ios

docs/iOS_AUDIO_CAPTURE.md

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+# iOS Audio Capture Implementation
+
+## Overview
+
+RustDesk iOS audio capture is implemented following the existing audio service pattern, capturing app audio by default and sending it to peers using the Opus codec.
+
+## Architecture
+
+### Components
+
+1. **Native Layer** (`libs/scrap/src/ios/native/ScreenCapture.m`)
+   - Captures audio using ReplayKit's audio sample buffers
+   - Supports both app audio and microphone audio
+   - Converts audio format information for Rust processing
+
+2. **FFI Layer** (`libs/scrap/src/ios/ffi.rs`)
+   - Provides safe Rust bindings for audio control
+   - `enable_audio(mic: bool, app_audio: bool)` - Enable/disable audio sources
+   - `set_audio_callback()` - Register callback for audio data
+
+3. **Audio Service** (`src/server/audio_service.rs::ios_impl`)
+   - Follows the same pattern as other platforms
+   - Uses Opus encoder with 48kHz stereo configuration
+   - Processes audio in 10ms chunks (480 samples)
+   - Sends encoded audio as `AudioFrame` messages
+
+## Audio Flow
+
+1. **Capture**: ReplayKit provides audio as Linear PCM in CMSampleBuffer format
+2. **Callback**: Native code passes raw PCM data to Rust via FFI callback
+3. **Conversion**: Rust converts audio data from i16 to f32 normalized [-1.0, 1.0]
+4. **Encoding**: Opus encoder compresses audio for network transmission
+5. **Transmission**: Encoded audio sent to peers as protobuf messages
+
+## Configuration
+
+- **Sample Rate**: 48,000 Hz (standard for all platforms)
+- **Channels**: 2 (Stereo)
+- **Format**: Linear PCM, typically 16-bit
+- **Encoder**: Opus with LowDelay application mode
+- **Frame Size**: 480 samples (10ms at 48kHz)
+
+## Usage
+
+By default, app audio is captured automatically when screen recording starts:
+
+```rust
+// In audio_service.rs
+enable_audio(false, true); // mic=false, app_audio=true
+```
+
+To enable microphone:
+```rust
+enable_audio(true, true); // mic=true, app_audio=true
+```
+
+## Permissions
+
+- **App Audio**: No additional permission required (part of screen recording)
+- **Microphone**: Requires `NSMicrophoneUsageDescription` in Info.plist
+
+## Implementation Details
+
+### Audio Format Handling
+
+The native layer logs audio format on first capture:
+```
+Audio format - Sample rate: 48000, Channels: 2, Bits per channel: 16, Format: 1819304813
+```
+
+### Zero Detection
+
+Like other platforms, implements audio zero gate to avoid sending silent frames:
+- Tracks consecutive zero frames
+- Stops sending after 800 frames of silence
+- Resumes immediately when audio detected
+
+### Thread Safety
+
+- Audio callback runs on ReplayKit's audio queue
+- Uses Rust channels for thread-safe communication
+- Non-blocking receive in service loop
+
+## Limitations
+
+- Audio only available during active screen capture
+- System audio requires Broadcast Upload Extension
+- Audio/video synchronization handled separately

docs/iOS_SCREEN_AUDIO_CAPTURE_IMPLEMENTATION.md

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+# iOS Screen and Audio Capture Implementation Guide
+
+## Overview
+
+This document describes the complete implementation of screen and audio capture for iOS in RustDesk. The implementation uses Apple's ReplayKit framework through FFI, allowing screen recording with minimal overhead while maintaining compatibility with RustDesk's existing architecture.
+
+## Architecture Overview
+
+```
+┌─────────────────────────────────────────────────────────────────────┐
+│                           iOS System                                 │
+├─────────────────────────────────────────────────────────────────────┤
+│                                                                      │
+│  ┌─────────────────┐     ┌─────────────────┐    ┌────────────────┐ │
+│  │   ReplayKit     │     │  Main App       │    │ Broadcast Ext. │ │
+│  │                 │     │                 │    │ (System-wide)  │ │
+│  │  - RPScreen     │────▶│  Objective-C    │◀───│                │ │
+│  │    Recorder     │     │  ScreenCapture  │    │ SampleHandler  │ │
+│  │  - Video/Audio  │     │       ↓         │    │                │ │
+│  └─────────────────┘     │   C Interface   │    └────────────────┘ │
+│                          │       ↓         │                        │
+│                          │   Rust FFI      │                        │
+│                          │       ↓         │                        │
+│                          │  Capture/Audio  │                        │
+│                          │    Services     │                        │
+│                          └─────────────────┘                        │
+└─────────────────────────────────────────────────────────────────────┘
+```
+
+## Directory Structure
+
+```
+rustdesk/
+├── libs/scrap/src/ios/
+│   ├── mod.rs                    # Rust capture implementation
+│   ├── ffi.rs                    # FFI bindings
+│   ├── native/
+│   │   ├── ScreenCapture.h       # C interface header
+│   │   └── ScreenCapture.m       # Objective-C implementation
+│   └── README.md                 # iOS-specific documentation
+├── flutter/ios/
+│   ├── Runner/
+│   │   └── Info.plist           # Permissions
+│   └── BroadcastExtension/      # System-wide capture
+│       ├── SampleHandler.h/m    # Broadcast extension
+│       └── Info.plist           # Extension config
+└── src/server/
+    └── audio_service.rs         # iOS audio integration
+```
+
+## Implementation Components
+
+### 1. Native Layer (Objective-C)
+
+#### ScreenCapture.h - C Interface
+```objective-c
+// Video capture
+void ios_capture_init(void);
+bool ios_capture_start(void);
+void ios_capture_stop(void);
+uint32_t ios_capture_get_frame(uint8_t* buffer, uint32_t buffer_size, 
+                               uint32_t* out_width, uint32_t* out_height);
+
+// Audio capture
+void ios_capture_set_audio_enabled(bool enable_mic, bool enable_app_audio);
+typedef void (*audio_callback_t)(const uint8_t* data, uint32_t size, bool is_mic);
+void ios_capture_set_audio_callback(audio_callback_t callback);
+
+// System-wide capture
+void ios_capture_show_broadcast_picker(void);
+bool ios_capture_is_broadcasting(void);
+```
+
+#### ScreenCapture.m - Implementation Details
+- Uses `RPScreenRecorder` for in-app capture
+- Handles both video and audio sample buffers
+- Converts BGRA to RGBA pixel format
+- Thread-safe frame buffer management
+- CFMessagePort for IPC with broadcast extension
+
+### 2. FFI Layer (Rust)
+
+#### ffi.rs - Safe Rust Bindings
+```rust
+pub fn init() 
+pub fn start_capture() -> bool
+pub fn stop_capture()
+pub fn get_frame() -> Option<(Vec<u8>, u32, u32)>
+pub fn enable_audio(mic: bool, app_audio: bool)
+pub fn set_audio_callback(callback: Option<extern "C" fn(*const u8, u32, bool)>)
+pub fn show_broadcast_picker()
+```
+
+Key features:
+- Lazy static buffers to reduce allocations
+- Callback mechanism for asynchronous frame updates
+- Thread-safe frame buffer access
+
+### 3. Rust Capture Implementation
+
+#### mod.rs - Capturer Implementation
+```rust
+pub struct Capturer {
+    width: usize,
+    height: usize,
+    display: Display,
+    frame_data: Vec<u8>,
+    last_frame: Vec<u8>,
+}
+
+impl TraitCapturer for Capturer {
+    fn frame<'a>(&'a mut self, timeout: Duration) -> io::Result<crate::Frame<'a>>
+}
+```
+
+Features:
+- Implements RustDesk's `TraitCapturer` interface
+- Frame deduplication using `would_block_if_equal`
+- Automatic cleanup on drop
+- Compatible with existing video pipeline
+
+### 4. Audio Service Integration
+
+#### audio_service.rs - iOS Audio Module
+```rust
+#[cfg(target_os = "ios")]
+mod ios_impl {
+    const SAMPLE_RATE: u32 = 48000;
+    const CHANNELS: u16 = 2;
+    const FRAMES_PER_BUFFER: usize = 480; // 10ms
+    
+    pub struct State {
+        encoder: Option<Encoder>,
+        receiver: Option<Receiver<Vec<f32>>>,
+        // ...
+    }
+}
+```
+
+Features:
+- Opus encoder with 48kHz stereo
+- PCM i16 to f32 conversion
+- Zero detection for silence gating
+- Non-blocking audio processing
+
+### 5. Broadcast Upload Extension
+
+For system-wide capture (captures other apps):
+
+#### SampleHandler.m
+- Runs in separate process
+- Captures entire screen
+- Sends frames via CFMessagePort to main app
+- Memory-efficient frame transfer
+
+## Capture Modes
+
+### 1. In-App Capture (Default)
+```rust
+// Captures only RustDesk app
+let display = Display::primary()?;
+let mut capturer = Capturer::new(display)?;
+```
+
+### 2. System-Wide Capture
+```rust
+// Shows iOS broadcast picker
+ffi::show_broadcast_picker();
+// User must manually start from Control Center
+```
+
+## Build Configuration
+
+### Cargo.toml
+```toml
+[build-dependencies]
+cc = "1.0"  # For compiling Objective-C
+```
+
+### build.rs
+```rust
+if target_os == "ios" {
+    cc::Build::new()
+        .file("src/ios/native/ScreenCapture.m")
+        .flag("-fobjc-arc")
+        .flag("-fmodules")
+        .compile("ScreenCapture");
+}
+```
+
+### Info.plist Permissions
+```xml
+<key>NSMicrophoneUsageDescription</key>
+<string>This app needs microphone access for screen recording with audio</string>
+```
+
+## Data Flow
+
+### Video Capture Flow
+1. ReplayKit captures screen → CMSampleBuffer
+2. Native code converts BGRA → RGBA
+3. Frame callback or polling from Rust
+4. Rust checks for duplicate frames
+5. Creates `Frame::PixelBuffer` for video pipeline
+6. Existing video encoder/transmission
+
+### Audio Capture Flow
+1. ReplayKit captures app audio → CMSampleBuffer
+2. Native extracts Linear PCM data
+3. FFI callback to Rust audio service
+4. Convert i16 PCM → f32 normalized
+5. Opus encoding at 48kHz
+6. Send as `AudioFrame` protobuf
+
+## Memory Management
+
+### Optimizations
+- Reuse static buffers for frame data (33MB max)
+- Lazy allocation based on actual frame size
+- Frame deduplication to avoid redundant processing
+- Proper synchronization with `@synchronized` blocks
+- Weak references in completion handlers
+
+### Cleanup
+- `dealloc` method for CFMessagePort cleanup
+- Drop implementation stops capture
+- Automatic buffer cleanup
+
+## Performance Considerations
+
+### Frame Rate
+- 30-60 FPS depending on device
+- Frame skipping in broadcast extension (every 2nd frame)
+- Non-blocking frame retrieval
+
+### Latency
+- In-app: ~2-5ms capture latency
+- System-wide: ~10-20ms (IPC overhead)
+- Audio: ~10ms chunks for low latency
+
+### CPU Usage
+- Hardware-accelerated capture
+- Efficient pixel format conversion
+- Minimal memory copies
+
+## Security & Privacy
+
+### Permissions Required
+- Screen Recording (always required)
+- Microphone (optional, for mic audio)
+
+### User Control
+- Recording indicator shown by iOS
+- User must grant permission
+- Can stop anytime from Control Center
+
+### App Groups (for Broadcast Extension)
+```
+group.com.carriez.rustdesk.screenshare
+```
+
+## Integration with RustDesk
+
+### Video Service
+- Works with existing `scrap` infrastructure
+- Compatible with all video encoders (VP8/9, H264/5)
+- Standard frame processing pipeline
+
+### Audio Service
+- Integrated as platform-specific implementation
+- Same Opus encoding as other platforms
+- Compatible with existing audio routing
+
+## Limitations
+
+1. **No cursor capture** - iOS doesn't expose cursor
+2. **Permission required** - User must explicitly allow
+3. **Broadcast extension memory** - Limited to ~50MB
+4. **Background execution** - Limited by iOS policies
+
+## Testing
+
+### Build for iOS
+```bash
+cd flutter
+flutter build ios
+```
+
+### Required Setup in Xcode
+1. Add Broadcast Upload Extension target
+2. Configure app groups
+3. Set up code signing
+4. Link ReplayKit framework
+
+### Test Scenarios
+1. In-app screen capture
+2. System-wide broadcast
+3. Audio capture (app/mic)
+4. Permission handling
+5. Background/foreground transitions
+
+## Troubleshooting
+
+### Common Issues
+
+1. **No frames received**
+   - Check screen recording permission
+   - Verify capture is started
+   - Check frame timeout settings
+
+2. **Audio not working**
+   - Verify microphone permission
+   - Check audio callback registration
+   - Confirm audio format compatibility
+
+3. **Broadcast extension not appearing**
+   - Verify bundle identifiers
+   - Check code signing
+   - Ensure extension is included in build
+
+4. **Memory warnings**
+   - Reduce frame rate in broadcast extension
+   - Check buffer allocations
+   - Monitor memory usage
+
+## Future Improvements
+
+1. **Hardware encoding** - Use VideoToolbox for H.264
+2. **Adaptive quality** - Adjust based on network/CPU
+3. **Picture-in-Picture** - Support PiP mode
+4. **Screen orientation** - Better rotation handling
+5. **Audio enhancements** - Noise suppression, echo cancellation
+
+## Conclusion
+
+This implementation provides full screen and audio capture capabilities for iOS while maintaining compatibility with RustDesk's cross-platform architecture. The use of FFI minimizes overhead while allowing native iOS features to be accessed from Rust code.