question about how v4l2src gets supported capture device formats

[Chuck Crisler]

Thank you. Where can I find this library, or a tarball of the source?

On Mon, Feb 4, 2013 at 4:24 PM, Tim-Philipp Müller <t.i.m at zen.co.uk> wrote:

> On Mon, 2013-02-04 at 16:09 -0500, Chuck Crisler wrote:
>
> > I am working with a Sensoray hardware capture device and encoder. I am
> > trying to extend v4l2src to allow me to specify some of the hardware
> > modes. I am working with plugins-good v. 0.10.25. The version of the
> > libgstvideo4linux2 that was pre-built (I think I got it from
> > RPM_FUSION) gets 15 formats, which includes the 12 that the
> > VIDIOC_ENUM_FMT ioctl call returns plus 3 others. The version of code
> > that I built (and v4l2-ctl --list-formats) only gets the base 12
> > formats. The source code breaks out of the 'get' loop when the
> > v4l2_ioctl call returns < 0. It simply increments the format index for
> > each iteration. I am not changing the driver between runs when I
> > change the v4l2src library from the pre-built to my version. How can
> > the pre-built library version get the additional formats? In my
> > version of the source code there aren't any '#ifdef...' in this area
> > and the line numbers for the pre-built library match the line numbers
> > of the source, which I got here. The additional formats include: RGB3,
> > YU12, YV12.
> >
> > I thank you if you can restore my sanity! (I appreciate all help
> > anyway.)
>
> There's a little helper library called libv4l2/libv4lconvert that does
> conversions for more (or less) 'exotic' formats under the hood. The
> GStreamer video4linux2 plugin can be built against that lib (then all
> ioctls are replaced with function calls into that lib) or not. I suspect
> when you build you don't link against it, while the prebuilt version
> does.
>
> Cheers
>  -Tim
>
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