2021-07-20 02:07:44

by Ming Qian

Subject: [PATCH v4 02/13] media: v4l: add some definition of v4l2 colorspace/xfer_func/ycbcr_encoding

Some definition of colorspace/xfer_func/ycbcr_encoding
are defined in ISO, but missed in V4L2,
so add some definition according VPU driver's requirement

Signed-off-by: Ming Qian <[email protected]>
Signed-off-by: Shijie Qin <[email protected]>
Signed-off-by: Zhou Peng <[email protected]>
---
include/uapi/linux/videodev2.h | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)

diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 534eaa4d39bc..545f2c329bc9 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -247,6 +247,12 @@ enum v4l2_colorspace {

/* DCI-P3 colorspace, used by cinema projectors */
V4L2_COLORSPACE_DCI_P3 = 12,
+
+ /* Generic film (colour filters using Illuminant C) */
+ V4L2_COLORSPACE_GENERIC_FILM = 13,
+
+ /* SMPTE ST 428-1 */
+ V4L2_COLORSPACE_ST428 = 14,
};

/*
@@ -276,6 +282,20 @@ enum v4l2_xfer_func {
* V4L2_COLORSPACE_RAW: V4L2_XFER_FUNC_NONE
*
* V4L2_COLORSPACE_DCI_P3: V4L2_XFER_FUNC_DCI_P3
+ *
+ * V4L2_XFER_FUNC_LINEAR: Linear transfer characteristics
+ *
+ * V4L2_XFER_FUNC_GAMMA22: Assumed display gamma 2.2
+ *
+ * V4L2_XFER_FUNC_GAMMA28: Assumed display gamma 2.8
+ *
+ * V4L2_XFER_FUNC_HLG: STD-B67, Rec. ITU-R BT.2100-2 hybrid-log-gamma
+ *
+ * V4L2_XFER_FUNC_XVYCC: IEC 61966-2-4
+ *
+ * V4L2_XFER_FUNC_BT1361: Rec. ITU-R BT.1361-0 extended colour gamut
+ *
+ * V4L2_XFER_FUNC_ST428: SMPTE ST 428-1
*/
V4L2_XFER_FUNC_DEFAULT = 0,
V4L2_XFER_FUNC_709 = 1,
@@ -285,6 +305,13 @@ enum v4l2_xfer_func {
V4L2_XFER_FUNC_NONE = 5,
V4L2_XFER_FUNC_DCI_P3 = 6,
V4L2_XFER_FUNC_SMPTE2084 = 7,
+ V4L2_XFER_FUNC_LINEAR = 8,
+ V4L2_XFER_FUNC_GAMMA22 = 9,
+ V4L2_XFER_FUNC_GAMMA28 = 10,
+ V4L2_XFER_FUNC_HLG = 11,
+ V4L2_XFER_FUNC_XVYCC = 12,
+ V4L2_XFER_FUNC_BT1361 = 13,
+ V4L2_XFER_FUNC_ST428 = 14,
};

/*
@@ -345,6 +372,9 @@ enum v4l2_ycbcr_encoding {

/* SMPTE 240M -- Obsolete HDTV */
V4L2_YCBCR_ENC_SMPTE240M = 8,
+
+ /* KR=0.30, KB=0.11 or equivalent */
+ V4L2_YCBCR_ENC_BT470_6M = 9,
};

/*
--
2.32.0

2021-07-21 10:19:02

by Hans Verkuil

Subject: Re: [PATCH v4 02/13] media: v4l: add some definition of v4l2 colorspace/xfer_func/ycbcr_encoding

On 20/07/2021 03:43, Ming Qian wrote:
> Some definition of colorspace/xfer_func/ycbcr_encoding
> are defined in ISO, but missed in V4L2,
> so add some definition according VPU driver's requirement
>
> Signed-off-by: Ming Qian <[email protected]>
> Signed-off-by: Shijie Qin <[email protected]>
> Signed-off-by: Zhou Peng <[email protected]>
> ---
> include/uapi/linux/videodev2.h | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 534eaa4d39bc..545f2c329bc9 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -247,6 +247,12 @@ enum v4l2_colorspace {
>
> /* DCI-P3 colorspace, used by cinema projectors */
> V4L2_COLORSPACE_DCI_P3 = 12,
> +
> + /* Generic film (colour filters using Illuminant C) */
> + V4L2_COLORSPACE_GENERIC_FILM = 13,
> +
> + /* SMPTE ST 428-1 */
> + V4L2_COLORSPACE_ST428 = 14,
> };
>
> /*
> @@ -276,6 +282,20 @@ enum v4l2_xfer_func {
> * V4L2_COLORSPACE_RAW: V4L2_XFER_FUNC_NONE
> *
> * V4L2_COLORSPACE_DCI_P3: V4L2_XFER_FUNC_DCI_P3
> + *
> + * V4L2_XFER_FUNC_LINEAR: Linear transfer characteristics

This exists already: V4L2_XFER_FUNC_NONE

> + *
> + * V4L2_XFER_FUNC_GAMMA22: Assumed display gamma 2.2
> + *
> + * V4L2_XFER_FUNC_GAMMA28: Assumed display gamma 2.8
> + *
> + * V4L2_XFER_FUNC_HLG: STD-B67, Rec. ITU-R BT.2100-2 hybrid-log-gamma
> + *
> + * V4L2_XFER_FUNC_XVYCC: IEC 61966-2-4

This exists already, it is signaled through V4L2_YCBCR_ENC_XV709 and
V4L2_YCBCR_ENC_XV601. It's not actually a different transfer function,
it's the YCbCr encoding that's different (the transfer function is still
V4L2_XFER_FUNC_709).

> + *
> + * V4L2_XFER_FUNC_BT1361: Rec. ITU-R BT.1361-0 extended colour gamut
> + *
> + * V4L2_XFER_FUNC_ST428: SMPTE ST 428-1
> */
> V4L2_XFER_FUNC_DEFAULT = 0,
> V4L2_XFER_FUNC_709 = 1,
> @@ -285,6 +305,13 @@ enum v4l2_xfer_func {
> V4L2_XFER_FUNC_NONE = 5,
> V4L2_XFER_FUNC_DCI_P3 = 6,
> V4L2_XFER_FUNC_SMPTE2084 = 7,
> + V4L2_XFER_FUNC_LINEAR = 8,
> + V4L2_XFER_FUNC_GAMMA22 = 9,
> + V4L2_XFER_FUNC_GAMMA28 = 10,
> + V4L2_XFER_FUNC_HLG = 11,
> + V4L2_XFER_FUNC_XVYCC = 12,
> + V4L2_XFER_FUNC_BT1361 = 13,

This appears to be a variant of xvYCC, it should probably be a YCBCR_ENC variant
since the transfer function defined in bt.1361 is REC709.

> + V4L2_XFER_FUNC_ST428 = 14,

Not sure what this one is about.

> };
>
> /*
> @@ -345,6 +372,9 @@ enum v4l2_ycbcr_encoding {
>
> /* SMPTE 240M -- Obsolete HDTV */
> V4L2_YCBCR_ENC_SMPTE240M = 8,
> +
> + /* KR=0.30, KB=0.11 or equivalent */
> + V4L2_YCBCR_ENC_BT470_6M = 9,
> };
>
> /*
>

I'm not opposed to this, but it has to be documented in
Documentation/userspace-api/media/v4l/colorspaces-details.rst.

I would recommend for an initial submission to only add those new colorimetries
that are actually needed, and others can be added later. uAPI additions take a
lot of time, esp. getting the documentation correct.

Regards,

Hans