Re: [PATCH 1/3] media: uapi: h264: update reference lists

[Nicolas Dufresne <nicolas@ndufresne.ca>]

Le jeudi 04 juin 2020 à 20:57 +0200, Jernej Skrabec a écrit :
> When dealing with with interlaced frames, reference lists must tell if
> each particular reference is meant for top or bottom field. This info
> is currently not provided at all in the H264 related controls.
> 
> Make reference lists hold a structure which will also hold flags along
> index into DPB array. Flags will tell if reference is meant for top or
> bottom field.
> 
> Currently the only user of these lists is Cedrus which is just compile
> fixed here. Actual usage of newly introduced flags will come in
> following commit.
> 
> Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>

This looks like the right approach to me and is extensible if anything
else is needed for MVC and SVC special referencing (at least will be
enough for what H.264 actually supports in this regard).

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>

> ---
>  .../media/v4l/ext-ctrls-codec.rst             | 40 ++++++++++++++++++-
>  .../staging/media/sunxi/cedrus/cedrus_h264.c  |  6 +--
>  include/media/h264-ctrls.h                    | 12 +++++-
>  3 files changed, 51 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> index d0d506a444b1..6c36d298db20 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> @@ -1843,10 +1843,10 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
>      * - __u32
>        - ``slice_group_change_cycle``
>        -
> -    * - __u8
> +    * - struct :c:type:`v4l2_h264_reference`
>        - ``ref_pic_list0[32]``
>        - Reference picture list after applying the per-slice modifications
> -    * - __u8
> +    * - struct :c:type:`v4l2_h264_reference`
>        - ``ref_pic_list1[32]``
>        - Reference picture list after applying the per-slice modifications
>      * - __u32
> @@ -1926,6 +1926,42 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
>        - ``chroma_offset[32][2]``
>        -
>  
> +``Picture Reference``
> +
> +.. c:type:: v4l2_h264_reference
> +
> +.. cssclass:: longtable
> +
> +.. flat-table:: struct v4l2_h264_reference
> +    :header-rows:  0
> +    :stub-columns: 0
> +    :widths:       1 1 2
> +
> +    * - __u16
> +      - ``flags``
> +      - See :ref:`Picture Reference Flags <h264_reference_flags>`
> +    * - __u8
> +      - ``index``
> +      -
> +
> +.. _h264_reference_flags:
> +
> +``Picture Reference Flags``
> +
> +.. cssclass:: longtable
> +
> +.. flat-table::
> +    :header-rows:  0
> +    :stub-columns: 0
> +    :widths:       1 1 2
> +
> +    * - ``V4L2_H264_REFERENCE_FLAG_TOP_FIELD``
> +      - 0x00000001
> +      -
> +    * - ``V4L2_H264_REFERENCE_FLAG_BOTTOM_FIELD``
> +      - 0x00000002
> +      -
> +
>  ``V4L2_CID_MPEG_VIDEO_H264_DECODE_PARAMS (struct)``
>      Specifies the decode parameters (as extracted from the bitstream)
>      for the associated H264 slice data. This includes the necessary
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> index 54ee2aa423e2..cce527bbdf86 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> @@ -166,8 +166,8 @@ static void cedrus_write_frame_list(struct cedrus_ctx *ctx,
>  
>  static void _cedrus_write_ref_list(struct cedrus_ctx *ctx,
>  				   struct cedrus_run *run,
> -				   const u8 *ref_list, u8 num_ref,
> -				   enum cedrus_h264_sram_off sram)
> +				   const struct v4l2_h264_reference *ref_list,
> +				   u8 num_ref, enum cedrus_h264_sram_off sram)
>  {
>  	const struct v4l2_ctrl_h264_decode_params *decode = run->h264.decode_params;
>  	struct vb2_queue *cap_q;
> @@ -188,7 +188,7 @@ static void _cedrus_write_ref_list(struct cedrus_ctx *ctx,
>  		int buf_idx;
>  		u8 dpb_idx;
>  
> -		dpb_idx = ref_list[i];
> +		dpb_idx = ref_list[i].index;
>  		dpb = &decode->dpb[dpb_idx];
>  
>  		if (!(dpb->flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
> diff --git a/include/media/h264-ctrls.h b/include/media/h264-ctrls.h
> index 080fd1293c42..9b1cbc9bc38e 100644
> --- a/include/media/h264-ctrls.h
> +++ b/include/media/h264-ctrls.h
> @@ -140,6 +140,14 @@ struct v4l2_h264_pred_weight_table {
>  #define V4L2_H264_SLICE_FLAG_DIRECT_SPATIAL_MV_PRED	0x04
>  #define V4L2_H264_SLICE_FLAG_SP_FOR_SWITCH		0x08
>  
> +#define V4L2_H264_REFERENCE_FLAG_TOP_FIELD		0x01
> +#define V4L2_H264_REFERENCE_FLAG_BOTTOM_FIELD		0x02
> +
> +struct v4l2_h264_reference {
> +	__u8 flags;
> +	__u8 index;
> +};
> +
>  struct v4l2_ctrl_h264_slice_params {
>  	/* Size in bytes, including header */
>  	__u32 size;
> @@ -182,8 +190,8 @@ struct v4l2_ctrl_h264_slice_params {
>  	 * Entries on each list are indices into
>  	 * v4l2_ctrl_h264_decode_params.dpb[].
>  	 */
> -	__u8 ref_pic_list0[32];
> -	__u8 ref_pic_list1[32];
> +	struct v4l2_h264_reference ref_pic_list0[32];
> +	struct v4l2_h264_reference ref_pic_list1[32];
>  
>  	__u32 flags;
>  };