[v5] media: v4l2-ctrls: add control for dpcm predictor

Commit Message

Prabhakar Lad Sept. 10, 2012, 5:57 a.m. UTC

From: Lad, Prabhakar <[e-mail]>

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 <[e-mail]>
Signed-off-by: Manjunath Hadli <[e-mail]>
Acked-by: Hans Verkuil <[e-mail]>
Reviewed-by: Sylwester Nawrocki <[e-mail]>
Cc: Sakari Ailus <[e-mail]>
Cc: Laurent Pinchart <[e-mail]>
Cc: Mauro Carvalho Chehab <[e-mail]>
Cc: Hans de Goede <[e-mail]>
Cc: Kyungmin Park <[e-mail]>
Cc: Rob Landley <[e-mail]>
---
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(-)

Comments

Sakari Ailus Sept. 10, 2012, 7:32 a.m. UTC | #1

Hi Prabhakar,

On Mon, Sep 10, 2012 at 11:27:55AM +0530, Prabhakar Lad wrote:
...
> +	  <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.
> +
> +	    <para>Formats using DPCM compression include <xref linkend="pixfmt-srggb10dpcm8" />.</para>
> +
> +	    <para>This control is used to select the predictor used to encode the samples.</para>
> +
> +	    <para>The 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>

Could you fit the above text (description of the control) at 80 characters
per line? With that change,

Acked-by: Sakari Ailus <[e-mail]>

Kind regards,

Patch

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>
-	  <row><entry></entry></row>
+	  <row>
+	    <entry spanname="id"><constant>V4L2_CID_DPCM_PREDICTOR</constant></entry>
+	    <entry>menu</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.
+
+	    <para>Formats using DPCM compression include <xref linkend="pixfmt-srggb10dpcm8" />.</para>
+
+	    <para>This control is used to select the predictor used to encode the samples.</para>
+
+	    <para>The 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>
+	         <entry><constant>V4L2_DPCM_PREDICTOR_SIMPLE</constant></entry>
+	          <entry>Predictor type is simple</entry>
+	        </row>
+	        <row>
+	          <entry><constant>V4L2_DPCM_PREDICTOR_ADVANCED</constant></entry>
+	          <entry>Predictor type is advanced</entry>
+	        </row>
+	      </tbody>
+	    </entrytbl>
+	  </row>
+	<row><entry></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 V4L2_CID_LINK_FREQ:		return "Link Frequency";
 	case V4L2_CID_PIXEL_RATE:		return "Pixel Rate";
+	case V4L2_CID_DPCM_PREDICTOR:		return "DPCM Predictor";
 
 	default:
 		return NULL;
@@ -832,6 +840,7 @@  void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
 	case V4L2_CID_ISO_SENSITIVITY_AUTO:
 	case V4L2_CID_EXPOSURE_METERING:
 	case V4L2_CID_SCENE_MODE:
+	case V4L2_CID_DPCM_PREDICTOR:
 		*type = V4L2_CTRL_TYPE_MENU;
 		break;
 	case V4L2_CID_LINK_FREQ:
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 6d6dfa7..ca9fb78 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -2000,6 +2000,11 @@  enum v4l2_jpeg_chroma_subsampling {
 
 #define V4L2_CID_LINK_FREQ			(V4L2_CID_IMAGE_PROC_CLASS_BASE + 1)
 #define V4L2_CID_PIXEL_RATE			(V4L2_CID_IMAGE_PROC_CLASS_BASE + 2)
+#define V4L2_CID_DPCM_PREDICTOR			(V4L2_CID_IMAGE_PROC_CLASS_BASE + 3)
+enum v4l2_dpcm_predictor {
+	V4L2_DPCM_PREDICTOR_SIMPLE	= 0,
+	V4L2_DPCM_PREDICTOR_ADVANCED	= 1,
+};
 
 /*
  *	T U N I N G