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SubjectRe: [PATCH v2] [media] v4l: add I / P frame min max QP definitions
Hi Hans,

For I frame min QP, if global min QP is set, the QP choose algorithm
should meet both of them, hence QP will >=
max(V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP,
V4L2_CID_MPEG_VIDEO_H264_MIN_QP).
And this is also the same to the P frame and max QP.
I can add some description to describe this behavior in the document.

Thanks,
Fish


Hans Verkuil <hverkuil-cisco@xs4all.nl> 於 2019年1月30日 週三 下午3:57寫道:
>
> On 1/30/19 8:45 AM, Fish Lin wrote:
> > Add following V4L2 QP parameters for H.264:
> > * V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP
> > * V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP
> > * V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP
> > * V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP
> >
> > These controls will limit QP range for intra and inter frame,
> > provide more manual control to improve video encode quality.
>
> How will this interact with V4L2_CID_MPEG_VIDEO_H264_MIN/MAX_QP?
>
> Or are drivers supposed to have either V4L2_CID_MPEG_VIDEO_H264_MIN/MAX_QP
> or these new controls? If so, then that should be documented.
>
> Regards,
>
> Hans
>
> >
> > Signed-off-by: Fish Lin <linfish@google.com>
> > ---
> > Changelog since v1:
> > - Add description in document.
> >
> > .../media/uapi/v4l/extended-controls.rst | 16 ++++++++++++++++
> > drivers/media/v4l2-core/v4l2-ctrls.c | 4 ++++
> > include/uapi/linux/v4l2-controls.h | 6 ++++++
> > 3 files changed, 26 insertions(+)
> >
> > diff --git a/Documentation/media/uapi/v4l/extended-controls.rst b/Documentation/media/uapi/v4l/extended-controls.rst
> > index 286a2dd7ec36..f5989fad34f9 100644
> > --- a/Documentation/media/uapi/v4l/extended-controls.rst
> > +++ b/Documentation/media/uapi/v4l/extended-controls.rst
> > @@ -1214,6 +1214,22 @@ enum v4l2_mpeg_video_h264_entropy_mode -
> > Quantization parameter for an B frame for H264. Valid range: from 0
> > to 51.
> >
> > +``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP (integer)``
> > + Minimum quantization parameter for H264 I frame, to limit I frame
> > + quality in a range. Valid range: from 0 to 51.
> > +
> > +``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP (integer)``
> > + Maximum quantization parameter for H264 I frame, to limit I frame
> > + quality in a range. Valid range: from 0 to 51.
> > +
> > +``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP (integer)``
> > + Minimum quantization parameter for H264 P frame, to limit P frame
> > + quality in a range. Valid range: from 0 to 51.
> > +
> > +``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP (integer)``
> > + Maximum quantization parameter for H264 P frame, to limit P frame
> > + quality in a range. Valid range: from 0 to 51.
> > +
> > ``V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP (integer)``
> > Quantization parameter for an I frame for MPEG4. Valid range: from 1
> > to 31.
> > diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> > index 5e3806feb5d7..e2b0af0d2283 100644
> > --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> > +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> > @@ -825,6 +825,10 @@ const char *v4l2_ctrl_get_name(u32 id)
> > case V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER:return "H264 Number of HC Layers";
> > case V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER_QP:
> > return "H264 Set QP Value for HC Layers";
> > + case V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP: return "H264 I-Frame Minimum QP Value";
> > + case V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP: return "H264 I-Frame Maximum QP Value";
> > + case V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP: return "H264 P-Frame Minimum QP Value";
> > + case V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP: return "H264 P-Frame Maximum QP Value";
> > case V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP: return "MPEG4 I-Frame QP Value";
> > case V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP: return "MPEG4 P-Frame QP Value";
> > case V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP: return "MPEG4 B-Frame QP Value";
> > diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> > index 3dcfc6148f99..9519673e6437 100644
> > --- a/include/uapi/linux/v4l2-controls.h
> > +++ b/include/uapi/linux/v4l2-controls.h
> > @@ -533,6 +533,12 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type {
> > };
> > #define V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER (V4L2_CID_MPEG_BASE+381)
> > #define V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER_QP (V4L2_CID_MPEG_BASE+382)
> > +
> > +#define V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP (V4L2_CID_MPEG_BASE+390)
> > +#define V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP (V4L2_CID_MPEG_BASE+391)
> > +#define V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP (V4L2_CID_MPEG_BASE+392)
> > +#define V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP (V4L2_CID_MPEG_BASE+393)
> > +
> > #define V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP (V4L2_CID_MPEG_BASE+400)
> > #define V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP (V4L2_CID_MPEG_BASE+401)
> > #define V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP (V4L2_CID_MPEG_BASE+402)
> >
>


--
Fish Lin | Software Engineer | linfish@google.com | +886-921-925519

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