Am Mittwoch, den 29.04.2009, 18:33 -0500 schrieb Theodore Kilgore:
>
> On Wed, 29 Apr 2009, hermann pitton wrote:
>
> > Hi,
> >
> > Am Mittwoch, den 29.04.2009, 15:31 -0400 schrieb Devin Heitmueller:
> >> On Wed, Apr 29, 2009 at 3:22 PM, Robin van Kleeff
> >> <robinvankleeff@xxxxxxxxx> wrote:
> >>> Hey everybody,
> >>>
> >>> I have been searching for information on using compact photo cameras
> >>> as video devices (and also for compatibility with gphoto through the
> >>> gphoto websites/mailing list).
> >>>
> >>> I was wondering if any of you knows which cameras (brand, type) I
> >>> should focus on? I'm interested in digital compact camera that can be
> >>> used to take decent quality pictures, and also function as for
> >>> instance a web cam for applications such as Ekiga. I am unable to
> >>> find any lists of cameras that are supported.
> >>>
> >>> By the way, I am much more an end-user then a developer, so forgive me
> >>> if I ask dumb questions, or if I ask questions that are outside of the
> >>> scope of this mailing list.
> >>>
> >>> Thanks in advance!
> >>>
> >>> Robin
> >>
> >> Hello Robin,
> >>
> >> Do you know of any such devices that claim to work like that even
> >> under Windows? Generally, all the digital cameras I see that can
> >> capture video can't do it while the device is plugged in to the PC.
> >> If you can provide some specific examples of models that do this under
> >> Windows, we can possibly look at what would be required to make them
> >> work under Linux.
> >>
> >> Cheers,
> >>
> >> Devin
> >>
> >
> > never cared much about it, but I was the opposite opinion.
> >
> > If it has Composite or S-Video and audio out it should simply work I
> > thought when plugged into the inputs of any capture card, also when
> > switched into video mode.
> >
> > I tested it once on a cheapo Jenoptik 6.0z3 MPEG4 and don't remember any
> > problems using an saa7131e Asus P7131 Dual with tvtime on Composite.
> >
> > In that case it is not registered as storage device at all.
> >
> > Cheers,
> > Hermann
>
> Ah. I was a little bit slow. Now I see what was behind the statement that
>
> "Generally, all the digital cameras I see that can capture video can't do
> it while the device is plugged in to the PC."
>
> So, for the original poster, here is (sort of) what is behind these
> comments:
>
> 1. Lots of still cameras, especially some of the really fancy ones are
> Mass Storage devices. To use a still camera which is a Mass Storage
> device, one merely mounts it just like any external hard drive, or flash
> drive. If a camera is a Mass Storage device, it can not be addressed in
> any other mode. In particular, it can not stream. It is acting then like a
> hard drive, and hard drives do not stream. Hard drives are for copying
> files onto and off of, that kind of thing.
>
> 2. There do exist cameras which can be addressed in more than one mode. It
> is not unusual to have a camera which can be addressed as a Mass Storage
> device and also in PTP mode. Sorry, about PTP mode I only know that it
> exists, is supported in Linux under libgphoto2, and some others are doing
> that.
>
> 3. If a camera will do more than one mode (Mass Storage or PTP, Mass
> Storage or streaming, PTP or streaming, or all three, in case such a thing
> exists) then its mode would have to be set before one plugs it into the
> computer, using some kind of control menu on the camera. Then, when the
> camera is plugged to the computer it will either come up with a different
> USB Product number (see my previous post) or will come up in some kind of
> different mode which is made explicit to the computer.
>
> Incidentally, the way that a USB device tells the computer about such
> things is to answer a standard query as soon as it is hooked up. That
> standard query has certain fields for its response. The things which must
> be answered are such things as what the Vendor and Product numbers are, a
> revision number, whether or not the device supports any of the standard
> modes. For these, there are three-byte codes (for example, Class Mass
> Storage, Subclass Transparent SCSI, Protocol Bulk Transport is 0x08 0x06
> 0x50), and the catchall classification is is 0xff 0xff 0xff meaning Class
> Proprietary, Subclass Proprietary, Protocol Proprietary. As I said, every
> USB device must provide this information in a standard way, and every
> operating system needs to have said information in order to know what to
> do in order to support the hardware which has just been plugged in. The
> way that you can see all of this information in human-readable form in
> Linux is to run the command lsusb, or to look at the file
> /proc/bus/usb/devices (not present on all distros). There is also some
> further explanation about such things in /usr/src/linux/Documentation/usb.
>
> Sorry if the above is a digression, but it should explain to you what is
> going on, and in particular why a camera can not be simultaneously a
> streaming device and a mass storage device. Any given camera could in
> principle do both of these, but not at the same time. And it would be
> needed to set the camera up beforehand using the control features present
> on the camera itself, while it is not hooked to the computer, to run in
> one of those modes and not in the other when it is next hooked up.
>
> Of course, a device which is Proprietary, Proprietary, Proprietary can
> jolly well do whatever it wants. The computer has been warned. The
> operating system either has the required support for the given device
> installed, or it does not. There are lots of proprietary dual-mode
> cameras. Some of them are supported and work very well in Linux. Some are
> not well supported or do not work at all. The reason for that is, of
> course, we get usually no cooperation at all from the hardware vendors.
>
> For the reasons I described above, I suggested already that you should
> download the video4linux mcode, and probably also the libgphoto2 code.
> That way, you can search through the two source trees and look for matches
> and possibly come up with something which pleases you. Do understand that
> if you do this, though, you will be confined to cameras which are either
> PTP cameras or fully proprietary cameras. If a camera will act both as a
> Mass Storage camera and as a streaming device, then you will probably not
> catch it this way. Perhaps you can think of other ways to trap that
> information. So, sticking to just libgphoto2 and the kernel source, here
> is what I would try if I were you:
>
> 1. look at the list of cameras supported by the Gphoto project, at the
> project website, or run the gphoto2 --list-cameras command. See if you
> recognize any camera which looks interesting.
>
> 2. search the directory libgphoto2/camlibs for that camera, by name. For
> example, if you search for "Logitech Clicksmart 310" you will come up with
> a line, in libgphoto2/camlibs/clicksmart310/library.c which says
>
> {"Logitech Clicksmart 310", GP_DRIVER_STATUS_TESTING, 0x46d, 0x0900},
>
> which tells you that the USB Vendor number is 0x46d and the Product number
> is 0x0900. Perhaps the vendor number should have been listed as 0x046d
> (oops!). So if you search somewhere else for 0x46d and what is written is
> 0x046d instead you will come up with thin air. Be careful with things like
> that, also that you might need to search for 46D, as well.
>
> Thus, if you search linux/drivers/media/video/gspca using (for example)
>
> grep 0900 *
>
> you will come up with
>
> spca500.c: {USB_DEVICE(0x046d, 0x0900), .driver_info =
> LogitechClickSmart310},
>
> which informs you that the camera is supported both in libgphoto2 as a
> still camera and in the spca500 kernel driver for use in streaming mode.
>
> I do use this camera only by way of example. Its max resolution is
> 352x288, and probably you want a better camera. But you get the idea.
>
> As another example, if you have a "Pixie Princess Jelly-Soft" camera, you
> can search on the Gphoto website, or run the command
>
> gphoto2 --list-cameras and search the output for it, and find it. You will
> find a line which says
>
> {"Pixie Princess Jelly-Soft", GP_DRIVER_STATUS_EXPERIMENTAL,
> 0x2770, 0x905c},
>
> And then if you search for the Vendor number you will find in the gspca
> code
>
> kilgota@khayyam:~/linux/gspca/gspca-repo/linux/drivers/media/video/gspca$
> grep 2770 *
> sq905.c: {USB_DEVICE(0x2770, 0x9120)},
> sq905c.c: * The 0x2770:0x9050 cameras have max resolution of 320x240.
> sq905c.c: {USB_DEVICE(0x2770, 0x905c)},
> sq905c.c: {USB_DEVICE(0x2770, 0x9050)},
> sq905c.c: {USB_DEVICE(0x2770, 0x913d)},
> kilgota@khayyam:~/linux/gspca/gspca-repo/linux/drivers/media/video/gspca$
>
> so you have one match in the file sq905c.c for the product number, too.
> The camera is not otherwise listed by name in the kernel source (because
> the driver for it supports at least sixteen other known cameras), but in
> spite of its funny name and appearance and squishy, pink "jelly-soft"
> exterior it is a quite standard SQ905C camera and works in streaming mode,
> too.
>
> I hope this helps you find what you are looking for.
>
> Theodore Kilgore
Sorry,
I have half a bottle of a fine Rioja Rosado this time.
If you plug it into a supported capture card, and it has Composite
and/or S-Video and audio out, all the above does not matter at all.
Cheers,
Hermann
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
