When diagnosing issues, always follow the signal path from mobile source to computer receiver and streaming software. Use this reference matrix to quickly resolve common setup hurdles.
Diagnostic Workflow
1. Mobile Device
Unlocked & permitted
Unlocked & permitted
2. Physical Bus / LAN
Data cable / 5 GHz Wi-Fi
Data cable / 5 GHz Wi-Fi
3. CastSprint Receiver
Handshake & first frame
Handshake & first frame
4. OBS Studio
WGC / App Audio Capture
WGC / App Audio Capture
Black Screens & DRM Restrictions
| Symptom | Root Cause | Resolution |
|---|---|---|
| Black screen in commercial media apps | Apple FairPlay or Widevine DRM protection (Netflix, Disney+, etc.) | By law and OS security policy, copyrighted DRM streams cannot be captured. Close DRM video apps and return to gameplay. |
| OBS Window Capture shows a black frame | CastSprint receiver was minimized to taskbar | Do not minimize CastSprint. Leave it behind OBS or on a second monitor. |
| Screen rotation freezes aspect ratio | OBS source transform locked to bounding box | In OBS source properties, set bounding box type to Scale to inner bounds. |
USB & ADB Connection Failures
| Symptom | Cause | Fix |
|---|---|---|
adb devices shows "unauthorized" | RSA debugging authorization prompt missed | Unplug, reconnect, unlock phone, and check "Always allow from this computer". |
| Phone not recognized at all | Charge-only cable or missing OEM USB driver | Swap cable for a verified USB data cable. On Windows, install the OEM driver (Samsung/Google/Universal ADB). |
| Android app says "Waiting for receiver" | Reverse port forwarding command omitted | Run adb reverse tcp:27183 tcp:27183 in your terminal. |
Wi-Fi & mDNS Discovery Issues
- Discovered list is empty: Your router may have multicast DNS (mDNS) filtering or AP Client Isolation enabled. Switch your phone off the "Guest" Wi-Fi onto your primary 5 GHz network.
- Manual IP fallback: If mDNS is blocked, enter your desktop computer's local IP address (e.g.
192.168.1.150:27183) and the 6-digit session PIN directly in the mobile app. - Session PIN mismatch: Ensure the PIN entered on your mobile device matches the exact PIN shown in the CastSprint desktop window.
Audio Desync & Echo Prevention
Avoiding Double Audio / EchoIf your stream hears double game audio, you likely added both Desktop Audio and Application Audio Capture in OBS. Disable Desktop Audio for CastSprint, or mute CastSprint in Desktop Audio mixer properties.
To adjust audio latency alignment on the fly, press [ or ] in CastSprint Receiver to trim synchronization in 10ms steps.
Submitting a Bug Report
If you encounter an unhandled crash or reproducible bug, please submit an issue on GitHub with:
- Mobile device model and exact OS version (e.g. iPhone 15 Pro, iOS 18.1 / Galaxy S24, Android 14)
- Desktop computer operating system build (e.g. macOS Sonoma 14.6 M2 / Windows 11 23H2)
- Connection method used (USB Cable vs Wi-Fi LAN)
- Desktop receiver terminal / console output log