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SubjectRe: [PATCH v5 04/17] media: uapi: HEVC: Add missing fields in HEVC controls
On 07.04.2022 17:29, Benjamin Gaignard wrote:
>Complete the HEVC controls with missing fields from H.265 specifications.
>Even if these fields aren't used by the current mainlined drivers
>they will be need for (at least) rkvdec driver.

s/be need/be required/
or
s/be need/be needed/

s/rkvdec/the rkvdec/

>
>Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
>---
> .../media/v4l/ext-ctrls-codec.rst | 19 +++++++++++++++++++
> include/media/hevc-ctrls.h | 6 +++++-
> 2 files changed, 24 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 4cd7c541fc30..dbb08603217b 100644
>--- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
>+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
>@@ -2661,6 +2661,16 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
> :stub-columns: 0
> :widths: 1 1 2
>
>+ * - __u8
>+ - ``video_parameter_set_id``
>+ - Specifies the value of the vps_video_parameter_set_id of the active VPS
>+ as descibed in section "7.4.3.2.1 General sequence parameter set RBSP semantics"
>+ of H.265 specifications.
>+ * - __u8
>+ - ``seq_parameter_set_id``
>+ - Provides an identifier for the SPS for reference by other syntax elements
>+ as descibed in section "7.4.3.2.1 General sequence parameter set RBSP semantics"
>+ of H.265 specifications.
> * - __u16
> - ``pic_width_in_luma_samples``
> -
>@@ -2800,6 +2810,9 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
> :stub-columns: 0
> :widths: 1 1 2
>
>+ * - __u8
>+ - ``pic_parameter_set_id``
>+ - Identifies the PPS for reference by other syntax elements.
> * - __u8
> - ``num_extra_slice_header_bits``
> -
>@@ -3026,6 +3039,12 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
> * - __u8
> - ``ref_idx_l1[V4L2_HEVC_DPB_ENTRIES_NUM_MAX]``
> - The list of L1 reference elements as indices in the DPB.
>+ * - __u16
>+ - ``short_term_ref_pic_set_size``
>+ - Specifies the size of short-term reference pictures set included in the SPS.

s/size of/size of the/

Section 7.4.8 depicts that the st_ref_pic_set syntax
structure can be part of the SPS or the slice header.

I think we should mention that we talk about the size of the st_ref_pic_set
syntax structure from section 7.4.8 of the specification.

>+ * - __u16
>+ - ``long_term_ref_pic_set_size``
>+ - Specifies the size of long-term reference pictures set include in the SPS.

s/size of/size of the/

Can we make this a bit more helpful? The specification doesn't contain
a similar structure to `st_ref_pic_set` for long term pictures. So, as a
programmer this leaves me guessing:
- Which syntax structure's size are we talking about?
- Does this correlate to any of the existing sections of the
specification?
Because in the end, I feel like this documentation should be able to
help a programmer to provide the correct data for the uABI.

Greetings,
Sebastian

> * - __u8
> - ``padding``
> - Applications and drivers must set this to zero.
>diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
>index 01ccda48d8c5..a329e086a89a 100644
>--- a/include/media/hevc-ctrls.h
>+++ b/include/media/hevc-ctrls.h
>@@ -58,6 +58,8 @@ enum v4l2_mpeg_video_hevc_start_code {
> /* The controls are not stable at the moment and will likely be reworked. */
> struct v4l2_ctrl_hevc_sps {
> /* ISO/IEC 23008-2, ITU-T Rec. H.265: Sequence parameter set */
>+ __u8 video_parameter_set_id;
>+ __u8 seq_parameter_set_id;
> __u16 pic_width_in_luma_samples;
> __u16 pic_height_in_luma_samples;
> __u8 bit_depth_luma_minus8;
>@@ -108,6 +110,7 @@ struct v4l2_ctrl_hevc_sps {
>
> struct v4l2_ctrl_hevc_pps {
> /* ISO/IEC 23008-2, ITU-T Rec. H.265: Picture parameter set */
>+ __u8 pic_parameter_set_id;
> __u8 num_extra_slice_header_bits;
> __u8 num_ref_idx_l0_default_active_minus1;
> __u8 num_ref_idx_l1_default_active_minus1;
>@@ -199,7 +202,8 @@ struct v4l2_ctrl_hevc_slice_params {
> __u32 slice_segment_addr;
> __u8 ref_idx_l0[V4L2_HEVC_DPB_ENTRIES_NUM_MAX];
> __u8 ref_idx_l1[V4L2_HEVC_DPB_ENTRIES_NUM_MAX];
>-
>+ __u16 short_term_ref_pic_set_size;
>+ __u16 long_term_ref_pic_set_size;
> __u8 padding;
>
> /* ISO/IEC 23008-2, ITU-T Rec. H.265: Weighted prediction parameter */
>--
>2.32.0
>

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