media: uapi: HEVC: Add num_delta_pocs_of_ref_rps_idx field

Some drivers firmwares parse by themselves slice header and need
num_delta_pocs_of_ref_rps_idx value to parse slice header
short_term_ref_pic_set().
Use one of the 4 reserved bytes to store this value without
changing the v4l2_ctrl_hevc_decode_params structure size and padding.

This value also exist in DXVA API.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil: fix typo in num_delta_pocs_of_ref_rps_idx doc]

1 files changed, 7 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
index 3d8411acd5b8..677bf0fbcc5a 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
@@ -2923,6 +2923,13 @@ This structure contains all loop filter related parameters. See sections
       - ``poc_lt_curr[V4L2_HEVC_DPB_ENTRIES_NUM_MAX]``
       - PocLtCurr as described in section 8.3.2 "Decoding process for reference
         picture set": provides the index of the long term references in DPB array.
+    * - __u8
+      - ``num_delta_pocs_of_ref_rps_idx``
+      - When the short_term_ref_pic_set_sps_flag in the slice header is equal to 0,
+        it is the same as the derived value NumDeltaPocs[RefRpsIdx]. It can be used to parse
+        the RPS data in slice headers instead of skipping it with @short_term_ref_pic_set_size.
+        When the value of short_term_ref_pic_set_sps_flag in the slice header is
+        equal to 1, num_delta_pocs_of_ref_rps_idx shall be set to 0.
     * - struct :c:type:`v4l2_hevc_dpb_entry`
       - ``dpb[V4L2_HEVC_DPB_ENTRIES_NUM_MAX]``
       - The decoded picture buffer, for meta-data about reference frames.