Hi Theodore > > It looks like I'll have to keep checking eBay for cheap USB v3 (HD) > > webcams periodically. > > Which somebody will need to support because they will probably not work > out of the box with an OEM driver CD ;-)
Ah yes, there is that aspect to think about before making a purchase :-). Actually, I think Linus will be pretty keen to rush support for USB v3 webcams into the kernel. Hopefully it won't take too long for a few cheapies to work in Linux. > Some of the cheap cameras do work pretty well, actually. But as far as I > know any resolution better than 640*480 seems to be pretty unusual. Lots > of "interpolated" higher resolution meaning they have inflated the > pictures, of course. But some of the 640x480 cameras do better than > others. And also I should point out that if 4 fps is OK with you then some > of the cameras do not even do compression. If you could get hold of an old > SQ905 camera that will do 640x480 it runs on bulk transport and there is > no compression of frame data at all. Also, what is interesting is that > with all the cheap cameras they cut corners, of course. But the SQ905 > cameras always seemed to me to tend to have better optics than a lot of > the other cheap cams. Where they really cut down on features was with the > controller chip. It will do practically nothing compared to some others. > The SQ905 used to be advertised as the cheapest camera controller chip on > the market, once upon a time. But the images one gets from those cameras > sometimes are not half bad. Thanks for letting me know about that model. I think I'll be able to stay with my SN9C201 for now, especially since I've started using Motion's auto-brightness setting. It almost seemed like the sun was in the room with me last night :-). > Also I should mention that if one wants to get better images out then it > is best somehow to capture and save the raw data and process it later. > This is true for any camera which either produces an uncompressed bitmap > raw image, and also for any camera which does compression of said bitmap > image before sending it down to the computer. Everything but JPEG, pretty > much. Why is this? Because the image processing used with webcams must > necessarily have speed as the number one priority, else the frame rate > suffers severely. If one is not thus constrained, it is possible to do a > much better job with that raw data. But remember that you can maximize > image quality, or you can maximize frame rate. Choose one of the two. Yeah, I had a feeling that would be the case. The following is an extract from Motion's configuration file. If I want to maximise quality, which of these options do you think I should choose? As you can see, I've been using the default one (8) lately. # v4l2_palette allows to choose preferable palette to be use by motion # to capture from those supported by your videodevice. (default: 8) # E.g. if your videodevice supports both V4L2_PIX_FMT_SBGGR8 and # V4L2_PIX_FMT_MJPEG then motion will by default use V4L2_PIX_FMT_MJPEG. # Setting v4l2_palette to 1 forces motion to use V4L2_PIX_FMT_SBGGR8 # instead. # # Values : # V4L2_PIX_FMT_SN9C10X : 0 'S910' # V4L2_PIX_FMT_SBGGR8 : 1 'BA81' # V4L2_PIX_FMT_MJPEG : 2 'MJPEG' # V4L2_PIX_FMT_JPEG : 3 'JPEG' # V4L2_PIX_FMT_RGB24 : 4 'RGB3' # V4L2_PIX_FMT_UYVY : 5 'UYVY' # V4L2_PIX_FMT_YUYV : 6 'YUYV' # V4L2_PIX_FMT_YUV422P : 7 '422P' # V4L2_PIX_FMT_YUV420 : 8 'YU12' ; v4l2_palette 8 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
