On 09/03/2012 09:20 AM, Prabhakar Lad wrote: > From: Lad, Prabhakar <prabhakar.lad@xxxxxx> > > 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@xxxxxx> > Signed-off-by: Manjunath Hadli <manjunath.hadli@xxxxxx> > Cc: Sakari Ailus <sakari.ailus@xxxxxx> > Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx> > Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx> > Cc: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx> > Cc: Hans de Goede <hdegoede@xxxxxxxxxx> > Cc: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> > Cc: Rob Landley <rob@xxxxxxxxxxx> > Cc: HeungJun Kim <riverful.kim@xxxxxxxxxxx> Looks good. Reviewed-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
