From: Lad, Prabhakar <[email protected]>
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 <[email protected]>
Signed-off-by: Manjunath Hadli <[email protected]>
Cc: Sakari Ailus <[email protected]>
Cc: Hans Verkuil <[email protected]>
Cc: Laurent Pinchart <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Sylwester Nawrocki <[email protected]>
Cc: Hans de Goede <[email protected]>
Cc: Kyungmin Park <[email protected]>
---
This patches has one checkpatch warning for line over
80 characters altough it can be avoided I have kept it
for consistency.
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 | 25 ++++++++++++++++++++++++-
drivers/media/v4l2-core/v4l2-ctrls.c | 9 +++++++++
include/linux/videodev2.h | 5 +++++
3 files changed, 38 insertions(+), 1 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index 93b9c68..84746d0 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -4267,7 +4267,30 @@ 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"> DPCM Predictor: depicts what type of prediction
+ is used simple or advanced.
+ </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..2d7bc15 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 Predictor",
+ "Advanced Predictor",
+ 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
--
1.7.0.4
Hi Prabhakar!
I've got some documentation review comments below...
On Thu August 30 2012 00:58:16 Prabhakar Lad wrote:
> From: Lad, Prabhakar <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Manjunath Hadli <[email protected]>
> Cc: Sakari Ailus <[email protected]>
> Cc: Hans Verkuil <[email protected]>
> Cc: Laurent Pinchart <[email protected]>
> Cc: Mauro Carvalho Chehab <[email protected]>
> Cc: Sylwester Nawrocki <[email protected]>
> Cc: Hans de Goede <[email protected]>
> Cc: Kyungmin Park <[email protected]>
> ---
> This patches has one checkpatch warning for line over
> 80 characters altough it can be avoided I have kept it
> for consistency.
>
> 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 | 25 ++++++++++++++++++++++++-
> drivers/media/v4l2-core/v4l2-ctrls.c | 9 +++++++++
> include/linux/videodev2.h | 5 +++++
> 3 files changed, 38 insertions(+), 1 deletions(-)
>
> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
> index 93b9c68..84746d0 100644
> --- a/Documentation/DocBook/media/v4l/controls.xml
> +++ b/Documentation/DocBook/media/v4l/controls.xml
> @@ -4267,7 +4267,30 @@ 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"> DPCM Predictor: depicts what type of prediction
> + is used simple or advanced.
This is not useful information. It basically just rephrases the name of the
define without actually telling me anything.
I would expect to see here at least the following:
- what the DPCM abbreviation stands for
- a link or bibliography reference to the relevant standard (if there is any)
- a high-level explanation of what this do and what the difference is between
simple and advanced.
If this is part of a video compression standard, then this control would probably
belong to the MPEG control class as well.
Regards,
Hans
> + </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..2d7bc15 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 Predictor",
> + "Advanced Predictor",
> + 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
>
Hi Hans and Prabhakar,
Hans Verkuil wrote:
> Hi Prabhakar!
>
> I've got some documentation review comments below...
>
> On Thu August 30 2012 00:58:16 Prabhakar Lad wrote:
>> From: Lad, Prabhakar <[email protected]>
>>
>> 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 <[email protected]>
>> Signed-off-by: Manjunath Hadli <[email protected]>
>> Cc: Sakari Ailus <[email protected]>
>> Cc: Hans Verkuil <[email protected]>
>> Cc: Laurent Pinchart <[email protected]>
>> Cc: Mauro Carvalho Chehab <[email protected]>
>> Cc: Sylwester Nawrocki <[email protected]>
>> Cc: Hans de Goede <[email protected]>
>> Cc: Kyungmin Park <[email protected]>
>> ---
>> This patches has one checkpatch warning for line over
>> 80 characters altough it can be avoided I have kept it
>> for consistency.
>>
>> 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 | 25 ++++++++++++++++++++++++-
>> drivers/media/v4l2-core/v4l2-ctrls.c | 9 +++++++++
>> include/linux/videodev2.h | 5 +++++
>> 3 files changed, 38 insertions(+), 1 deletions(-)
>>
>> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
>> index 93b9c68..84746d0 100644
>> --- a/Documentation/DocBook/media/v4l/controls.xml
>> +++ b/Documentation/DocBook/media/v4l/controls.xml
>> @@ -4267,7 +4267,30 @@ 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"> DPCM Predictor: depicts what type of prediction
>> + is used simple or advanced.
>
> This is not useful information. It basically just rephrases the name of the
> define without actually telling me anything.
>
> I would expect to see here at least the following:
>
> - what the DPCM abbreviation stands for
> - a link or bibliography reference to the relevant standard (if there is any)
There's a Wikipedia article:
<URL:http://en.wikipedia.org/wiki/Differential_pulse-code_modulation>
It's the same DPCM encoding as in many of the compressed raw bayer formats.
> - a high-level explanation of what this do and what the difference is between
> simple and advanced.
That's somewhat subjective and hardware dependent. If I understand this
correctly, the "advanced" should differ only quality-wise from "simple"
option. Why one would use "simple" instead of "advanced" then? Perhaps
mostly for testing purposes; it might be that the advanced predictor
could have issues in certain cases where the simple would not. However
this isn't the only piece of hardware where I see that this is
configurable, and the simple one was even the default.
> If this is part of a video compression standard, then this control would probably
> belong to the MPEG control class as well.
It's not --- DPCM compression is typically used on the bus between the
sensor and the receiver to compress the data as the bus is often a
limiting factor in the transfer rate. DPCM compression can be used to
squeeze the data from 10 to 8 bits without much loss in quality or
dynamic range.
Cheers,
--
Sakari Ailus
[email protected]