Hi Hans,
On Fri, Sep 06, 2024 at 07:44:05AM +0200, Hans Verkuil wrote:
> On 06/09/2024 00:53, Laurent Pinchart wrote:
> > Companding refers to compression and expansion of pixel data to fit in a
> > smaller range. The control is named V4L2_CID_COMPANDING, and only
> > supports compression initially.
> >
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > ---
> > Changes since v1:
> >
> > - Rename V4L2_COMPANDING_ALAW to V4L2_COMPANDING_COMPRESS
> > - Document V4L2_COMPANDING_LINEAR and V4L2_COMPANDING_COMPRESS
> > ---
> > .../media/v4l/ext-ctrls-image-process.rst | 16 ++++++++++++++++
> > drivers/media/v4l2-core/v4l2-ctrls-defs.c | 9 +++++++++
> > include/uapi/linux/v4l2-controls.h | 5 +++++
> > 3 files changed, 30 insertions(+)
> >
> > diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
> > index b1c2ab2854af..d529b0a8cd41 100644
> > --- a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
> > +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
> > @@ -55,3 +55,19 @@ Image Process Control IDs
> > control value divided by e.g. 0x100, meaning that to get no
> > digital gain the control value needs to be 0x100. The no-gain
> > configuration is also typically the default.
> > +
> > +``V4L2_CID_COMPANDING (menu)``
> > + Companding refers to compression and expansion of pixel data to fit in a
> > + smaller range.
> > +
> > +
> > +.. tabularcolumns:: |p{5.7cm}|p{11.8cm}|
> > +
> > +.. flat-table::
> > + :header-rows: 0
> > + :stub-columns: 0
> > +
> > + * - ``V4L2_COMPANDING_LINEAR``
> > + - No companding.
> > + * - ``V4L2_COMPANDING_COMPRESS``
>
> It's weird that this is called 'COMPRESS',
>
> > + - Compress the data using a device-specific curve.
> > diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> > index 1ea52011247a..841e415a88ae 100644
> > --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> > +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> > @@ -611,6 +611,11 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
> > "Cyclic",
> > NULL,
> > };
> > + static const char * const companding[] = {
> > + "Linear",
> > + "A-Law",
>
> but it is called 'A-Law' here. I think the same name should be used for both
> as this is confusing.
I forgot to change this. I'll use "Compress".
> > + NULL
> > + };
> >
> > switch (id) {
> > case V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ:
> > @@ -750,6 +755,8 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
> > return camera_orientation;
> > case V4L2_CID_MPEG_VIDEO_INTRA_REFRESH_PERIOD_TYPE:
> > return intra_refresh_period_type;
> > + case V4L2_CID_COMPANDING:
> > + return companding;
> > default:
> > return NULL;
> > }
> > @@ -1164,6 +1171,7 @@ const char *v4l2_ctrl_get_name(u32 id)
> > case V4L2_CID_TEST_PATTERN: return "Test Pattern";
> > case V4L2_CID_DEINTERLACING_MODE: return "Deinterlacing Mode";
> > case V4L2_CID_DIGITAL_GAIN: return "Digital Gain";
> > + case V4L2_CID_COMPANDING: return "Companding";
> >
> > /* DV controls */
> > /* Keep the order of the 'case's the same as in v4l2-controls.h! */
> > @@ -1421,6 +1429,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
> > case V4L2_CID_CAMERA_ORIENTATION:
> > case V4L2_CID_MPEG_VIDEO_INTRA_REFRESH_PERIOD_TYPE:
> > case V4L2_CID_HDR_SENSOR_MODE:
> > + case V4L2_CID_COMPANDING:
> > *type = V4L2_CTRL_TYPE_MENU;
> > break;
> > case V4L2_CID_LINK_FREQ:
> > diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> > index 974fd254e573..ca9e25f72886 100644
> > --- a/include/uapi/linux/v4l2-controls.h
> > +++ b/include/uapi/linux/v4l2-controls.h
> > @@ -1225,6 +1225,11 @@ enum v4l2_jpeg_chroma_subsampling {
> > #define V4L2_CID_TEST_PATTERN (V4L2_CID_IMAGE_PROC_CLASS_BASE + 3)
> > #define V4L2_CID_DEINTERLACING_MODE (V4L2_CID_IMAGE_PROC_CLASS_BASE + 4)
> > #define V4L2_CID_DIGITAL_GAIN (V4L2_CID_IMAGE_PROC_CLASS_BASE + 5)
> > +#define V4L2_CID_COMPANDING (V4L2_CID_IMAGE_PROC_CLASS_BASE + 6)
> > +enum v4l2_companding {
> > + V4L2_COMPANDING_LINEAR = 0,
> > + V4L2_COMPANDING_COMPRESS = 1,
> > +};
> >
> > /* DV-class control IDs defined by V4L2 */
> > #define V4L2_CID_DV_CLASS_BASE (V4L2_CTRL_CLASS_DV | 0x900)
--
Regards,
Laurent Pinchart
