Re: [PATCH v10 11/17] media: uapi: Add V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS control

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Le 05/07/2022 à 17:45, Ezequiel Garcia a écrit :
Hi guys,

On Tue, Jul 05, 2022 at 10:54:14AM +0200, Benjamin Gaignard wrote:
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.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
Acked-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
Tested-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
---
  .../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 db0df7d9f27c..8df8d7fdfe70 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.
This looks underdocumented. Somewhere in the docs it should be mentioned
that the field 'num_entry_point_offsets' is linked to the control
V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS.

This field is here because some drivers would like know the number of
entry point offsets without getting the entry point offsets data itself.

Benjamin


Thanks,
Ezequiel

      * - __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 a372c184689e..3a6601a46ced 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
@@ -316,6 +317,8 @@ 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_{}
@@ -358,7 +361,7 @@ 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





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