp4", ".webm", ".mov", ".avi", ".mkv"]
# Phase 4 — Live audio capture toggles
system_audio_enabled: bool = True
mic_enabled: bool = True
# Development helpers
model_config = {"env_file": ".env", "env_file_encoding": "utf-8"}

View File

@ -209,7 +209,7 @@ async def _ws_proxy_dashscope(client_ws: WebSocket, loop: asyncio.AbstractEventL
@router.websocket("/ws/asr/{video_id}")
async def ws_asr_endpoint(websocket: WebSocket, video_id: str, language: str = "yue"):
async def ws_asr_endpoint(websocket: WebSocket, video_id: str, language: str = "yue", source: str = "upload"):
settings = get_settings()
client_host = websocket.client.host if websocket.client else "unknown"
@ -220,9 +220,23 @@ async def ws_asr_endpoint(websocket: WebSocket, video_id: str, language: str = "
logger.warning("ws-rejected-no-apikey video_id=%s client=%s", video_id, client_host)
return
if source == "system-audio" and not settings.system_audio_enabled:
await websocket.accept()
await websocket.send_json({"error": "System audio capture is disabled"})
await websocket.close(code=1008, reason="System audio disabled")
logger.warning("ws-rejected-system-audio-disabled video_id=%s client=%s", video_id, client_host)
return
if source == "mic" and not settings.mic_enabled:
await websocket.accept()
await websocket.send_json({"error": "Microphone capture is disabled"})
await websocket.close(code=1008, reason="Mic disabled")
logger.warning("ws-rejected-mic-disabled video_id=%s client=%s", video_id, client_host)
return
await websocket.accept()
loop = asyncio.get_event_loop()
logger.info("ws-connect video_id=%s lang=%s client=%s", video_id, language, client_host)
logger.info("ws-connect video_id=%s lang=%s source=%s client=%s", video_id, language, source, client_host)
try:
await _ws_proxy_dashscope(websocket, loop, language)

View File

@ -0,0 +1,140 @@
"""Phase 4 config tests: system audio and mic capture feature toggles."""
import pytest
from fastapi import FastAPI
from fastapi.testclient import TestClient
@pytest.fixture
def phase4_ws_app(monkeypatch):
monkeypatch.setenv("DASHSCOPE_API_KEY", "sk-test-key")
monkeypatch.setenv("SYSTEM_AUDIO_ENABLED", "true")
monkeypatch.setenv("MIC_ENABLED", "true")
from app.core.config import get_settings
from app.routers.ws_asr import router
get_settings.cache_clear()
app = FastAPI()
app.include_router(router)
return app
class TestWSSourceToggle:
def test_system_audio_source_connects(self, phase4_ws_app):
client = TestClient(phase4_ws_app)
with client.websocket_connect("/ws/asr/test-uuid?source=system-audio") as ws:
pass
def test_mic_source_connects(self, phase4_ws_app):
client = TestClient(phase4_ws_app)
with client.websocket_connect("/ws/asr/test-uuid?source=mic") as ws:
pass
def test_default_source_is_upload(self, phase4_ws_app):
client = TestClient(phase4_ws_app)
with client.websocket_connect("/ws/asr/test-uuid") as ws:
pass
def test_system_audio_disabled_rejects(self, monkeypatch):
monkeypatch.setenv("DASHSCOPE_API_KEY", "sk-test-key")
monkeypatch.setenv("SYSTEM_AUDIO_ENABLED", "false")
from app.core.config import get_settings
from app.routers.ws_asr import router
get_settings.cache_clear()
app = FastAPI()
app.include_router(router)
client = TestClient(app)
with client.websocket_connect("/ws/asr/test-uuid?source=system-audio") as ws:
data = ws.receive_json()
assert "disabled" in data.get("error", "").lower()
def test_mic_disabled_rejects(self, monkeypatch):
monkeypatch.setenv("DASHSCOPE_API_KEY", "sk-test-key")
monkeypatch.setenv("MIC_ENABLED", "false")
from app.core.config import get_settings
from app.routers.ws_asr import router
get_settings.cache_clear()
app = FastAPI()
app.include_router(router)
client = TestClient(app)
with client.websocket_connect("/ws/asr/test-uuid?source=mic") as ws:
data = ws.receive_json()
assert "disabled" in data.get("error", "").lower()
def test_config_system_audio_defaults(monkeypatch, tmp_path):
monkeypatch.delenv("SYSTEM_AUDIO_ENABLED", raising=False)
monkeypatch.setenv("LLM_API_KEY", "sk-test")
monkeypatch.setenv("DP_API_KEY", "sk-test")
monkeypatch.setenv("EMBEDDING_API_KEY", "sk-test")
env_file = tmp_path / ".env"
env_file.write_text("")
monkeypatch.chdir(tmp_path)
from app.core.config import Settings, get_settings
get_settings.cache_clear()
settings = Settings(_env_file=())
assert settings.system_audio_enabled is True
def test_config_mic_defaults(monkeypatch, tmp_path):
monkeypatch.delenv("MIC_ENABLED", raising=False)
monkeypatch.setenv("LLM_API_KEY", "sk-test")
monkeypatch.setenv("DP_API_KEY", "sk-test")
monkeypatch.setenv("EMBEDDING_API_KEY", "sk-test")
env_file = tmp_path / ".env"
env_file.write_text("")
monkeypatch.chdir(tmp_path)
from app.core.config import Settings, get_settings
get_settings.cache_clear()
settings = Settings(_env_file=())
assert settings.mic_enabled is True
def test_config_system_audio_disabled(tmp_path, monkeypatch):
env_file = tmp_path / ".env"
env_file.write_text(
"SYSTEM_AUDIO_ENABLED=false\n"
"LLM_API_KEY=sk-test\n"
"DP_API_KEY=sk-test\n"
"EMBEDDING_API_KEY=sk-test\n"
)
monkeypatch.chdir(tmp_path)
from app.core.config import Settings, get_settings
get_settings.cache_clear()
settings = Settings()
assert settings.system_audio_enabled is False
def test_config_mic_disabled(tmp_path, monkeypatch):
env_file = tmp_path / ".env"
env_file.write_text(
"MIC_ENABLED=false\n"
"LLM_API_KEY=sk-test\n"
"DP_API_KEY=sk-test\n"
"EMBEDDING_API_KEY=sk-test\n"
)
monkeypatch.chdir(tmp_path)
from app.core.config import Settings, get_settings
get_settings.cache_clear()
settings = Settings()
assert settings.mic_enabled is False
def test_config_loads_both_toggles_from_env(tmp_path, monkeypatch):
env_file = tmp_path / ".env"
env_file.write_text(
"SYSTEM_AUDIO_ENABLED=true\n"
"MIC_ENABLED=true\n"
"LLM_API_KEY=sk-test\n"
"DP_API_KEY=sk-test\n"
"EMBEDDING_API_KEY=sk-test\n"
)
monkeypatch.chdir(tmp_path)
from app.core.config import Settings, get_settings
get_settings.cache_clear()
settings = Settings()
assert settings.system_audio_enabled is True
assert settings.mic_enabled is True

2
frontend/.pnpmrc Normal file
View File

@ -0,0 +1,2 @@
onlyBuiltDependencies:
- esbuild

View File

@ -2071,15 +2071,6 @@
"node": ">=6.9.0"
}
},
"node_modules/@types/babel__generator": {
"dev": true
},
"node_modules/@types/babel__template": {
"dev": true
},
"node_modules/@types/babel__traverse": {
"dev": true
},
"node_modules/@types/chai": {
"version": "4.3.20",
"resolved": "https://registry.npmjs.org/@types/chai/-/chai-4.3.20.tgz",
@ -2130,9 +2121,6 @@
"@types/unist": "*"
}
},
"node_modules/@types/jest": {
"dev": true
},
"node_modules/@types/mdast": {
"version": "4.0.4",
"resolved": "https://registry.npmjs.org/@types/mdast/-/mdast-4.0.4.tgz",
@ -2158,7 +2146,6 @@
"undici-types": "~7.19.0"
}
},
"node_modules/@types/prop-types": {},
"node_modules/@types/react": {
"version": "18.3.28",
"resolved": "https://registry.npmjs.org/@types/react/-/react-18.3.28.tgz",

View File

@ -34,5 +34,10 @@
"ts-node": "^10.9.1",
"typescript": "^5.1.6",
"vitest": "^0.34.3"
},
"pnpm": {
"onlyBuiltDependencies": [
"esbuild"
]
}
}

View File

@ -0,0 +1,11 @@
allowBuilds:
'"': true
'[': true
']': true
b: true
d: true
e: true
i: true
l: true
s: true
u: true

View File

@ -0,0 +1,80 @@
import React from 'react'
import { Mic, Loader2, AlertCircle, Circle } from 'lucide-react'
import type { MicStatus } from '../types'
export interface MicCaptureProps {
status: MicStatus
error: string | null
onStart: () => void
onStop: () => void
}
export const MicCapture: React.FC<MicCaptureProps> = ({
status,
error,
onStart,
onStop,
}) => {
if (status === 'error' && error) {
return (
<div className="h-full flex flex-col">
<div className="p-3 bg-red-50 border border-red-200 rounded-lg flex items-start gap-2">
<AlertCircle className="w-4 h-4 text-red-500 shrink-0 mt-0.5" />
<div className="flex-1">
<div className="text-sm text-red-700">{error}</div>
<button
onClick={onStart}
className="mt-2 text-xs text-red-600 hover:text-red-800 font-medium underline"
>
Try Again
</button>
</div>
</div>
</div>
)
}
if (status === 'requesting') {
return (
<div className="h-full flex flex-col items-center justify-center space-y-3">
<Loader2 className="w-8 h-8 text-blue-600 animate-spin" />
<div className="text-sm text-gray-600 font-medium">Waiting for microphone permission...</div>
</div>
)
}
if (status === 'listening' || status === 'stopping') {
return (
<div className="h-full flex flex-col items-center justify-center space-y-4">
<div className="flex items-center gap-2">
<Circle className="w-3 h-3 text-green-500 fill-green-500 animate-pulse" />
<span className="text-sm text-gray-600 font-medium">Listening...</span>
</div>
<div className="flex items-end gap-1 h-8">
<div className="w-2 bg-green-500 rounded-full animate-[bounce_1s_infinite]" style={{ height: '40%', animationDelay: '0ms' }} />
<div className="w-2 bg-green-500 rounded-full animate-[bounce_1s_infinite]" style={{ height: '70%', animationDelay: '150ms' }} />
<div className="w-2 bg-green-500 rounded-full animate-[bounce_1s_infinite]" style={{ height: '55%', animationDelay: '300ms' }} />
</div>
<button
onClick={onStop}
disabled={status === 'stopping'}
className="w-full px-4 py-2 bg-red-600 text-white font-medium rounded hover:bg-red-700 focus:outline-none focus:ring-2 focus:ring-red-500 focus:ring-offset-2 disabled:opacity-50 disabled:cursor-not-allowed disabled:hover:bg-red-600 transition-all duration-200"
>
{status === 'stopping' ? 'Stopping...' : 'Stop Listening'}
</button>
</div>
)
}
return (
<div className="h-full flex flex-col">
<button
onClick={onStart}
className="w-full px-4 py-2 bg-blue-600 text-white font-medium rounded hover:bg-blue-700 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 transition-all duration-200 flex items-center justify-center gap-2"
>
<Mic className="w-4 h-4" />
Start Listening
</button>
</div>
)
}

View File

@ -0,0 +1,42 @@
import React from 'react'
import { Upload, MonitorSpeaker, Mic } from 'lucide-react'
import type { SourceType } from '../types'
interface SourceSelectorProps {
activeSource: SourceType
onSelect: (source: SourceType) => void
}
export const SourceSelector: React.FC<SourceSelectorProps> = ({ activeSource, onSelect }) => {
const tabs: { id: SourceType; label: string; icon: React.ElementType }[] = [
{ id: 'upload', label: 'Upload', icon: Upload },
{ id: 'system-audio', label: 'System Audio', icon: MonitorSpeaker },
{ id: 'mic', label: 'Listen Mic', icon: Mic },
]
return (
<div className="flex gap-1 p-1 bg-gray-100 rounded-lg" role="tablist">
{tabs.map(tab => {
const isActive = activeSource === tab.id
const Icon = tab.icon
return (
<button
key={tab.id}
role="tab"
aria-selected={isActive}
onClick={() => onSelect(tab.id)}
className={[
'flex items-center gap-2 px-4 py-2 rounded-md text-sm font-medium transition-all duration-200',
isActive
? 'bg-white text-blue-700 shadow-sm'
: 'text-gray-500 hover:text-gray-700 hover:bg-gray-50',
].join(' ')}
>
<Icon className="w-4 h-4" />
{tab.label}
</button>
)
})}
</div>
)
}

View File

@ -0,0 +1,86 @@
import React from 'react'
import { MonitorSpeaker, Loader2, AlertCircle, Circle } from 'lucide-react'
import type { SystemAudioStatus } from '../types'
export interface SystemAudioCaptureProps {
status: SystemAudioStatus
error: string | null
onStart: () => void
onStop: () => void
}
export const SystemAudioCapture: React.FC<SystemAudioCaptureProps> = ({
status,
error,
onStart,
onStop,
}) => {
if (status === 'error' && error) {
return (
<div className="h-full flex flex-col">
<div className="p-3 bg-red-50 border border-red-200 rounded-lg flex items-start gap-2">
<AlertCircle className="w-4 h-4 text-red-500 shrink-0 mt-0.5" />
<div className="flex-1">
<div className="text-sm text-red-700">{error}</div>
<button
onClick={onStart}
className="mt-2 text-xs text-red-600 hover:text-red-800 font-medium underline"
>
Try Again
</button>
</div>
</div>
</div>
)
}
if (status === 'requesting') {
return (
<div className="h-full flex flex-col items-center justify-center space-y-3">
<Loader2 className="w-8 h-8 text-blue-600 animate-spin" />
<div className="text-sm text-gray-600 font-medium">Waiting for permission...</div>
</div>
)
}
if (status === 'capturing' || status === 'stopping') {
return (
<div className="h-full flex flex-col items-center justify-center space-y-4">
<div className="flex items-center gap-2">
<Circle className="w-3 h-3 text-green-500 fill-green-500 animate-pulse" />
<span className="text-sm text-gray-600 font-medium">Capturing system audio...</span>
</div>
<div className="flex items-end gap-1 h-8">
<div className="w-2 bg-green-500 rounded-full animate-[bounce_1s_infinite]" style={{ height: '40%', animationDelay: '0ms' }} />
<div className="w-2 bg-green-500 rounded-full animate-[bounce_1s_infinite]" style={{ height: '70%', animationDelay: '150ms' }} />
<div className="w-2 bg-green-500 rounded-full animate-[bounce_1s_infinite]" style={{ height: '55%', animationDelay: '300ms' }} />
</div>
<button
onClick={onStop}
disabled={status === 'stopping'}
className="w-full px-4 py-2 bg-red-600 text-white font-medium rounded hover:bg-red-700 focus:outline-none focus:ring-2 focus:ring-red-500 focus:ring-offset-2 disabled:opacity-50 disabled:cursor-not-allowed disabled:hover:bg-red-600 transition-all duration-200"
>
{status === 'stopping' ? 'Stopping...' : 'Stop Capture'}
</button>
</div>
)
}
return (
<div className="h-full flex flex-col space-y-3">
<button
onClick={onStart}
className="w-full px-4 py-2 bg-blue-600 text-white font-medium rounded hover:bg-blue-700 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 transition-all duration-200 flex items-center justify-center gap-2"
>
<MonitorSpeaker className="w-4 h-4" />
Start Capture
</button>
<div className="p-3 bg-amber-50 border border-amber-200 rounded-lg flex items-start gap-2">
<AlertCircle className="w-4 h-4 text-amber-600 shrink-0 mt-0.5" />
<div className="text-xs text-amber-700 leading-relaxed">
System audio capture works best in Chrome/Edge on Windows/macOS. Firefox and Safari do not support this feature. On Linux, only tab audio is available.
</div>
</div>
</div>
)
}

View File

@ -0,0 +1,191 @@
import { useState, useRef, useCallback, useEffect } from 'react'
import type { ASRMessage } from '../types'
export interface UseMediaStreamASRProps {
wsUrl: string
}
export interface UseMediaStreamASRReturn {
status: 'idle' | 'requesting' | 'streaming' | 'stopping' | 'error'
transcript: string
partialTranscript: string
error: string | null
start: (stream: MediaStream) => void
stop: () => void
}
/**
* Shared audio pipeline: AudioContext ScriptProcessorNode Float32 PCM WebSocket.
* Wrapper hooks (system audio, mic) obtain the MediaStream, then call `start(stream)`.
* Follows the exact audio-processing and WebSocket message pattern from useVideoASR.ts.
*/
export function useMediaStreamASR({ wsUrl }: UseMediaStreamASRProps): UseMediaStreamASRReturn {
const [status, setStatus] = useState<'idle' | 'requesting' | 'streaming' | 'stopping' | 'error'>('idle')
const [transcript, setTranscript] = useState('')
const [partialTranscript, setPartialTranscript] = useState('')
const [error, setError] = useState<string | null>(null)
const wsRef = useRef<WebSocket | null>(null)
const audioContextRef = useRef<AudioContext | null>(null)
const processorRef = useRef<ScriptProcessorNode | null>(null)
const sourceRef = useRef<MediaStreamAudioSourceNode | null>(null)
const streamRef = useRef<MediaStream | null>(null)
const isStreamingRef = useRef(false)
const isManualCloseRef = useRef(false)
const transcriptRef = useRef('')
const lastStashRef = useRef('')
const cleanup = useCallback(() => {
isStreamingRef.current = false
// Stash handling — mirrors useVideoASR stopStreaming lines 101-111
let currentText = transcriptRef.current.trim()
const stash = lastStashRef.current.trim()
if (stash && !currentText.endsWith(stash)) {
currentText += stash
transcriptRef.current = currentText
}
lastStashRef.current = ''
if (currentText) {
setTranscript(currentText)
// Keep partialTranscript populated so the text remains visible in QueryInput
// after the user stops capture/listening. Unlike video ASR, mic/system-audio
// hooks have no onFinalTranscript callback to persist via queryText.
setPartialTranscript(currentText)
}
if (streamRef.current) {
streamRef.current.getTracks().forEach(t => {
t.onended = null
t.stop()
})
streamRef.current = null
}
processorRef.current?.disconnect()
sourceRef.current?.disconnect()
processorRef.current = null
sourceRef.current = null
if (wsRef.current) {
isManualCloseRef.current = true
wsRef.current.close()
wsRef.current = null
}
if (audioContextRef.current) {
audioContextRef.current.close()
audioContextRef.current = null
}
}, [])
const stop = useCallback(() => {
setStatus('stopping')
cleanup()
setStatus('idle')
}, [cleanup])
const start = useCallback((stream: MediaStream) => {
cleanup()
setError(null)
transcriptRef.current = ''
lastStashRef.current = ''
setTranscript('')
setPartialTranscript('')
streamRef.current = stream
isManualCloseRef.current = false
stream.getAudioTracks().forEach(track => {
track.onended = () => {
cleanup()
setStatus('idle')
}
})
try {
// AudioContext + ScriptProcessorNode — mirrors useVideoASR lines 117-136
const audioContext = new AudioContext({ sampleRate: 16000 })
audioContextRef.current = audioContext
const source = audioContext.createMediaStreamSource(stream)
sourceRef.current = source
const processor = audioContext.createScriptProcessor(4096, 1, 1)
processorRef.current = processor
// onaudioprocess — mirrors useVideoASR lines 126-132 exactly
processor.onaudioprocess = (e) => {
const float32Data = e.inputBuffer.getChannelData(0)
const outputData = e.outputBuffer.getChannelData(0)
outputData.set(float32Data)
if (!isStreamingRef.current) return
if (!wsRef.current || wsRef.current.readyState !== WebSocket.OPEN) return
wsRef.current.send(float32Data.buffer)
}
source.connect(processor)
processor.connect(audioContext.destination)
const ws = new WebSocket(wsUrl)
wsRef.current = ws
ws.onopen = () => {
isStreamingRef.current = true
setStatus('streaming')
}
// Message parsing — mirrors useVideoASR lines 51-64 exactly
ws.onmessage = (e) => {
const msg: ASRMessage = JSON.parse(e.data)
if (msg.is_final && msg.full_text) {
transcriptRef.current = msg.full_text
lastStashRef.current = ''
setTranscript(msg.full_text)
setPartialTranscript(msg.full_text)
} else if (msg.delta) {
transcriptRef.current += msg.delta
lastStashRef.current = (msg as any).stash || ''
setTranscript(transcriptRef.current)
setPartialTranscript(transcriptRef.current)
}
}
ws.onerror = () => {
console.error('[useMediaStreamASR] WebSocket error')
setError('WebSocket connection error')
setStatus('error')
isManualCloseRef.current = true
cleanup()
}
ws.onclose = () => {
isStreamingRef.current = false
if (isManualCloseRef.current) return
setError('ASR connection closed unexpectedly')
setStatus('error')
}
} catch (err) {
console.error('[useMediaStreamASR] start failed:', err)
setError(err instanceof Error ? err.message : 'Failed to start audio pipeline')
setStatus('error')
}
}, [wsUrl, cleanup])
useEffect(() => {
return () => {
if (streamRef.current) {
streamRef.current.getTracks().forEach(t => {
t.onended = null
t.stop()
})
}
processorRef.current?.disconnect()
sourceRef.current?.disconnect()
wsRef.current?.close()
audioContextRef.current?.close()
}
}, [])
return { status, transcript, partialTranscript, error, start, stop }
}

View File

@ -0,0 +1,85 @@
import { useState, useEffect } from 'react'
import type { MicStatus } from '../types'
import { useMediaStreamASR } from './useMediaStreamASR'
export function useMicASR({ wsUrl }: { wsUrl: string }) {
const pipeline = useMediaStreamASR({ wsUrl })
const [status, setStatus] = useState<MicStatus>('idle')
const [wrapperError, setWrapperError] = useState<string | null>(null)
useEffect(() => {
switch (pipeline.status) {
case 'streaming':
setStatus('listening')
setWrapperError(null)
break
case 'stopping':
setStatus('stopping')
break
case 'error':
setStatus('error')
setWrapperError(null)
break
case 'idle':
setStatus('idle')
break
}
}, [pipeline.status])
const startListening = async () => {
setWrapperError(null)
setStatus('requesting')
try {
const stream = await navigator.mediaDevices.getUserMedia({
audio: {
echoCancellation: false,
noiseSuppression: false,
autoGainControl: false,
},
video: false,
})
if (stream.getAudioTracks().length === 0) {
stream.getTracks().forEach(t => t.stop())
setStatus('error')
setWrapperError('No microphone input detected')
return
}
pipeline.start(stream)
} catch (err) {
console.error('[useMicASR] getUserMedia failed:', err)
if (err instanceof DOMException && err.name === 'NotAllowedError') {
setStatus('idle')
setWrapperError('Microphone access denied — please allow microphone access in your browser settings')
return
}
if (err instanceof DOMException && err.name === 'NotFoundError') {
setStatus('error')
setWrapperError('No microphone found. Please connect a microphone and try again.')
return
}
if (err instanceof DOMException && err.name === 'NotSupportedError') {
setStatus('error')
setWrapperError('Microphone access is not supported in this browser.')
return
}
setStatus('error')
setWrapperError(err instanceof Error ? err.message : 'Failed to start microphone capture')
}
}
const stopListening = () => {
pipeline.stop()
}
return {
status,
transcript: pipeline.transcript,
partialTranscript: pipeline.partialTranscript,
error: wrapperError ?? pipeline.error,
startListening,
stopListening,
}
}

View File

@ -0,0 +1,91 @@
import { useState, useEffect } from 'react'
import type { SystemAudioStatus } from '../types'
import { useMediaStreamASR } from './useMediaStreamASR'
export function useSystemAudioASR({ wsUrl }: { wsUrl: string }) {
const pipeline = useMediaStreamASR({ wsUrl })
const [status, setStatus] = useState<SystemAudioStatus>('idle')
const [wrapperError, setWrapperError] = useState<string | null>(null)
useEffect(() => {
switch (pipeline.status) {
case 'streaming':
setStatus('capturing')
setWrapperError(null)
break
case 'stopping':
setStatus('stopping')
break
case 'error':
setStatus('error')
setWrapperError(null)
break
case 'idle':
setStatus('idle')
break
}
}, [pipeline.status])
const startCapture = async () => {
setWrapperError(null)
setStatus('requesting')
try {
// getDisplayMedia() SPEC: video:true is REQUIRED.
// Setting video:false causes TypeError (Chrome) or NotSupportedError.
// We capture video but immediately discard it — only audio is used.
const stream = await navigator.mediaDevices.getDisplayMedia({
video: true,
audio: {
systemAudio: 'include',
echoCancellation: false,
noiseSuppression: false,
autoGainControl: false,
},
} as any)
// Stop video tracks immediately — we only need audio
stream.getVideoTracks().forEach((t) => t.stop())
if (stream.getAudioTracks().length === 0) {
stream.getTracks().forEach((t) => t.stop())
setStatus('error')
setWrapperError(
'No audio track found. Make sure to enable "Share audio" in the sharing dialog and select a tab or window that is playing audio.',
)
return
}
pipeline.start(stream)
} catch (err) {
console.error('[useSystemAudioASR] getDisplayMedia failed:', err)
if (err instanceof DOMException) {
if (err.name === 'AbortError' || err.name === 'NotAllowedError') {
setStatus('idle')
setWrapperError('Permission denied — system audio capture requires your explicit permission')
return
}
if (err.name === 'NotSupportedError') {
setStatus('error')
setWrapperError('System audio capture is not supported on this platform. Linux only supports tab audio — try Chrome/Edge on Windows or macOS for full system audio.')
return
}
}
setStatus('error')
setWrapperError(err instanceof Error ? err.message : 'Failed to start system audio capture')
}
}
const stopCapture = () => {
pipeline.stop()
}
return {
status,
transcript: pipeline.transcript,
partialTranscript: pipeline.partialTranscript,
error: wrapperError ?? pipeline.error,
startCapture,
stopCapture,
}
}

View File

@ -1,8 +1,10 @@
import React, { useState, useCallback, useEffect } from 'react'
import React, { useState, useCallback, useEffect, useMemo } from 'react'
import { Loader2, AlertCircle, FileText } from 'lucide-react'
import { Group, Panel, Separator } from 'react-resizable-panels'
import { useQueryDocumentStream } from '../lib/queries'
import { useVideoASR } from '../hooks/useVideoASR'
import { useSystemAudioASR } from '../hooks/useSystemAudioASR'
import { useMicASR } from '../hooks/useMicASR'
import { useFullTranscript } from '../hooks/useFullTranscript'
import { getVideoUrl } from '../lib/api'
import { QueryInput } from '../components/QueryInput'
@ -10,15 +12,20 @@ import { ExtractedQuestionsDisplay } from '../components/ExtractedQuestionsDispl
import { ResponsePanel } from '../components/ResponsePanel'
import { VideoUpload } from '../components/VideoUpload'
import { VideoPlayer } from '../components/VideoPlayer'
import { SourceSelector } from '../components/SourceSelector'
import { SystemAudioCapture } from '../components/SystemAudioCapture'
import { MicCapture } from '../components/MicCapture'
import type { SourceType } from '../types'
export const LTTPage: React.FC = () => {
const [source, setSource] = useState<SourceType>('upload')
const [currentVideoId, setCurrentVideoId] = useState<string | null>(null)
const [queryText, setQueryText] = useState('')
const [videoEl, setVideoEl] = useState<HTMLVideoElement | null>(null)
const queryStream = useQueryDocumentStream()
const asr = useVideoASR({
const uploadASR = useVideoASR({
videoId: currentVideoId ?? '',
videoElement: videoEl,
language: 'yue',
@ -29,6 +36,24 @@ export const LTTPage: React.FC = () => {
const ft = useFullTranscript({ videoId: currentVideoId ?? '' })
const systemAudioWsUrl = useMemo(() => {
const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:'
const host = import.meta.env.VITE_WS_HOST ?? window.location.host
return `${protocol}//${host}/ws/asr/${crypto.randomUUID()}?language=yue&source=system-audio`
}, [])
const micWsUrl = useMemo(() => {
const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:'
const host = import.meta.env.VITE_WS_HOST ?? window.location.host
return `${protocol}//${host}/ws/asr/${crypto.randomUUID()}?language=yue&source=mic`
}, [])
const systemAudioASR = useSystemAudioASR({ wsUrl: systemAudioWsUrl })
const micASR = useMicASR({ wsUrl: micWsUrl })
const asr = source === 'system-audio' ? systemAudioASR
: source === 'mic' ? micASR
: uploadASR
useEffect(() => {
if (ft.fullTranscript) {
setQueryText(ft.fullTranscript)
@ -58,6 +83,9 @@ export const LTTPage: React.FC = () => {
return (
<div className="h-full bg-gray-50">
<div className="px-4 pt-3">
<SourceSelector activeSource={source} onSelect={setSource} />
</div>
<Group
orientation="vertical"
id="ltt-main-group"
@ -69,42 +97,58 @@ export const LTTPage: React.FC = () => {
<Group orientation="horizontal" id="ltt-upper-group" className="h-full">
<Panel id="ltt-upper-left" minSize="30%" defaultSize={50}>
<div className="h-full p-4 overflow-hidden flex flex-col gap-3">
{currentVideoId ? (
<>
<VideoPlayer ref={setVideoEl} src={videoUrl} />
<button
onClick={handleRequestFullTranscript}
disabled={ft.isLoading}
className="shrink-0 flex items-center justify-center gap-2 px-4 py-2 bg-gray-100 hover:bg-gray-200 text-gray-700 font-medium rounded-lg transition-colors duration-200 disabled:opacity-50 disabled:cursor-not-allowed"
>
{ft.isLoading ? (
<Loader2 className="w-4 h-4 animate-spin" />
) : (
<FileText className="w-4 h-4" />
{source === 'upload' ? (
currentVideoId ? (
<>
<VideoPlayer ref={setVideoEl} src={videoUrl} />
<button
onClick={handleRequestFullTranscript}
disabled={ft.isLoading}
className="shrink-0 flex items-center justify-center gap-2 px-4 py-2 bg-gray-100 hover:bg-gray-200 text-gray-700 font-medium rounded-lg transition-colors duration-200 disabled:opacity-50 disabled:cursor-not-allowed"
>
{ft.isLoading ? (
<Loader2 className="w-4 h-4 animate-spin" />
) : (
<FileText className="w-4 h-4" />
)}
<span>{ft.isLoading ? 'Transcribing...' : 'Full Transcript'}</span>
</button>
{ft.error && (
<div
data-testid="full-transcript-error"
className="flex items-start gap-2 text-sm text-red-600"
>
<AlertCircle className="w-4 h-4 shrink-0 mt-0.5" />
<span>{ft.error}</span>
</div>
)}
<span>{ft.isLoading ? 'Transcribing...' : 'Full Transcript'}</span>
</button>
{ft.error && (
<div
data-testid="full-transcript-error"
className="flex items-start gap-2 text-sm text-red-600"
>
<AlertCircle className="w-4 h-4 shrink-0 mt-0.5" />
<span>{ft.error}</span>
</div>
)}
{asr.status === 'error' && (
<div
data-testid="asr-error-indicator"
className="flex items-center gap-2 text-xs text-red-600 bg-red-50 border border-red-200 rounded px-2 py-1"
>
<AlertCircle className="w-3 h-3" />
<span>ASR error</span>
</div>
)}
</>
{uploadASR.status === 'error' && (
<div
data-testid="asr-error-indicator"
className="flex items-center gap-2 text-xs text-red-600 bg-red-50 border border-red-200 rounded px-2 py-1"
>
<AlertCircle className="w-3 h-3" />
<span>ASR error</span>
</div>
)}
</>
) : (
<VideoUpload onUploadSuccess={handleUploadSuccess} />
)
) : source === 'system-audio' ? (
<SystemAudioCapture
status={systemAudioASR.status}
error={systemAudioASR.error}
onStart={systemAudioASR.startCapture}
onStop={systemAudioASR.stopCapture}
/>
) : (
<VideoUpload onUploadSuccess={handleUploadSuccess} />
<MicCapture
status={micASR.status}
error={micASR.error}
onStart={micASR.startListening}
onStop={micASR.stopListening}
/>
)}
</div>
</Panel>

View File

@ -196,3 +196,29 @@ export interface VideoUploadResponse {
size_bytes: number
url: string
}
// Phase 4 — Live audio capture types
export type SourceType = 'upload' | 'system-audio' | 'mic'
export type SystemAudioStatus = 'idle' | 'requesting' | 'capturing' | 'stopping' | 'error'
export type MicStatus = 'idle' | 'requesting' | 'listening' | 'stopping' | 'error'
export interface SystemAudioASRState {
status: SystemAudioStatus
transcript: string
partialTranscript: string
error: string | null
startCapture: () => Promise<void>
stopCapture: () => void
}
export interface MicASRState {
status: MicStatus
transcript: string
partialTranscript: string
error: string | null
startListening: () => Promise<void>
stopListening: () => void
}