From: Lad, Prabhakar prabhakar@ti.com
add V4L2_CID_DPCM_PREDICTOR control of type menu, which
determines the dpcm predictor. The predictor can be either
simple or advanced.
Signed-off-by: Lad, Prabhakar prabhakar@ti.com
Signed-off-by: Manjunath Hadli manjunath.ha...@ti.com
Acked-by: Hans Verkuil hans.verk...@cisco.com
Reviewed-by: Sylwester Nawrocki s.nawro...@samsung.com
Cc: Sakari Ailus sakari.ai...@iki.fi
Cc: Laurent Pinchart laurent.pinch...@ideasonboard.com
Cc: Mauro Carvalho Chehab mche...@infradead.org
Cc: Hans de Goede hdego...@redhat.com
Cc: Kyungmin Park kyungmin.p...@samsung.com
Cc: Rob Landley r...@landley.net
---
This patches has one checkpatch warning for line over
80 characters altough it can be avoided I have kept it
for consistency.
Changes for v5:
1: Changed the control's name to 'Simple' and 'Advanced'
as pointed by Sakari.
2: Changed the description of DPCM. Thanks to Sakari for
providing the description.
Changes for v4:
1: Aligned the description to fit appropriately in the
para tag, pointed by Sylwester.
Changes for v3:
1: Added better explanation for DPCM, pointed by Hans.
Changes for v2:
1: Added documentaion in controls.xml pointed by Sylwester.
2: Chnaged V4L2_DPCM_PREDICTOR_ADVANCE to V4L2_DPCM_PREDICTOR_ADVANCED
pointed by Sakari.
Documentation/DocBook/media/v4l/controls.xml | 39 +-
drivers/media/v4l2-core/v4l2-ctrls.c |9 ++
include/linux/videodev2.h|5 +++
3 files changed, 52 insertions(+), 1 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/controls.xml
b/Documentation/DocBook/media/v4l/controls.xml
index 93b9c68..2c1599f 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -4267,7 +4267,44 @@ interface and may change in the future./para
pixels / second.
/entry
/row
- rowentry/entry/row
+ row
+ entry
spanname=idconstantV4L2_CID_DPCM_PREDICTOR/constant/entry
+ entrymenu/entry
+ /row
+ row id=v4l2-dpcm-predictor
+ entry spanname=descr Differential pulse-code modulation (DPCM)
compression can
+ be used to compress the samples into fewer bits than they would
otherwise require.
+ This is done by calculating the difference between consecutive
samples and outputting
+ the difference which in average is much smaller than the values of
the samples
+ themselves since there is generally lots of correlation between
adjacent pixels. In
+ decompression the original samples are reconstructed. The process
isn't lossless as
+ the encoded sample size in bits is less than the original.
+
+ paraFormats using DPCM compression include xref
linkend=pixfmt-srggb10dpcm8 /./para
+
+ paraThis control is used to select the predictor used to encode
the samples./para
+
+ paraThe main difference between the simple and the advanced
predictors is image quality,
+ with advanced predictor supposed to produce better quality images
as a result. Simple
+ predictor can be used e.g. for testing purposes. For more
information about DPCM see ulink
+
url=http://en.wikipedia.org/wiki/Differential_pulse-code_modulation;Wikipedia/ulink./para
+ /entry
+ /row
+ row
+ entrytbl spanname=descr cols=2
+ tbody valign=top
+ row
+entryconstantV4L2_DPCM_PREDICTOR_SIMPLE/constant/entry
+ entryPredictor type is simple/entry
+ /row
+ row
+
entryconstantV4L2_DPCM_PREDICTOR_ADVANCED/constant/entry
+ entryPredictor type is advanced/entry
+ /row
+ /tbody
+ /entrytbl
+ /row
+ rowentry/entry/row
/tbody
/tgroup
/table
diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c
b/drivers/media/v4l2-core/v4l2-ctrls.c
index b6a2ee7..8f2f40b 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -425,6 +425,11 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
Gray,
NULL,
};
+ static const char * const dpcm_predictor[] = {
+ Simple,
+ Advanced,
+ NULL,
+ };
switch (id) {
case V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ:
@@ -502,6 +507,8 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
return mpeg4_profile;
case V4L2_CID_JPEG_CHROMA_SUBSAMPLING:
return jpeg_chroma_subsampling;
+ case V4L2_CID_DPCM_PREDICTOR:
+ return dpcm_predictor;
default:
return NULL;
@@ -732,6 +739,7 @@ const char *v4l2_ctrl_get_name(u32 id)
case V4L2_CID_IMAGE_PROC_CLASS: return Image Processing
Controls;
case
