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``
+ - 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",
+ 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
