On Mon, 2018-01-29 at 14:27 +0100, Hans Verkuil wrote:

On 01/29/2018 01:42 PM, Smitha T Murthy wrote:

quoted

On Wed, 2018-01-24 at 15:16 +0100, Hans Verkuil wrote:

quoted

On 24/01/18 11:59, Smitha T Murthy wrote:

quoted

Added V4l2 controls for HEVC encoder

Signed-off-by: Smitha T Murthy <redacted>
---
 Documentation/media/uapi/v4l/extended-controls.rst | 400 +++++++++++++++++++++
 1 file changed, 400 insertions(+)

diff --git a/Documentation/media/uapi/v4l/extended-controls.rst b/Documentation/media/uapi/v4l/extended-controls.rst
index dfe49ae..46ee2bf 100644
--- a/Documentation/media/uapi/v4l/extended-controls.rst
+++ b/Documentation/media/uapi/v4l/extended-controls.rst

@@ -1960,6 +1960,406 @@ enum v4l2_vp8_golden_frame_sel -
     1, 2 and 3 corresponding to encoder profiles 0, 1, 2 and 3.
 
 
+High Efficiency Video Coding (HEVC/H.265) Control Reference
+-----------------------------------------------------------
+
+The HEVC/H.265 controls include controls for encoding parameters of HEVC/H.265
+video codec.
+
+
+.. _hevc-control-id:
+
+HEVC/H.265 Control IDs
+^^^^^^^^^^^^^^^^^^^^^^
+
+``V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP (integer)``
+    Minimum quantization parameter for HEVC.
+    Valid range: from 0 to 51.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP (integer)``
+    Maximum quantization parameter for HEVC.
+    Valid range: from 0 to 51.

You probably should mention the default values for MIN_QP and MAX_QP
(I assume those are 0 and 51 and are not driver specific).

Yes these values are not driver specific.
I followed the way MAX_QP and MIN_QP are defined for other codecs like
H264, H263, MPEG4 where only valid range is mentioned.

quoted

quoted

+
+``V4L2_CID_MPEG_VIDEO_HEVC_I_FRAME_QP (integer)``
+    Quantization parameter for an I frame for HEVC.
+    Valid range: from 0 to 51.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_P_FRAME_QP (integer)``
+    Quantization parameter for a P frame for HEVC.
+    Valid range: from 0 to 51.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_B_FRAME_QP (integer)``
+    Quantization parameter for a B frame for HEVC.
+    Valid range: from 0 to 51.

Sorry, this still isn't clear to me.

If I set V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP to 50, can I then still set
V4L2_CID_MPEG_VIDEO_HEVC_B_FRAME_QP to 51? Or is 50 then the maximum?

In other words, what is the relationship between these three controls
and the MIN_QP/MAX_QP controls.

If we set V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP as 50 then
V4L2_CID_MPEG_VIDEO_HEVC_B_FRAME_QP or
4L2_CID_MPEG_VIDEO_HEVC_I_FRAME_QP or
V4L2_CID_MPEG_VIDEO_HEVC_P_FRAME_QP will have maximum as 50.
Similarly for minimum as well, the above three controls will adhere to
the V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP set.
These controls have similar in relation as seen with
V4L2_CID_MPEG_VIDEO_H264_P_FRAME_QP and V4L2_CID_MPEG_VIDEO_H264_MAX_QP 

quoted

quoted

+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_QP (boolean)``
+    HIERARCHICAL_QP allows the host to specify the quantization parameter
+    values for each temporal layer through HIERARCHICAL_QP_LAYER. This is
+    valid only if HIERARCHICAL_CODING_LAYER is greater than 1. Setting the
+    control value to 1 enables setting of the QP values for the layers.
+
+.. _v4l2-hevc-hier-coding-type:
+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_TYPE``
+    (enum)
+
+enum v4l2_mpeg_video_hevc_hier_coding_type -
+    Selects the hierarchical coding type for encoding. Possible values are:
+
+.. raw:: latex
+
+    \begin{adjustbox}{width=\columnwidth}
+
+.. tabularcolumns:: |p{11.0cm}|p{10.0cm}|
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+
+    * - ``V4L2_MPEG_VIDEO_HEVC_HIERARCHICAL_CODING_B``
+      - Use the B frame for hierarchical coding.
+    * - ``V4L2_MPEG_VIDEO_HEVC_HIERARCHICAL_CODING_P``
+      - Use the P frame for hierarchical coding.
+
+.. raw:: latex
+
+    \end{adjustbox}
+
+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_LAYER (integer)``
+    Selects the hierarchical coding layer. In normal encoding
+    (non-hierarchial coding), it should be zero. Possible values are [0, 6].
+    0 indicates HIERARCHICAL CODING LAYER 0, 1 indicates HIERARCHICAL CODING
+    LAYER 1 and so on.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L0_QP (integer)``
+    Indicates quantization parameter for hierarchical coding layer 0.
+    For HEVC it can have a value of 0-51.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L1_QP (integer)``
+    Indicates quantization parameter for hierarchical coding layer 1.
+    For HEVC it can have a value of 0-51.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L2_QP (integer)``
+    Indicates quantization parameter for hierarchical coding layer 2.
+    For HEVC it can have a value of 0-51.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L3_QP (integer)``
+    Indicates quantization parameter for hierarchical coding layer 3.
+    For HEVC it can have a value of 0-51.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L4_QP (integer)``
+    Indicates quantization parameter for hierarchical coding layer 4.
+    For HEVC it can have a value of 0-51.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L5_QP (integer)``
+    Indicates quantization parameter for hierarchical coding layer 5.
+    For HEVC it can have a value of 0-51.
+
+``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L6_QP (integer)``
+    Indicates quantization parameter for hierarchical coding layer 6.
+    For HEVC it can have a value of 0-51.

Same here: how does MIN_QP/MAX_QP influence these controls, if at all.

Regards,

	Hans

The values set in V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP and
V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP will give the limits for the L0-L6 QP
values that can be set.

OK. If you can clarify this in the documentation, then I can Ack this.

Note: if userspace changes MIN_QP or MAX_QP, then the driver should call
v4l2_ctrl_modify_range() to update the ranges of the controls that are
impacted by QP range changes. I'm not sure if that's done at the moment.

Regards,

	Hans