On Thursday 29 January 2009 22:59:13 Trent Piepho wrote:
> On Thu, 29 Jan 2009, Hans Verkuil wrote:
> > On Thursday 29 January 2009 08:44:20 DongSoo Kim wrote:
> > > Hello.
> > >
> > > > +#define VIDIOC_S_COLOR_SPACE_CONV _IOW('V', 83, struct
> > > > v4l2_color_space_conversion) +#define VIDIOC_G_COLOR_SPACE_CONV
> > > > _IOR('V', 84, struct v4l2_color_space_conversion)
> > >
> > > Do you mind if I ask a question about those ioctls?
> > > Because as far as I understand, we can use VIDIOC_S_FMT ioctl to
> > > convert colorspaces. Setting through colorspace member in
> > > v4l2_pix_format, we could change output colorspace.
> >
> > Colorspace is read-only, you cannot set it. It just gives you the
> > colorspace that the hardware uses by default.
>
> Is there a reason it must be read-only?
The V4L2 spec. And I've no idea if we can safely change it to a read/write
property or if there are apps out their that do not set this field.
> > If you want to fully control the colorspace, then you need these
> > ioctls.
>
> I don't know about "fully". I don't see anything about gamma correction.
> Since there is no documentation, it's also not clear if it can describe
> the full range luma the bt848 and cx88 can produce.
I'm also waiting for full documentation on this. I do know that this type of
matrix is common in other devices as well.
I'm not sure if gamma correction can be done with CSC, but I think that
should be done through a separate control anyway. However, I'm no expert.
Regards,
Hans
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG
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