Re: [Patch v5 12/12] Documention: v4l: Documentation for HEVC CIDs

Hans Verkuil
2017-07-20T14:50:41Z

On 19/06/17 07:10, Smitha T Murthy wrote:
> Added V4l2 controls for HEVC encoder
>
> Signed-off-by: Smitha T Murthy <smitha.t@samsung.com>
> ---
> Documentation/media/uapi/v4l/extended-controls.rst | 364 +++++++++++++++++++++
> 1 file changed, 364 insertions(+)
>
> diff --git a/Documentation/media/uapi/v4l/extended-controls.rst b/Documentation/media/uapi/v4l/extended-controls.rst
> index abb1057..7767c70 100644
> --- a/Documentation/media/uapi/v4l/extended-controls.rst
> +++ b/Documentation/media/uapi/v4l/extended-controls.rst
> @@ -1960,6 +1960,370 @@ 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.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP (integer)``
> + Maximum quantization parameter for HEVC.

It's a bit ambiguous. Are these supposed to be read-only parameters?
Normally min-max is already implied in the control range, so this is a
bit odd. Perhaps it is clear for people who know HEVC, but I'm not
quite sure what to make of it.

> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_I_FRAME_QP (integer)``
> + Quantization parameter for an I frame for HEVC.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_P_FRAME_QP (integer)``
> + Quantization parameter for a P frame for HEVC.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_B_FRAME_QP (integer)``
> + Quantization parameter for a B frame for HEVC.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_HIER_QP (boolean)``
> + HIERARCHICAL_QP allows 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_LAYER_QP (integer)``
> + Indicates the hierarchical coding layer quantization parameter.
> + For HEVC it can have a value of 0-51. Hence in the control value passed
> + the LSB 16 bits will indicate the quantization parameter. The MSB 16 bit
> + will pass the layer(0-6) it is meant for.

This is ugly. Why not make this an array control? This really is an array of
7 values, right? An alternative is to split this in 7 controls just as you did
with V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L?_BR.

The way it is now doesn't work either since G_CTRL(V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_LAYER_QP)
would just return the QP for whatever was the last layer you set it for and you can't
query it for another layer.

> +
> +.. _v4l2-hevc-profile:
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_PROFILE``
> + (enum)
> +
> +enum v4l2_mpeg_video_hevc_profile -
> + Select the desired profile for HEVC encoder.
> +
> +.. 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_PROFILE_MAIN``
> + - Main profile.
> + * - ``V4L2_MPEG_VIDEO_HEVC_PROFILE_MAIN_STILL_PICTURE``
> + - Main still picture profile.
> +
> +.. raw:: latex
> +
> + \end{adjustbox}
> +
> +
> +.. _v4l2-hevc-level:
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_LEVEL``
> + (enum)
> +
> +enum v4l2_mpeg_video_hevc_level -
> + Selects the desired level for HEVC encoder.
> +
> +.. 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_LEVEL_1``
> + - Level 1.0
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_2``
> + - Level 2.0
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_2_1``
> + - Level 2.1
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_3``
> + - Level 3.0
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_3_1``
> + - Level 3.1
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_4``
> + - Level 4.0
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_4_1``
> + - Level 4.1
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_5``
> + - Level 5.0
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_5_1``
> + - Level 5.1
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_5_2``
> + - Level 5.2
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_6``
> + - Level 6.0
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_6_1``
> + - Level 6.1
> + * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_6_2``
> + - Level 6.2
> +
> +.. raw:: latex
> +
> + \end{adjustbox}
> +
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_FRAME_RATE_RESOLUTION (integer)``
> + Indicates the number of evenly spaced subintervals, called ticks, within
> + one second. This is a 16bit unsigned integer and has a maximum value up to

16bit -> 16 bit

> + 0xffff.

Is there a HEVC-defined minimum value as well? You mention the max value, but not
the min value, so it made me wonder...

> +
> +.. _v4l2-hevc-tier-flag:
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_TIER_FLAG``
> + (enum)
> +
> +enum v4l2_mpeg_video_hevc_tier_flag -
> + TIER_FLAG specifies tiers information of the HEVC encoded picture. Tier
> + were made to deal with applications that differ in terms of maximum bit
> + rate. Setting the flag to 0 selects HEVC tier_flag as Main tier and setting
> + this flag to 1 indicates High tier. High tier is for applications requiring
> + high bit rates.
> +
> +.. 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_TIER_MAIN``
> + - Main tier.
> + * - ``V4L2_MPEG_VIDEO_HEVC_TIER_HIGH``
> + - High tier.
> +
> +.. raw:: latex
> +
> + \end{adjustbox}
> +
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_MAX_PARTITION_DEPTH (integer)``
> + Selects HEVC maximum coding unit depth.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_LF (boolean)``
> + Indicates loop filtering. Control value 1 indicates loop filtering
> + is enabled and when set to 0 indicates loop filtering is disabled.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_LF_SLICE_BOUNDARY (boolean)``
> + Selects whether to apply the loop filter across the slice boundary or not.
> + If the value is 0, loop filter will not be applied across the slice boundary.
> + If the value is 1, loop filter will be applied across the slice boundary.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_LF_BETA_OFFSET_DIV2 (integer)``
> + Selects HEVC loop filter beta offset. The valid range is [-6, +6].
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_LF_TC_OFFSET_DIV2 (integer)``
> + Selects HEVC loop filter tc offset. The valid range is [-6, +6].
> +
> +.. _v4l2-hevc-refresh-type:
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_REFRESH_TYPE``
> + (enum)
> +
> +enum v4l2_mpeg_video_hevc_hier_refresh_type -
> + Selects refresh type for HEVC encoder.
> + Host has to specify the period into
> + HEVC_REFRESH_PERIOD.

'into HEVC_REFRESH_PERIOD' -> with the ``V4L2_CID_MPEG_VIDEO_HEVC_REFRESH_PERIOD`` control

> +
> +.. 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_REFRESH_NONE``
> + - Use the B frame for hierarchical coding.
> + * - ``V4L2_MPEG_VIDEO_HEVC_REFRESH_CRA``
> + - Use CRA (Clean Random Access Unit) picture encoding.
> + * - ``V4L2_MPEG_VIDEO_HEVC_REFRESH_IDR``
> + - Use IDR picture encoding.
> +
> +.. raw:: latex
> +
> + \end{adjustbox}
> +
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_REFRESH_PERIOD (integer)``
> + Selects the refresh period for HEVC encoder.
> + This specifies the number of I pictures between two CRA/IDR pictures.
> + This is valid only if REFRESH_TYPE is not 0.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_LOSSLESS_CU (boolean)``
> + Indicates HEVC lossless encoding. Setting it to 0 disables lossless
> + encoding. Setting it to 1 enables lossless encoding.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_CONST_INTRA_PRED (boolean)``
> + Indicates constant intra prediction for HEVC encoder. Specifies the
> + constrained intra prediction in which intra largest coding unit (LCU)
> + prediction is performed by using residual data and decoded samples of
> + neighboring intra LCU only. Setting the value to 1 enables constant intra
> + prediction and setting the value to 0 disables constant inta prediction.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_WAVEFRONT (boolean)``
> + Indicates wavefront parallel processing for HEVC encoder. Setting it to 0
> + disables the feature and setting it to 1 enables the wavefront parallel
> + processing.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_GENERAL_PB (boolean)``
> + Setting the value to 1 enables combination of P and B frame for HEVC
> + encoder.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_TEMPORAL_ID (boolean)``
> + Indicates temporal identifier for HEVC encoder which is enabled by
> + setting the value to 1.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_STRONG_SMOOTHING (boolean)``
> + Indicates bi-linear interpolation is conditionally used in the intra
> + prediction filtering process in the CVS when set to 1. Indicates bi-linear
> + interpolation is not used in the CVS when set to 0.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_MAX_NUM_MERGE_MV_MINUS1 (integer)``
> + Indicates maximum number of merge candidate motion vectors.
> + Values are from zero to four.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_TMV_PREDICTION (boolean)``
> + Indicates temporal motion vector prediction for HEVC encoder. Setting it to
> + 1 enables the prediction. Setting it to 0 disables the prediction.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_WITHOUT_STARTCODE (boolean)``
> + Specifies if HEVC generates a stream with a size of the length field
> + instead of start code pattern. The size of the length field is configurable
> + through the V4L2_CID_MPEG_VIDEO_HEVC_SIZE_OF_LENGTH_FIELD control. Setting
> + the value to 0 disables encoding without startcode pattern. Setting the
> + value to 1 will enables encoding without startcode pattern.
> +
> +.. _v4l2-hevc-size-of-length-field:
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_SIZE_OF_LENGTH_FIELD``
> +(enum)
> +
> +enum v4l2_mpeg_video_hevc_size_of_length_field -
> + Indicates the size of length field.
> + This is valid when encoding WITHOUT_STARTCODE_ENABLE is enabled.
> +
> +.. 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_SIZE_0``
> + - Generate start code pattern (Normal).
> + * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_1``
> + - Generate size of length field instead of start code pattern and length is 1.
> + * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_2``
> + - Generate size of length field instead of start code pattern and length is 2.
> + * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_4``
> + - Generate size of length field instead of start code pattern and length is 4.
> +
> +.. raw:: latex
> +
> + \end{adjustbox}
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L0_BR (integer)``
> + Indicates bit rate for hierarchical coding layer 0 for HEVC encoder.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L1_BR (integer)``
> + Indicates bit rate for hierarchical coding layer 1 for HEVC encoder.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L2_BR (integer)``
> + Indicates bit rate for hierarchical coding layer 2 for HEVC encoder.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L3_BR (integer)``
> + Indicates bit rate for hierarchical coding layer 3 for HEVC encoder.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L4_BR (integer)``
> + Indicates bit rate for hierarchical coding layer 4 for HEVC encoder.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L5_BR (integer)``
> + Indicates bit rate for hierarchical coding layer 5 for HEVC encoder.
> +
> +``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L6_BR (integer)``
> + Indicates bit rate for hierarchical coding layer 6 for HEVC encoder.
> +
> +
> +MFC 10.10 MPEG Controls
> +-----------------------
> +
> +The following MPEG class controls deal with MPEG decoding and encoding
> +settings that are specific to the Multi Format Codec 10.10 device present
> +in the S5P and Exynos family of SoCs by Samsung.
> +
> +
> +.. _mfc1010-control-id:
> +
> +MFC 10.10 Control IDs
> +^^^^^^^^^^^^^^^^^^^^^
> +
> +``V4L2_CID_MPEG_MFC10_VIDEO_HEVC_REF_NUMBER_FOR_PFRAMES (integer)``
> + Selects number of P reference pictures required for HEVC encoder.
> + P-Frame can use 1 or 2 frames for reference.
> +
> +``V4L2_CID_MPEG_MFC10_VIDEO_HEVC_PREPEND_SPSPPS_TO_IDR (integer)``
> + Indicates whether to generate SPS and PPS at every IDR. Setting it to 0
> + disables generating SPS and PPS at every IDR. Setting it to one enables
> + generating SPS and PPS at every IDR.
> +
> +
> .. _camera-controls:
>
> Camera Control Reference
>

Regards,

Hans