Hi! > > > > mplayer is useful for testing... but that one already works (after you > > > > setup the pipeline, and configure exposure/gain). > > > > > > > > But thats useful for testing, not really for production. Image will be > > > > out of focus and with wrong white balance. > > > > > > > > What I would really like is an application to get still photos. For > > > > taking pictures with manual settings we need > > > > > > > > a) units for controls: user wants to focus on 1m, and take picture > > > > with ISO200, 1/125 sec. We should also tell him that lens is f/5.6 and > > > > focal length is 20mm with 5mm chip. > > > > > > > > But... autofocus/autogain would really be good to have. Thus we need: > > > > > > > > b) for each frame, we need exposure settings and focus position at > > > > time frame was taken. Otherwise autofocus/autogain will be too > > > > slow. At least focus position is going to be tricky -- either kernel > > > > would have to compute focus position for us (not trivial) or we'd need > > > > enough information to compute it in userspace. > > > > > > > > There are more problems: hardware-accelerated preview is not trivial > > > > to set up (and I'm unsure if it can be done in generic way). Still > > > > photos application needs to switch resolutions between preview and > > > > photo capture. Probably hardware-accelerated histograms are needed for > > > > white balance, auto gain and auto focus, .... > > > > > > > > It seems like there's a _lot_ of stuff to be done before we have > > > > useful support for complex cameras... > > > > > > Taking still pictures using a hardware-accelerated preview is > > > a sophisticated use case. I don't know any userspace application > > > that does that. Ok, several allow taking snapshots, by simply > > > storing the image of the current frame. > > > > Well, there are applications that take still pictures. Android has > > one. Maemo has another. Then there's fcam-dev. Its open source; with > > modified kernel it is fully usable. I have version that runs on recent > > nearly-mainline on N900. > > Hmm... it seems that FCam is specific for N900: > http://fcam.garage.maemo.org/ > > If so, then we have here just the opposite problem, if want it to be > used as a generic application, as very likely it requires OMAP3-specific > graph/subdevs. Well... there's quick and great version on maemo.org. I do have local version (still somehow N900-specific), but it no longer uses hardware histogram/sharpness support. Should be almost generic. > > So yes, I'd like solution for problems a) and b). ...but it has camera parameters hardcoded (problem a) and slow (problem b). > > Question is if camera without autofocus is usable. I'd say "not > > really".qv4l2 > > That actually depends on the sensor and how focus is adjusted. > > I'm testing right now this camera module for RPi: > https://www.raspberrypi.org/products/camera-module-v2/ > > I might be wrong, but this sensor doesn't seem to have auto-focus. > Instead, it seems to use a wide-angle lens. So, except when the > object is too close, the focus look OK. Well, cameras without autofocus are somehow usable without autofocus. But cameras with autofocus don't work too well without one. > > If we really want to go that way (is not modifying library to access > > the right files quite easy?), I believe non-confusing option would be > > to have '/dev/video0 -- omap3 camera for legacy applications' which > > would include all the controls. > > Yeah, keeping /dev/video0 reserved for generic applications is something > that could work. Not sure how easy would be to implement it. Plus advanced applications would just ignore /dev/video0.. and not be confused. > > > > > > You can get Nokia N900 on aliexpress. If not, they are still available > > > > between people :-) > > > > > > I have one. Unfortunately, I never had a chance to use it, as the display > > > stopped working one week after I get it. > > > > Well, I guess the easiest option is to just get another one :-). > > :-) Well, I guess very few units of N900 was sold in Brazil. Importing > one is too expensive, due to taxes. Try to ask at local mailing list. Those machines were quite common. > > But otoh -- N900 is quite usable without the screen. 0xffff tool can > > be used to boot the kernel, then you can use nfsroot and usb > > networking. It also has serial port (over strange > > connector). Connected over ssh over usb network is actually how I do > > most of the v4l work. > > If you pass me the pointers, I can try it when I have some time. Ok, I guess I'll do that in private email. > Anyway, I got myself an ISEE IGEPv2, with the expansion board: > https://www.isee.biz/products/igep-processor-boards/igepv2-dm3730 > https://www.isee.biz/products/igep-expansion-boards/igepv2-expansion > > The expansion board comes with a tvp5150 analog TV demod. So, with > this device, I can simply connect it to a composite input signal. > I have some sources here that I can use to test it. Well... it looks like TV capture is a "solved" problem. Taking useful photos is what is hard... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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