On 06/05/2024 10:49, Ming Qian wrote:
> Add a control V4L2_CID_MPEG_VIDEO_AVERAGE_QP to report the average qp
> value of current encoded frame. the value applies to the last dequeued
> capture buffer.
>
> Signed-off-by: Ming Qian <ming.qian@xxxxxxx>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Regards,
Hans
> ---
> v3
> - document the valid range of the new ctrl
>
> v2
> - improve document description according Hans's comments
> - drop volatile flag
>
> .../userspace-api/media/v4l/ext-ctrls-codec.rst | 14 ++++++++++++++
> drivers/media/v4l2-core/v4l2-ctrls-defs.c | 5 +++++
> include/uapi/linux/v4l2-controls.h | 2 ++
> 3 files changed, 21 insertions(+)
>
> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> index 2a165ae063fb..4a379bd9e3fb 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> @@ -1653,6 +1653,20 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
> Quantization parameter for a P frame for FWHT. Valid range: from 1
> to 31.
>
> +``V4L2_CID_MPEG_VIDEO_AVERAGE_QP (integer)``
> + This read-only control returns the average QP value of the currently
> + encoded frame. The value applies to the last dequeued capture buffer
> + (VIDIOC_DQBUF). Its valid range depends on the encoding format and parameters.
> + For H264, its valid range is from 0 to 51.
> + For HEVC, its valid range is from 0 to 51 for 8 bit and
> + from 0 to 63 for 10 bit.
> + For H263 and MPEG4, its valid range is from 1 to 31.
> + For VP8, its valid range is from 0 to 127.
> + For VP9, its valid range is from 0 to 255.
> + If the codec's MIN_QP and MAX_QP are set, then the QP will meet both requirements.
> + Codecs need to always use the specified range, rather then a HW custom range.
> + Applicable to encoders
> +
> .. raw:: latex
>
> \normalsize
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> index 8696eb1cdd61..1ea52011247a 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> @@ -970,6 +970,7 @@ const char *v4l2_ctrl_get_name(u32 id)
> case V4L2_CID_MPEG_VIDEO_LTR_COUNT: return "LTR Count";
> case V4L2_CID_MPEG_VIDEO_FRAME_LTR_INDEX: return "Frame LTR Index";
> case V4L2_CID_MPEG_VIDEO_USE_LTR_FRAMES: return "Use LTR Frames";
> + case V4L2_CID_MPEG_VIDEO_AVERAGE_QP: return "Average QP Value";
> case V4L2_CID_FWHT_I_FRAME_QP: return "FWHT I-Frame QP Value";
> case V4L2_CID_FWHT_P_FRAME_QP: return "FWHT P-Frame QP Value";
>
> @@ -1507,6 +1508,10 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
> *max = 0xffffffffffffLL;
> *step = 1;
> break;
> + case V4L2_CID_MPEG_VIDEO_AVERAGE_QP:
> + *type = V4L2_CTRL_TYPE_INTEGER;
> + *flags |= V4L2_CTRL_FLAG_READ_ONLY;
> + break;
> case V4L2_CID_PIXEL_RATE:
> *type = V4L2_CTRL_TYPE_INTEGER64;
> *flags |= V4L2_CTRL_FLAG_READ_ONLY;
> diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> index 99c3f5e99da7..974fd254e573 100644
> --- a/include/uapi/linux/v4l2-controls.h
> +++ b/include/uapi/linux/v4l2-controls.h
> @@ -898,6 +898,8 @@ enum v4l2_mpeg_video_av1_level {
> V4L2_MPEG_VIDEO_AV1_LEVEL_7_3 = 23
> };
>
> +#define V4L2_CID_MPEG_VIDEO_AVERAGE_QP (V4L2_CID_CODEC_BASE + 657)
> +
> /* MPEG-class control IDs specific to the CX2341x driver as defined by V4L2 */
> #define V4L2_CID_CODEC_CX2341X_BASE (V4L2_CTRL_CLASS_CODEC | 0x1000)
> #define V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE (V4L2_CID_CODEC_CX2341X_BASE+0)
