Re: [PATCH v2 1/2] v4l: add V4L2_CID_MPEG_VIDEO_FORCE_I_FRAME.

[Hans Verkuil <hverkuil@xs4all.nl>]

On 01/14/16 09:33, Wu-Cheng Li wrote:
> Some drivers also need a control like
> V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE to force an encoder
> I frame. Add a general V4L2_CID_MPEG_VIDEO_FORCE_I_FRAME
> so the new drivers and applications can use it.
> 
> Signed-off-by: Wu-Cheng Li <wuchengli@chromium.org>
> ---
>  Documentation/DocBook/media/v4l/controls.xml | 8 ++++++++
>  drivers/media/v4l2-core/v4l2-ctrls.c         | 2 ++
>  include/uapi/linux/v4l2-controls.h           | 1 +
>  3 files changed, 11 insertions(+)
> 
> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
> index f13a429..6760cf5 100644
> --- a/Documentation/DocBook/media/v4l/controls.xml
> +++ b/Documentation/DocBook/media/v4l/controls.xml
> @@ -2330,6 +2330,14 @@ vertical search range for motion estimation module in video encoder.</entry>
>  	      </row>
>  
>  	      <row><entry></entry></row>
> +	      <row id="v4l2-mpeg-video-force-i-frame">
> +		<entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_FORCE_I_FRAME</constant>&nbsp;</entry>
> +		<entry>button</entry>
> +	      </row><row><entry spanname="descr">Force an I frame for the next queued buffer. Applicable to encoders.
> +This is a general, codec-agnostic keyframe control.</entry>
> +	      </row>
> +
> +	      <row><entry></entry></row>
>  	      <row>
>  		<entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_H264_CPB_SIZE</constant>&nbsp;</entry>
>  		<entry>integer</entry>
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index c9d5537..33ecb7b 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -747,6 +747,7 @@ const char *v4l2_ctrl_get_name(u32 id)
>  	case V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE:		return "Horizontal MV Search Range";
>  	case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE:		return "Vertical MV Search Range";
>  	case V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER:		return "Repeat Sequence Header";
> +	case V4L2_CID_MPEG_VIDEO_FORCE_I_FRAME:			return "Force an I frame";

I would suggest renaming this to Key Frame. This is consistent with the V4L2_BUF_FLAG_KEYFRAME
flag and, I think, also more generic than 'I Frame'.

So the define would become V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME and the control
description "Force Key Frame". The docbook text needs to be updated as well.

With those changes this looks good to me.

Regards,

	Hans

>  
>  	/* VPX controls */
>  	case V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS:		return "VPX Number of Partitions";
> @@ -985,6 +986,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
>  	case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE:
>  		*type = V4L2_CTRL_TYPE_INTEGER;
>  		break;
> +	case V4L2_CID_MPEG_VIDEO_FORCE_I_FRAME:
>  	case V4L2_CID_PAN_RESET:
>  	case V4L2_CID_TILT_RESET:
>  	case V4L2_CID_FLASH_STROBE:
> diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> index 2d225bc..1c911b8 100644
> --- a/include/uapi/linux/v4l2-controls.h
> +++ b/include/uapi/linux/v4l2-controls.h
> @@ -390,6 +390,7 @@ enum v4l2_mpeg_video_multi_slice_mode {
>  #define V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER		(V4L2_CID_MPEG_BASE+226)
>  #define V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE		(V4L2_CID_MPEG_BASE+227)
>  #define V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE		(V4L2_CID_MPEG_BASE+228)
> +#define V4L2_CID_MPEG_VIDEO_FORCE_I_FRAME		(V4L2_CID_MPEG_BASE+229)
>  
>  #define V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP		(V4L2_CID_MPEG_BASE+300)
>  #define V4L2_CID_MPEG_VIDEO_H263_P_FRAME_QP		(V4L2_CID_MPEG_BASE+301)
>