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 <ming.qian@xxxxxxx>
> Signed-off-by: Shijie Qin <shijie.qin@xxxxxxx>
> Signed-off-by: Zhou Peng <eagle.zhou@xxxxxxx>
> ---
> 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
