*** The Pro version can save video record and snapshot into external SD Card or USB Disk,  supports loop-recording and provides some extra features (e.g. 'Picture In Picture', 'Display Video On Lock Screen', 'Auto-record after connected' and so on) from General Settings and without ads***
Tip: 
Supports UVC WebCam WITH microphone and UVC video grabber WITH audio input(Up to 4K via HDMI, Supports progressive and interlaced video).  MJPEG(or H.264, H.265, HEVC) format is required when using 2 cameras at the same time.

Please click USB icon from toolbar to open Device dialog to open device if the system unable to detect your device.
Please use a good quality OTG cable and ensure power supply
Please ensure that the 2 cameras have sufficient power supply. It is recommended to use HUB with external power supply! Some devices may need to bridge HUB to work properly, e.g. Elgato Cam link.
Using HEVC for video recording/streaming requires Android 5.0 or above, and the device must supports HEVC codec.

See the video for more info: https://youtu.be/B569qfWx83U

"USB Dual Camera" can let your android device connect to 2 USB WebCams or video capture cards via USB-OTG at the same time. You can record video or capture snapshot., OR turn your phone into a wireless IP Camera via build-in RTSP and HTTP Server for security monitoring WITH Bi-directional audio support, you can use your browser to view, of course, include "IP Camera" App.

"USB Dual Camera" can push the video and audio to RTMP/SRT live media server and use for network live broadcast. It supports the rtmps security protocol and SRT protocol and it can also push the media to multiple media server at the same time. It also supports HEVC over RTMP and can be used for YouTube Live currently.

"USB Dual Camera" can record video into two mp4 files synchronously if you connect to 2 USB WebCams at the same time and record. This feature can also records audio separately if both of the cameras have audio input. It can also set to create full Side-by-Side (SBS) 3D video. You can use your 3D video player to view 3D video. It can mix audio automatically if both cameras have audio input.

"USB Dual Camera" can add timestamp, GPS, speed and other info on the video frames while recording.

USB Dual Camera can seamless switching between foreground and background. Just press 'Enter background' from menu. The recording will not interrupted during switching!

It support auto video recording which based on Motion Detection and the video record can be uploaded to FTP server automatically and notify you via Email!

For Pro version

"USB Dual Camera" supports loop-recording. Can set auto-segment when recording and auto-delete old video archives when no enough storage. "USB Dual Camera" can be used as "Dash Cam"

Bi-directional audio requires IP Camera App, you can get it from https://play.google.com/store/apps/details?id=com.shenyaocn.android.WebCam 

IMPORTANT! On Android 9 and above, Camera permission is required to get fully USB Video device access. Don't worry, the application does not contain any function/code to visit built-in camera because it is unnecessary.

This is userspace driver so it used for the app only. Android does not allow to install kernel driver so it unable to use for third-party apps.

Connect 2 UVC devices for recording and broadcast video/audio stream