Re: [PATCH v2] [media] v4l: add I / P frame min max QP definitions

From: Hans Verkuil <hverkuil-cisco@xs4all.nl>
To: Fish Lin <linfish@google.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Keiichi Watanabe <keiichiw@chromium.org>
Cc: Paul Kocialkowski <paul.kocialkowski@bootlin.com>,
	Will Deacon <will.deacon@arm.com>,
	Smitha T Murthy <smitha.t@samsung.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Tomasz Figa <tfiga@chromium.org>,
	linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
	trivial@kernel.org
Subject: Re: [PATCH v2] [media] v4l: add I / P frame min max QP definitions
Date: Wed, 30 Jan 2019 08:56:59 +0100	[thread overview]
Message-ID: <6de7d597-f89a-e20d-a1fd-3f683f4916b8@xs4all.nl> (raw)
In-Reply-To: <20190130074522.155770-1-linfish@google.com>

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)
> 