Németh Márton wrote: > Hi, > > I am currently working on a project to test video devices (webcams, > tuners, etc.) which using the V4L2 API ( http://v4l-test.sourceforge.net/ ). > > There are a lot of video devices which are connected to the computer > via USB. If I have a device available I can run the test against it. > Some problems are exists, for example it is not so easy to create > an automatic test which unplugs an USB device at a certain test step and > replugs it later. > > If a hardware device is not available the related software driver cannot > be tested either. > > I wonder if a software "USB loopback device" driver already exists, > similar to the "lo" device in networking. This device would show up > as a USB hardware device when it is asked to do so from the user > space. Then the user space "simulator" would receive all USB packets > which would normally be sent to the USB device and the "simulator" > could react and send USB packets in the other direction. > > Do you know about such a driver? If not, do you think that the USB > subsystem has a point or an interface where this can be implemented? There's a vloopback for v4l devices. It's the only way to use certain webcams with a lot of linux apps, but it's sadly unmaintained: http://www.lavrsen.dk/twiki/bin/view/Motion/VideoFourLinuxLoopbackDevice The latest svn does build with the latest kernel though... -- Phil Dibowitz phil@xxxxxxxx Open Source software and tech docs Insanity Palace of Metallica http://www.phildev.net/ http://www.ipom.com/ "Never write it in C if you can do it in 'awk'; Never do it in 'awk' if 'sed' can handle it; Never use 'sed' when 'tr' can do the job; Never invoke 'tr' when 'cat' is sufficient; Avoid using 'cat' whenever possible" -- Taylor's Laws of Programming
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