Hi Rich, On Thursday 12 June 2008, Rich wrote: > So, I got this new webcam today - it is a Philips SPC 1300NC (0471:0331). > Unlike other webcam's I've had (I had a logitech QC pro 5000, which worked > marvelously with the UVC driver, but it caught fire unfortunately - it > would have a slow shutter speed and blur, but the framerate was always 30 > when I asked it to be), instead of sending a constant frame rate, no matter > the lighting conditions, this camera seems to sync the framerate with the > shutter speed - in less-than-daylight conditions, it sends 5 frames per > second out, after telling what ever program (luvcview, mplayer, gst-launch, > or a simple python video-grabbing script I wrote, available here: > http://www.ndeschildre.net/2008/04/29/python-and-webcam-part-2/ ) I try it > with to use 30 FPS. luvcview shows FPS at the top, and indeed the camera's > output goes from 30FPS if I shove it up to my computer monitor, to 5 FPS if > I point it at me. It gives somewhat comical results when I record a video > as it plays back at 30FPS, so 30 seconds of recording becomes a 6 second > clip of me moving very fast. Unfortunately, comical was not why I bought > the camera. > > I read a post around the 19th of May on this list regarding a similar issue > with an SPC 1000NC camera, though I never heard anything further regarding > it. Does anyone know if this is a hardware issue that was 'patched' by > philips' Windows drivers (90FPS and 6 megapixels my ass!) and I should just > return this turd, or is it something that could be fixed with software?
Most webcams have an auto-exposure feature enabled by default that will raise the exposure time in low light conditions, making the frame rate drop. Auto-exposure can be turned off using the V4L2_CID_EXPOSURE_AUTO control on models that export the auto-exposure control. The SPC1300NC seems to support that. You will not be able to get more than 30fps though. The UVC descriptors report frame rates up to 30fps only, and I think Philips use software interpolation to achieve 90fps (even though they could use private commands to switch to higher frame rates, but I really doubt that). > The only thing that swayed me from buying another QC5000 was the 1280x1024 > capture, but it only goes to 15FPS with this camera, and I have a real > camera if I need to take pictures. The QC 5000 is limited to 15fps at 1280x1024 but can probably achieve higher frame rates at lower resolutions. > Let me know if you all need anymore > information, or any thoughts on the subject. Thanks, Best regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list [email protected] https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
