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 <[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]> >> Cc: Rob Landley <[email protected]> >> Cc: HeungJun Kim <[email protected]> > > Looks good. > > Reviewed-by: Sylwester Nawrocki <[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 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
