How to simulate a webcam device [closed]

Question

I am working on a project which I need to synthesize a video from existing frames and then format it exactly like a webcam device and make it available to external computers. In other words, this USB output should look exactly as if it was generated by a webcam. Can someone provide some hints about any existing library or any methodology to do this? The target system to create "webcam" output via USB is UBUNTU.

Thanks

Answer 1

Web cams are usually accessed through a library or the operating system rather than as low level USB devices. In python, one option to read webcam frame is https://github.com/gebart/python-v4l2capture or use my cross platform fork (including windows): https://github.com/TimSC/libvideolive

If you want to create a video stream that is accessible to other computers, you either need to emulate a webcam or an IP camera. A webcam can be emulated on windows by creating a custom media source. https://msdn.microsoft.com/en-us/library/windows/desktop/ms700134%28v=vs.85%29.aspx On linux, you need to stream data to v4l2loopback https://github.com/umlaeute/v4l2loopback. To emulate an IP camera, a good starting point is to base it on the tools available at http://live555.com/

Answer 2

OK after updating your requirements I guess the following can help

first you create a program that prepare the frames

Mat frame = imread('<file>');
std::vector<uchar> buff;    
cv::imencode(".jpg", frame, buff);
for (auto i = buff.begin(); i != buff.end(); ++i)
   std::cout << *i ;

then you can use v4l2loopback combined with ffmpeg to emulate the webcam and pipe the output from the above program ./app | ffmpeg -re -i pipe:0 -f v4l2 /dev/video1

now the /dev/video1 is a virtual webcam (video device). Note that is not USB output. But I hope that's what you want.

For further info you can check this and this

---

UPDATE

you can always create another program that capture the output from /dev/video1 and then uses libusb to write it to another USB port which will achieve what do you want (webcam output to usb port

check this for an example