Re: [PATCH v5 3/5] v4l: Add HDR10 static metadata controls

[Hans Verkuil]

On 22/03/2021 13:56, Stanimir Varbanov wrote:
> Hi Hans,
> 
> On 3/16/21 2:16 PM, Hans Verkuil wrote:
>> On 09/02/2021 17:24, Stanimir Varbanov wrote:
>>> Introduce Content light level and Mastering display colour
>>> volume Colorimetry compound controls with relevant payload
>>> structures and validation.
>>>
>>> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@xxxxxxxxxx>
>>> ---
>>>  drivers/media/v4l2-core/v4l2-ctrls.c | 67 ++++++++++++++++++++++++++++
>>>  include/media/v4l2-ctrls.h           |  4 ++
>>>  include/uapi/linux/v4l2-controls.h   | 31 +++++++++++++
>>>  include/uapi/linux/videodev2.h       |  3 ++
>>>  4 files changed, 105 insertions(+)
>>>
>>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
>>> index 335cf354f51b..8bd3cf0e1e4f 100644
>>> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
>>> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
>>> @@ -1205,6 +1205,8 @@ const char *v4l2_ctrl_get_name(u32 id)
>>>  	/* Colorimetry controls */
>>>  	/* Keep the order of the 'case's the same as in v4l2-controls.h! */
>>>  	case V4L2_CID_COLORIMETRY_CLASS:	return "Colorimetry Controls";
>>> +	case V4L2_CID_COLORIMETRY_HDR10_CLL_INFO:		return "HDR10 Content Light Info";
>>> +	case V4L2_CID_COLORIMETRY_HDR10_MASTERING_DISPLAY:	return "HDR10 Mastering Display";
>>>  	default:
>>>  		return NULL;
>>>  	}
>>> @@ -1491,6 +1493,12 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
>>>  		*type = V4L2_CTRL_TYPE_AREA;
>>>  		*flags |= V4L2_CTRL_FLAG_READ_ONLY;
>>>  		break;
>>> +	case V4L2_CID_COLORIMETRY_HDR10_CLL_INFO:
>>> +		*type = V4L2_CTRL_TYPE_HDR10_CLL_INFO;
>>> +		break;
>>> +	case V4L2_CID_COLORIMETRY_HDR10_MASTERING_DISPLAY:
>>> +		*type = V4L2_CTRL_TYPE_HDR10_MASTERING_DISPLAY;
>>> +		break;
>>>  	default:
>>>  		*type = V4L2_CTRL_TYPE_INTEGER;
>>>  		break;
>>> @@ -1786,6 +1794,12 @@ static void std_log(const struct v4l2_ctrl *ctrl)
>>>  	case V4L2_CTRL_TYPE_FWHT_PARAMS:
>>>  		pr_cont("FWHT_PARAMS");
>>>  		break;
>>> +	case V4L2_CTRL_TYPE_HDR10_CLL_INFO:
>>> +		pr_cont("HDR10_CLL_INFO");
>>> +		break;
>>> +	case V4L2_CTRL_TYPE_HDR10_MASTERING_DISPLAY:
>>> +		pr_cont("HDR10_MASTERING_DISPLAY");
>>> +		break;
>>>  	default:
>>>  		pr_cont("unknown type %d", ctrl->type);
>>>  		break;
>>> @@ -1838,6 +1852,7 @@ static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx,
>>>  	struct v4l2_ctrl_hevc_sps *p_hevc_sps;
>>>  	struct v4l2_ctrl_hevc_pps *p_hevc_pps;
>>>  	struct v4l2_ctrl_hevc_slice_params *p_hevc_slice_params;
>>> +	struct v4l2_ctrl_hdr10_mastering_display *p_hdr10_mastering;
>>>  	struct v4l2_area *area;
>>>  	void *p = ptr.p + idx * ctrl->elem_size;
>>>  	unsigned int i;
>>> @@ -2133,6 +2148,52 @@ static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx,
>>>  		zero_padding(*p_hevc_slice_params);
>>>  		break;
>>>  
>>> +	case V4L2_CTRL_TYPE_HDR10_CLL_INFO:
>>> +		break;
>>> +
>>> +	case V4L2_CTRL_TYPE_HDR10_MASTERING_DISPLAY:
>>> +		p_hdr10_mastering = p;
>>> +
>>> +		for (i = 0; i < 3; ++i) {
>>> +			if (p_hdr10_mastering->display_primaries_x[i] <
>>> +				V4L2_HDR10_MASTERING_PRIMARIES_X_LOW ||
>>> +			    p_hdr10_mastering->display_primaries_x[i] >
>>> +				V4L2_HDR10_MASTERING_PRIMARIES_X_HIGH ||
>>> +			    p_hdr10_mastering->display_primaries_y[i] <
>>> +				V4L2_HDR10_MASTERING_PRIMARIES_Y_LOW ||
>>> +			    p_hdr10_mastering->display_primaries_y[i] >
>>> +				V4L2_HDR10_MASTERING_PRIMARIES_Y_HIGH)
>>> +				return -EINVAL;
>>> +		}
>>> +
>>> +		if (p_hdr10_mastering->white_point_x <
>>> +			V4L2_HDR10_MASTERING_WHITE_POINT_X_LOW ||
>>> +		    p_hdr10_mastering->white_point_x >
>>> +			V4L2_HDR10_MASTERING_WHITE_POINT_X_HIGH ||
>>> +		    p_hdr10_mastering->white_point_y <
>>> +			V4L2_HDR10_MASTERING_WHITE_POINT_Y_LOW ||
>>> +		    p_hdr10_mastering->white_point_y >
>>> +			V4L2_HDR10_MASTERING_WHITE_POINT_Y_HIGH)
>>> +			return -EINVAL;
>>> +
>>> +		if (p_hdr10_mastering->max_display_mastering_luminance <
>>> +			V4L2_HDR10_MASTERING_MAX_LUMA_LOW ||
>>> +		    p_hdr10_mastering->max_display_mastering_luminance >
>>> +			V4L2_HDR10_MASTERING_MAX_LUMA_HIGH ||
>>> +		    p_hdr10_mastering->min_display_mastering_luminance <
>>> +			V4L2_HDR10_MASTERING_MIN_LUMA_LOW ||
>>> +		    p_hdr10_mastering->min_display_mastering_luminance >
>>> +			V4L2_HDR10_MASTERING_MIN_LUMA_HIGH)
>>> +			return -EINVAL;
>>> +
>>> +		if (p_hdr10_mastering->max_display_mastering_luminance ==
>>> +			V4L2_HDR10_MASTERING_MAX_LUMA_LOW &&
>>> +		    p_hdr10_mastering->min_display_mastering_luminance ==
>>> +			V4L2_HDR10_MASTERING_MIN_LUMA_HIGH)
>>
>> I had to think about this one :-)
>>
>> Isn't it clearer to write:
>>
>> 		if (p_hdr10_mastering->min_display_mastering_luminance >=
>> 		    p_hdr10_mastering->max_display_mastering_luminance)
>>
>> (even though it can't be >, but >= is probably more robust and future proof)
>>
>> And is it indeed invalid if both are the same?
> 
> This what the ITU-T Rec. H.265 spec says:
> 
> "When max_display_mastering_luminance is equal to 50 000,
> min_display_mastering_luminance shall not be equal to 50 000."

OK. Just add a comment explaining that that restriction comes from the
H.265 spec.

Regards,

	Hans

> 
>