* [PATCH v3] media: v4l2-ctrls: add control for dpcm predictor
@ 2012-09-03 7:20 Prabhakar Lad
2012-09-03 9:05 ` Hans Verkuil
2012-09-03 9:21 ` Sylwester Nawrocki
0 siblings, 2 replies; 4+ messages in thread
From: Prabhakar Lad @ 2012-09-03 7:20 UTC (permalink / raw)
To: LMML
Cc: dlos, linux-kernel, Manjunath Hadli, Laurent Pinchart, linux-doc,
Lad, Prabhakar, Sakari Ailus, Hans Verkuil,
Mauro Carvalho Chehab, Sylwester Nawrocki, Hans de Goede,
Kyungmin Park, Rob Landley, HeungJun Kim
From: Lad, Prabhakar <prabhakar.lad@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.lad@ti.com>
Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Rob Landley <rob@landley.net>
Cc: HeungJun Kim <riverful.kim@samsung.com>
---
This patches has one checkpatch warning for line over
80 characters altough it can be avoided I have kept it
for consistency.
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 | 48 +++++++++++++++++++++++++-
drivers/media/v4l2-core/v4l2-ctrls.c | 9 +++++
include/linux/videodev2.h | 5 +++
3 files changed, 61 insertions(+), 1 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index 93b9c68..f704218 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -4267,7 +4267,53 @@ 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) is a signal
+ encoder that uses the baseline of pulse-code modulation (PCM) but adds some
+ functionalities based on the prediction of the samples of the signal. The input
+ can be an analog signal or a digital signal.
+
+ <para>If the input is a continuous-time
+ analog signal, it needs to be sampled first so that a discrete-time signal is
+ the input to the DPCM encoder.</para>
+
+ <para>Simple: take the values of two
+ consecutive samples; if they are analog samples, quantize them; calculate the
+ difference between the first one and the next; the output is the difference, and
+ it can be further entropy coded.</para>
+
+ <para>Advanced: instead of taking a difference relative to a previous input sample,
+ take the difference relative to the output of a local model of the decoder process;
+ in this option, the difference can be quantized, which allows a good way to
+ incorporate a controlled loss in the encoding.</para>
+
+ <para>Applying one of these two processes, short-term redundancy (positive correlation of
+ nearby values) of the signal is eliminated; compression ratios on the order of 2 to 4
+ can be achieved if differences are subsequently entropy coded, because the entropy of
+ the difference signal is much smaller than that of the original discrete signal treated
+ as independent samples.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..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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v3] media: v4l2-ctrls: add control for dpcm predictor
2012-09-03 7:20 [PATCH v3] media: v4l2-ctrls: add control for dpcm predictor Prabhakar Lad
@ 2012-09-03 9:05 ` Hans Verkuil
2012-09-03 9:21 ` Sylwester Nawrocki
1 sibling, 0 replies; 4+ messages in thread
From: Hans Verkuil @ 2012-09-03 9:05 UTC (permalink / raw)
To: Prabhakar Lad
Cc: LMML, dlos, linux-kernel, Manjunath Hadli, Laurent Pinchart,
linux-doc, Sakari Ailus, Hans Verkuil, Mauro Carvalho Chehab,
Sylwester Nawrocki, Hans de Goede, Kyungmin Park, Rob Landley,
HeungJun Kim
On Mon September 3 2012 09:20:51 Prabhakar Lad wrote:
> From: Lad, Prabhakar <prabhakar.lad@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.lad@ti.com>
> Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
> Cc: Sakari Ailus <sakari.ailus@iki.fi>
> Cc: Hans Verkuil <hans.verkuil@cisco.com>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
> Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Rob Landley <rob@landley.net>
> Cc: HeungJun Kim <riverful.kim@samsung.com>
> ---
> This patches has one checkpatch warning for line over
> 80 characters altough it can be avoided I have kept it
> for consistency.
>
> Changes for v3:
> 1: Added better explanation for DPCM, pointed by Hans.
Much better!
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Regards,
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 | 48 +++++++++++++++++++++++++-
> drivers/media/v4l2-core/v4l2-ctrls.c | 9 +++++
> include/linux/videodev2.h | 5 +++
> 3 files changed, 61 insertions(+), 1 deletions(-)
>
> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
> index 93b9c68..f704218 100644
> --- a/Documentation/DocBook/media/v4l/controls.xml
> +++ b/Documentation/DocBook/media/v4l/controls.xml
> @@ -4267,7 +4267,53 @@ 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) is a signal
> + encoder that uses the baseline of pulse-code modulation (PCM) but adds some
> + functionalities based on the prediction of the samples of the signal. The input
> + can be an analog signal or a digital signal.
> +
> + <para>If the input is a continuous-time
> + analog signal, it needs to be sampled first so that a discrete-time signal is
> + the input to the DPCM encoder.</para>
> +
> + <para>Simple: take the values of two
> + consecutive samples; if they are analog samples, quantize them; calculate the
> + difference between the first one and the next; the output is the difference, and
> + it can be further entropy coded.</para>
> +
> + <para>Advanced: instead of taking a difference relative to a previous input sample,
> + take the difference relative to the output of a local model of the decoder process;
> + in this option, the difference can be quantized, which allows a good way to
> + incorporate a controlled loss in the encoding.</para>
> +
> + <para>Applying one of these two processes, short-term redundancy (positive correlation of
> + nearby values) of the signal is eliminated; compression ratios on the order of 2 to 4
> + can be achieved if differences are subsequently entropy coded, because the entropy of
> + the difference signal is much smaller than that of the original discrete signal treated
> + as independent samples.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..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
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3] media: v4l2-ctrls: add control for dpcm predictor
2012-09-03 7:20 [PATCH v3] media: v4l2-ctrls: add control for dpcm predictor Prabhakar Lad
2012-09-03 9:05 ` Hans Verkuil
@ 2012-09-03 9:21 ` Sylwester Nawrocki
2012-09-03 9:37 ` Prabhakar Lad
1 sibling, 1 reply; 4+ messages in thread
From: Sylwester Nawrocki @ 2012-09-03 9:21 UTC (permalink / raw)
To: Prabhakar Lad
Cc: LMML, dlos, linux-kernel, Manjunath Hadli, Laurent Pinchart,
linux-doc, Sakari Ailus, Hans Verkuil, Mauro Carvalho Chehab,
Hans de Goede, Kyungmin Park, Rob Landley
On 09/03/2012 09:20 AM, Prabhakar Lad wrote:
> From: Lad, Prabhakar <prabhakar.lad@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.lad@ti.com>
> Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
> Cc: Sakari Ailus <sakari.ailus@iki.fi>
> Cc: Hans Verkuil <hans.verkuil@cisco.com>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
> Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Rob Landley <rob@landley.net>
> Cc: HeungJun Kim <riverful.kim@samsung.com>
Looks good.
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
> ---
> This patches has one checkpatch warning for line over
> 80 characters altough it can be avoided I have kept it
> for consistency.
>
> 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 | 48 +++++++++++++++++++++++++-
> drivers/media/v4l2-core/v4l2-ctrls.c | 9 +++++
> include/linux/videodev2.h | 5 +++
> 3 files changed, 61 insertions(+), 1 deletions(-)
>
> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
> index 93b9c68..f704218 100644
> --- a/Documentation/DocBook/media/v4l/controls.xml
> +++ b/Documentation/DocBook/media/v4l/controls.xml
> @@ -4267,7 +4267,53 @@ 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) is a signal
> + encoder that uses the baseline of pulse-code modulation (PCM) but adds some
> + functionalities based on the prediction of the samples of the signal. The input
> + can be an analog signal or a digital signal.
> +
> + <para>If the input is a continuous-time
> + analog signal, it needs to be sampled first so that a discrete-time signal is
> + the input to the DPCM encoder.</para>
nit: this whole paragraph could fit in 2 lines.
> +
> + <para>Simple: take the values of two
> + consecutive samples; if they are analog samples, quantize them; calculate the
> + difference between the first one and the next; the output is the difference, and
> + it can be further entropy coded.</para>
> +
> + <para>Advanced: instead of taking a difference relative to a previous input sample,
> + take the difference relative to the output of a local model of the decoder process;
> + in this option, the difference can be quantized, which allows a good way to
> + incorporate a controlled loss in the encoding.</para>
> +
> + <para>Applying one of these two processes, short-term redundancy (positive correlation of
> + nearby values) of the signal is eliminated; compression ratios on the order of 2 to 4
> + can be achieved if differences are subsequently entropy coded, because the entropy of
> + the difference signal is much smaller than that of the original discrete signal treated
> + as independent samples.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..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
Regards,
Sylwester
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3] media: v4l2-ctrls: add control for dpcm predictor
2012-09-03 9:21 ` Sylwester Nawrocki
@ 2012-09-03 9:37 ` Prabhakar Lad
0 siblings, 0 replies; 4+ messages in thread
From: Prabhakar Lad @ 2012-09-03 9:37 UTC (permalink / raw)
To: Sylwester Nawrocki
Cc: LMML, dlos, linux-kernel, Manjunath Hadli, Laurent Pinchart,
linux-doc, Sakari Ailus, Hans Verkuil, Mauro Carvalho Chehab,
Hans de Goede, Kyungmin Park, Rob Landley
Hi Sylwester,
Thanks for the review.
On Monday 03 September 2012 02:51 PM, Sylwester Nawrocki wrote:
> On 09/03/2012 09:20 AM, Prabhakar Lad wrote:
>> From: Lad, Prabhakar <prabhakar.lad@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.lad@ti.com>
>> Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
>> Cc: Sakari Ailus <sakari.ailus@iki.fi>
>> Cc: Hans Verkuil <hans.verkuil@cisco.com>
>> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>> Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
>> Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
>> Cc: Hans de Goede <hdegoede@redhat.com>
>> Cc: Kyungmin Park <kyungmin.park@samsung.com>
>> Cc: Rob Landley <rob@landley.net>
>> Cc: HeungJun Kim <riverful.kim@samsung.com>
>
> Looks good.
>
> Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
>
>> ---
>> This patches has one checkpatch warning for line over
>> 80 characters altough it can be avoided I have kept it
>> for consistency.
>>
>> 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 | 48 +++++++++++++++++++++++++-
>> drivers/media/v4l2-core/v4l2-ctrls.c | 9 +++++
>> include/linux/videodev2.h | 5 +++
>> 3 files changed, 61 insertions(+), 1 deletions(-)
>>
>> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
>> index 93b9c68..f704218 100644
>> --- a/Documentation/DocBook/media/v4l/controls.xml
>> +++ b/Documentation/DocBook/media/v4l/controls.xml
>> @@ -4267,7 +4267,53 @@ 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) is a signal
>> + encoder that uses the baseline of pulse-code modulation (PCM) but adds some
>> + functionalities based on the prediction of the samples of the signal. The input
>> + can be an analog signal or a digital signal.
>> +
>> + <para>If the input is a continuous-time
>> + analog signal, it needs to be sampled first so that a discrete-time signal is
>> + the input to the DPCM encoder.</para>
>
> nit: this whole paragraph could fit in 2 lines.
>
thanks for the catch ,I'll post a v4 fixing this.
Thanks and Regards,
--Prabhakar Lad
>> +
>> + <para>Simple: take the values of two
>> + consecutive samples; if they are analog samples, quantize them; calculate the
>> + difference between the first one and the next; the output is the difference, and
>> + it can be further entropy coded.</para>
>> +
>> + <para>Advanced: instead of taking a difference relative to a previous input sample,
>> + take the difference relative to the output of a local model of the decoder process;
>> + in this option, the difference can be quantized, which allows a good way to
>> + incorporate a controlled loss in the encoding.</para>
>> +
>> + <para>Applying one of these two processes, short-term redundancy (positive correlation of
>> + nearby values) of the signal is eliminated; compression ratios on the order of 2 to 4
>> + can be achieved if differences are subsequently entropy coded, because the entropy of
>> + the difference signal is much smaller than that of the original discrete signal treated
>> + as independent samples.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..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
>
> Regards,
> Sylwester
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2012-09-03 7:20 [PATCH v3] media: v4l2-ctrls: add control for dpcm predictor Prabhakar Lad
2012-09-03 9:05 ` Hans Verkuil
2012-09-03 9:21 ` Sylwester Nawrocki
2012-09-03 9:37 ` Prabhakar Lad
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