Re: [PATCH v3 08/14] media: v4l: Add definitions for MPEG2 frame format and header metadata

[Hans Verkuil <hverkuil@xs4all.nl>]

On 07/05/18 14:44, Paul Kocialkowski wrote:
> From: Florent Revest <florent.revest@free-electrons.com>
> 
> Stateless video decoding engines require both the MPEG slices and
> associated metadata from the video stream in order to decode frames.
> 
> This introduces definitions for a new pixel format, describing buffers
> with MPEG2 slice data, as well as a control structure for passing the
> frame header (metadata) to drivers.
> 
> Signed-off-by: Florent Revest <florent.revest@free-electrons.com>
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> ---
>  drivers/media/v4l2-core/v4l2-ctrls.c | 10 ++++++++++
>  drivers/media/v4l2-core/v4l2-ioctl.c |  1 +
>  include/uapi/linux/v4l2-controls.h   | 26 ++++++++++++++++++++++++++
>  include/uapi/linux/videodev2.h       |  3 +++
>  4 files changed, 40 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index df58a23eb731..cdf860c8e3d8 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -826,6 +826,7 @@ const char *v4l2_ctrl_get_name(u32 id)
>  	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_KEY_FRAME:		return "Force Key Frame";
> +	case V4L2_CID_MPEG_VIDEO_MPEG2_FRAME_HDR:		return "MPEG2 Frame Header";

This compound control needs to be documented in the V4l2 spec.

>  
>  	/* VPX controls */
>  	case V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS:		return "VPX Number of Partitions";
> @@ -1271,6 +1272,9 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
>  	case V4L2_CID_RDS_TX_ALT_FREQS:
>  		*type = V4L2_CTRL_TYPE_U32;
>  		break;
> +	case V4L2_CID_MPEG_VIDEO_MPEG2_FRAME_HDR:
> +		*type = V4L2_CTRL_TYPE_MPEG2_FRAME_HDR;
> +		break;
>  	default:
>  		*type = V4L2_CTRL_TYPE_INTEGER;
>  		break;
> @@ -1591,6 +1595,9 @@ static int std_validate(const struct v4l2_ctrl *ctrl, u32 idx,
>  			return -ERANGE;
>  		return 0;
>  
> +	case V4L2_CTRL_TYPE_MPEG2_FRAME_HDR:
> +		return 0;
> +
>  	default:
>  		return -EINVAL;
>  	}
> @@ -2165,6 +2172,9 @@ static struct v4l2_ctrl *v4l2_ctrl_new(struct v4l2_ctrl_handler *hdl,
>  	case V4L2_CTRL_TYPE_U32:
>  		elem_size = sizeof(u32);
>  		break;
> +	case V4L2_CTRL_TYPE_MPEG2_FRAME_HDR:
> +		elem_size = sizeof(struct v4l2_ctrl_mpeg2_frame_hdr);
> +		break;
>  	default:
>  		if (type < V4L2_CTRL_COMPOUND_TYPES)
>  			elem_size = sizeof(s32);
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index 561a1fe3160b..38d318c47c55 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1274,6 +1274,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
>  		case V4L2_PIX_FMT_VP8:		descr = "VP8"; break;
>  		case V4L2_PIX_FMT_VP9:		descr = "VP9"; break;
>  		case V4L2_PIX_FMT_HEVC:		descr = "HEVC"; break; /* aka H.265 */
> +		case V4L2_PIX_FMT_MPEG2_FRAME:	descr = "MPEG2 Frame"; break;

Needs to be documented in the spec.

>  		case V4L2_PIX_FMT_CPIA1:	descr = "GSPCA CPiA YUV"; break;
>  		case V4L2_PIX_FMT_WNVA:		descr = "WNVA"; break;
>  		case V4L2_PIX_FMT_SN9C10X:	descr = "GSPCA SN9C10X"; break;
> diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> index 8d473c979b61..23da8bfa7e6f 100644
> --- a/include/uapi/linux/v4l2-controls.h
> +++ b/include/uapi/linux/v4l2-controls.h
> @@ -557,6 +557,8 @@ enum v4l2_mpeg_video_mpeg4_profile {
>  };
>  #define V4L2_CID_MPEG_VIDEO_MPEG4_QPEL		(V4L2_CID_MPEG_BASE+407)
>  
> +#define V4L2_CID_MPEG_VIDEO_MPEG2_FRAME_HDR     (V4L2_CID_MPEG_BASE+450)
> +
>  /*  Control IDs for VP8 streams
>   *  Although VP8 is not part of MPEG we add these controls to the MPEG class
>   *  as that class is already handling other video compression standards
> @@ -1076,4 +1078,28 @@ enum v4l2_detect_md_mode {
>  #define V4L2_CID_DETECT_MD_THRESHOLD_GRID	(V4L2_CID_DETECT_CLASS_BASE + 3)
>  #define V4L2_CID_DETECT_MD_REGION_GRID		(V4L2_CID_DETECT_CLASS_BASE + 4)
>  
> +struct v4l2_ctrl_mpeg2_frame_hdr {
> +	__u32 slice_len;
> +	__u32 slice_pos;
> +	enum { MPEG1, MPEG2 } type;

Still an enum?

> +
> +	__u16 width;
> +	__u16 height;
> +
> +	enum { PCT_I = 1, PCT_P, PCT_B, PCT_D } picture_coding_type;
> +	__u8 f_code[2][2];
> +
> +	__u8 intra_dc_precision;
> +	__u8 picture_structure;
> +	__u8 top_field_first;
> +	__u8 frame_pred_frame_dct;
> +	__u8 concealment_motion_vectors;
> +	__u8 q_scale_type;
> +	__u8 intra_vlc_format;
> +	__u8 alternate_scan;
> +
> +	__u8 backward_ref_index;
> +	__u8 forward_ref_index;
> +};
> +
>  #endif
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 1f6c4b52baae..d8f9b59d90d7 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -636,6 +636,7 @@ struct v4l2_pix_format {
>  #define V4L2_PIX_FMT_VP8      v4l2_fourcc('V', 'P', '8', '0') /* VP8 */
>  #define V4L2_PIX_FMT_VP9      v4l2_fourcc('V', 'P', '9', '0') /* VP9 */
>  #define V4L2_PIX_FMT_HEVC     v4l2_fourcc('H', 'E', 'V', 'C') /* HEVC aka H.265 */
> +#define V4L2_PIX_FMT_MPEG2_FRAME v4l2_fourcc('M', 'G', '2', 'F') /* MPEG2 frame */
>  
>  /*  Vendor-specific formats   */
>  #define V4L2_PIX_FMT_CPIA1    v4l2_fourcc('C', 'P', 'I', 'A') /* cpia1 YUV */
> @@ -1587,6 +1588,7 @@ struct v4l2_ext_control {
>  		__u8 __user *p_u8;
>  		__u16 __user *p_u16;
>  		__u32 __user *p_u32;
> +		struct v4l2_ctrl_mpeg2_frame_hdr __user *p_mpeg2_frame_hdr;
>  		void __user *ptr;
>  	};
>  } __attribute__ ((packed));
> @@ -1632,6 +1634,7 @@ enum v4l2_ctrl_type {
>  	V4L2_CTRL_TYPE_U8	     = 0x0100,
>  	V4L2_CTRL_TYPE_U16	     = 0x0101,
>  	V4L2_CTRL_TYPE_U32	     = 0x0102,
> +	V4L2_CTRL_TYPE_MPEG2_FRAME_HDR = 0x0109,
>  };
>  
>  /*  Used in the VIDIOC_QUERYCTRL ioctl for querying controls */
> 

Regards,

	Hans