CastSprint provides tournament-grade, hardware-accelerated iPhone and iPad mirroring over physical USB. On macOS, it connects directly through Apple’s native CoreMediaIO framework without requiring any companion app installed on your iPhone. On Windows, it utilizes the high-speed USB Personal Hotspot tunnel to stream smooth 60 FPS video into Direct3D 11.
Dual-Platform Pipeline Architecture
Depending on your host operating system, CastSprint employs the optimal driverless pathway supported by Apple hardware:
| Host OS | Mechanism | App Required? | Audio Transport | Target Latency |
|---|---|---|---|---|
| Apple macOS | CoreMediaIO Screen Capture + Metal NV12 | NO (Zero-App) | CoreAudio 48kHz IDAM | 12 – 18 ms |
| Windows 10/11 | USB Personal Hotspot (NCM/CDC) + D3D11 | Optional / AirPlay | WASAPI 48kHz Shared | ~24 ms |
macOS Setup (Zero Mobile App Needed)
On Mac, CastSprint operates entirely driverless using macOS's built-in screen capture device APIs.
- Connect Cable: Plug your iPhone or iPad directly into your Mac using a high-speed USB-C to USB-C or Lightning to USB-C data cable. Avoid unpowered USB hubs.
- Trust This Computer: Unlock your iPhone. When prompted with "Trust This Computer?", tap Trust and enter your device passcode.
- Launch CastSprint Mac: Open CastSprint from your Applications folder. The receiver automatically queries CoreMediaIO with
kCMIOHardwarePropertyAllowScreenCaptureDevicesactivated. - Select Device: In the device list, select your iPhone (listed as
iPhone (USB Screen & System Audio)). - Mirroring Begins: Your live screen instantly renders inside the Metal viewport at full 60 FPS with pure digital game audio!
Windows USB Hotspot Setup
Windows PCs do not natively expose Apple CoreMediaIO interfaces. To achieve near-zero latency on Windows without installing mobile sideloaded apps, CastSprint routes a dedicated high-speed link over USB Personal Hotspot:
- Connect your iPhone to your Windows PC with a high-quality USB cable.
- Tap Trust This Computer on your iPhone and enter your passcode.
- Open iOS Settings > Personal Hotspot and turn it ON. If prompted, choose USB Only (do not enable Wi-Fi hotspot).
- Windows Network Connections will register the high-speed
Apple Mobile Device Ethernetadapter. - Launch CastSprint Receiver on Windows. Select ⚡ USB Hotspot (Wired).
- On your iPhone, swipe down to open Control Center, tap Screen Mirroring, and choose CastSprint Desktop.
Interactive Touchscreen Play
Unlike macOS 15 Sequoia's built-in "iPhone Mirroring.app" (which locks your iPhone screen with an unusable placeholder slate), CastSprint keeps your physical phone completely unlocked and responsive.
You play on your iPhone with zero touchscreen lag, 120Hz/60Hz touch sampling rate, and full multi-finger gaming controls, while CastSprint mirrors the clean video and game sound to your computer for stream production.
USB Screen Capture vs Continuity Camera
CastSprint explicitly separates and filters out Continuity Camera (webcam) feeds. Many generic tools accidentally connect to your iPhone's rear camera instead of its screen. CastSprint validates CMIO device transport keys so that only the authentic display framebuffer is captured.
Wired Troubleshooting Checklist
- Phone does not appear in CastSprint: Ensure the cable is a data cable (many cheap cables are power-only). Unplug, reconnect, and verify the "Trust" prompt appears.
- Black screen on commercial apps: DRM-protected streaming apps (Netflix, Disney+, Prime Video) intentionally blackout mirror feeds under HDCP/FairPlay rules. Mobile games and all creator apps mirror with 100% visibility.
- Frame drops on Windows: Ensure the USB cable is plugged into a rear motherboard USB 3.0/3.1 port rather than a front-panel splitter.