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

From: Hans Verkuil
Date: Mon May 07 2018 - 09:49:57 EST

On 07/05/18 14:44, Paul Kocialkowski wrote:
> From: Florent Revest <florent.revest@xxxxxxxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
> ---
> 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