Re: Re: Re: [PATCH v10 11/17] media: uapi: Add... | linux-arm-kernel

quoted

Dne sreda, 06. julij 2022 ob 20:39:41 CEST je Ezequiel Garcia napisal(a):
Hi Jernej,

On Tue, Jul 5, 2022 at 1:11 PM Jernej Škrabec [off-list ref] 
wrote:
Dne torek, 05. julij 2022 ob 18:03:28 CEST je Benjamin Gaignard 
napisal(a):
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@collabora.com>
Acked-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Tested-by: Jernej Skrabec <jernej.skrabec@gmail.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
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.
Yeah, this field must be set even when entry points offset control isn't
used. Additionally, if entry point offsets control is needed and if
submitting multiple slices at once, length of entry point offsets array
must be sum of num_entry_point_offsets of all slices in that job. Not
sure where to put this explanation.
This confused me a bit: so you mean that this field (called
num_entry_point_offsets)
must be the sum of "num_entry_point_offsets" syntax elements for
slices in the request?
No, it's the other way around. num_entry_point_offsets field has same meaning as 
in syntax. It's per slice property. I said that if there is control with all 
entry point offsets, it has to have number of elements, which is sum of all 
num_entry_point_offsets fields in slice array.

Example (totaly made up):

Frame has 4 slices, each with 16 entry points.
App sends only 2 slices per job. Both num_entry_point_offsets fields in slice 
control will have value 16, but entry point offsets array control will have 32 
elements (16 entry points offsets from first and 16 entry point offsets from 
second slice).

Best regards,
Jernej

If this is the case, then perhaps it will be a mistake to name our V4L2
field exactly like the syntax element, since it this sum meaning.
Otherwise, developers would tend to get confused by it.

What do you think?

Thanks,
Ezequiel

Best regards,
Jernej

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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