lkml.org 
[lkml]   [2022]   [May]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH v6 11/17] media: uapi: Add V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS control
    From
    On 29/05/2022 08:40, Jernej Škrabec wrote:
    > Hi!
    >
    > This series looks very good and I plan to test it shortly on Cedrus, but I
    > have one major concern below.
    >
    > Dne petek, 27. maj 2022 ob 16:31:28 CEST je Benjamin Gaignard napisal(a):
    >> The number of 'entry point offset' can be very variable.
    >> Instead of using a large static array define a v4l2 dynamic array
    >> of U32 (V4L2_CTRL_TYPE_U32).
    >> The number of entry point offsets is reported by the elems field
    >> and in struct v4l2_ctrl_hevc_slice_params.num_entry_point_offsets
    >> field.
    >
    > Slice control by itself is variable length array, so you would actually need
    > 2D variable array for entry points which is not supported. However, easy
    > workaround for that is to flatten 2D array to 1D and either have another slice
    > control field which would tell first entry point index for convenience or let
    > driver calculate it by adding up all num_entry_point_offsets of previous
    > slices.
    >
    > Hans, what do you think?

    If I would support 2D variable array sizes, wouldn't that be more elegant?

    The current implementation doesn't support that, but as the commit log for
    patch 1/17 says:

    "Currently dynamically sized arrays are limited to one dimensional arrays,
    but that might change in the future if there is a need for it."

    Let me know if you agree, and I'll try to implement this. It's been a while
    since I last looked at this, so I'm not sure how much work it is, but it is
    probably worth a shot.

    Regards,

    Hans

    >
    > Note, it seems that H265 decoding on Cedrus still works without entry points,
    > so this problem can be solved later. I'm not sure what we lose with that but
    > it was suggested that this could influence speed or error resilience or both.
    > However, I think we're close to solve it, so I'd like to do that now.
    >
    > Best regards,
    > Jernej
    >
    >>
    >> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
    >> ---
    >> .../userspace-api/media/v4l/ext-ctrls-codec.rst | 11 +++++++++++
    >> drivers/media/v4l2-core/v4l2-ctrls-defs.c | 5 +++++
    >> include/media/hevc-ctrls.h | 5 ++++-
    >> 3 files changed, 20 insertions(+), 1 deletion(-)
    >>
    >> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/
    > Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
    >> index 0796b1563daa..05228e280f66 100644
    >> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
    >> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
    >> @@ -3010,6 +3010,9 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
    >> * - __u32
    >> - ``data_bit_offset``
    >> - Offset (in bits) to the video data in the current slice data.
    >> + * - __u32
    >> + - ``num_entry_point_offsets``
    >> + - Specifies the number of entry point offset syntax elements in the
    > slice header.
    >> * - __u8
    >> - ``nal_unit_type``
    >> - Specifies the coding type of the slice (B, P or I).
    >> @@ -3150,6 +3153,14 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
    >>
    >> \normalsize
    >>
    >> +``V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS (integer)``
    >> + Specifies entry point offsets in bytes.
    >> + This control is a dynamically sized array. The number of entry point
    >> + offsets is reported by the ``elems`` field.
    >> + This bitstream parameter is defined according to :ref:`hevc`.
    >> + They are described in section 7.4.7.1 "General slice segment header
    >> + semantics" of the specification.
    >> +
    >> ``V4L2_CID_STATELESS_HEVC_SCALING_MATRIX (struct)``
    >> Specifies the HEVC scaling matrix parameters used for the scaling
    > process
    >> for transform coefficients.
    >> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-
    > core/v4l2-ctrls-defs.c
    >> index d594efbcbb93..e22921e7ea61 100644
    >> --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
    >> +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
    >> @@ -1188,6 +1188,7 @@ const char *v4l2_ctrl_get_name(u32 id)
    >> case V4L2_CID_STATELESS_HEVC_DECODE_PARAMS: return
    > "HEVC Decode Parameters";
    >> case V4L2_CID_STATELESS_HEVC_DECODE_MODE: return
    > "HEVC Decode Mode";
    >> case V4L2_CID_STATELESS_HEVC_START_CODE: return
    > "HEVC Start Code";
    >> + case V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS: return
    > "HEVC Entry Point Offsets";
    >>
    >> /* Colorimetry controls */
    >> /* Keep the order of the 'case's the same as in v4l2-controls.h!
    > */
    >> @@ -1518,6 +1519,10 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum
    > v4l2_ctrl_type *type,
    >> case V4L2_CID_STATELESS_HEVC_DECODE_PARAMS:
    >> *type = V4L2_CTRL_TYPE_HEVC_DECODE_PARAMS;
    >> break;
    >> + case V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS:
    >> + *type = V4L2_CTRL_TYPE_U32;
    >> + *flags |= V4L2_CTRL_FLAG_DYNAMIC_ARRAY;
    >> + break;
    >> case V4L2_CID_STATELESS_VP9_COMPRESSED_HDR:
    >> *type = V4L2_CTRL_TYPE_VP9_COMPRESSED_HDR;
    >> break;
    >> diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
    >> index a3c829ef531a..1319cb99ae3f 100644
    >> --- a/include/media/hevc-ctrls.h
    >> +++ b/include/media/hevc-ctrls.h
    >> @@ -20,6 +20,7 @@
    >> #define V4L2_CID_STATELESS_HEVC_DECODE_PARAMS (V4L2_CID_CODEC_BASE
    > + 1012)
    >> #define V4L2_CID_STATELESS_HEVC_DECODE_MODE (V4L2_CID_CODEC_BASE + 1015)
    >> #define V4L2_CID_STATELESS_HEVC_START_CODE (V4L2_CID_CODEC_BASE + 1016)
    >> +#define V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS (V4L2_CID_CODEC_BASE +
    > 1017)
    >>
    >> /* enum v4l2_ctrl_type type values */
    >> #define V4L2_CTRL_TYPE_HEVC_SPS 0x0120
    >> @@ -318,6 +319,8 @@ struct v4l2_hevc_pred_weight_table {
    >> *
    >> * @bit_size: size (in bits) of the current slice data
    >> * @data_bit_offset: offset (in bits) to the video data in the current slice
    > data
    >> + * @num_entry_point_offsets: specifies the number of entry point offset syntax
    >> + * elements in the slice header.
    >> * @nal_unit_type: specifies the coding type of the slice (B, P or I)
    >> * @nuh_temporal_id_plus1: minus 1 specifies a temporal identifier for the
    > NAL unit
    >> * @slice_type: see V4L2_HEVC_SLICE_TYPE_{}
    >> @@ -360,7 +363,7 @@ struct v4l2_hevc_pred_weight_table {
    >> struct v4l2_ctrl_hevc_slice_params {
    >> __u32 bit_size;
    >> __u32 data_bit_offset;
    >> -
    >> + __u32 num_entry_point_offsets;
    >> /* ISO/IEC 23008-2, ITU-T Rec. H.265: NAL unit header */
    >> __u8 nal_unit_type;
    >> __u8 nuh_temporal_id_plus1;
    >> --
    >> 2.32.0
    >>
    >>
    >
    >

    \
     
     \ /
      Last update: 2022-05-30 11:20    [W:3.145 / U:0.396 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site