Hi Martin, Sorry for this slightly off topic mail, its more about the capabilities of webcams than the driver..
>> The question now is, which framerate could I expect >> from 5 UVC USB2 cameras connected to a single laptop? Or is there a >> principal problem of using that amount of cameras at the same time? > > I don't have the equipment to do this test with me at the moment but to > give you something to work with: > > - The UVC overhead is minimal. > - There is obviously some USB overhead but it should be rather small > compared to the video stream. > - In YUV mode, the size of one frame is 1.5*height*width. > - In MJPEG mode, the size is somewhat unpredictable but obviously tends > to be much smaller. You can test this using the -c option of luvcview. The YUV mode definitely leads to a huge amount of data in that case. (if 15 or 30 fps is desired). With a firewire camera at least the capture wouldn't be a problem (no copying involved, all data transfered via DMA), saving to disk probably is the killer there. At first I'm looking at dumping the images right to disk. So a camera with MJPEG output would be definitely a nice thing to have, because it would probably lead to a manageable amount of data. Unfortunately, I would like to know a bit more about the capabilities of the recent logitech webcams before I buy one, just to find that it doesn't do the things I need. MJPEG support is good news, but there is not information on the web for with resolution and framerates it is supported. All information from logitech is just marketing bubbles, no hard facts there, like which mode is available at what image size and frame rate. The only thing I found out is that the Fusion doesn't support more than 7.5 fps in its highest resolution (in RGB24 mode?): http://ghonis2.ho8.com/fusiontest5.html The question now is what the limits for MJPEG capturing are. Given the lack of tech info on the web, has anybody with a Fusion or QC 5000 found out framerates (and maybe average size of the data stream) for MJPEG captures at 640x480 and 1280x960? > This should give you an idea of the amount of data you have. Whether > your PC can handle it, is a whole other story. :-) I hope that the MPEG streams can be saved to disk in realtime. If I have to use YUV, maybe compression using ffmpeg might buy something, but I guess I'd be limited to 640x480 with less than 30 fps. ciao Pablo _______________________________________________ Linux-uvc-devel mailing list [email protected] https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
