[libcamera-devel] [PATCH v6 3/7] libcamera: Convert between ColorSpace class and V4L2 formats
David Plowman
david.plowman at raspberrypi.com
Wed Nov 24 12:08:23 CET 2021
Hi Umang
Thanks for reviewing this!
On Tue, 23 Nov 2021 at 14:49, Umang Jain <umang.jain at ideasonboard.com> wrote:
>
> Hi David,
>
> The patch looks good to me overall, just one comment
>
> On 11/18/21 8:49 PM, David Plowman wrote:
> > These methods are added to the base V4L2Device class so that they can
> > be shared both by the video device class and subdevices.
> >
> > With the ColorSpace class, the color space and related other fields
> > are stored together, corresponding to a number of fields in the
> > various different V4L2 format structures. Template methods are
> > therefore a convenient implementation, and we must explicitly
> > instantiate the templates that will be needed.
> >
> > Note that unset color spaces are converted to requests for the
> > device's "default" color space.
> >
> > Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
> > ---
> > include/libcamera/internal/v4l2_device.h | 7 +
> > src/libcamera/v4l2_device.cpp | 190 +++++++++++++++++++++++
> > 2 files changed, 197 insertions(+)
> >
> > diff --git a/include/libcamera/internal/v4l2_device.h b/include/libcamera/internal/v4l2_device.h
> > index f21bc370..89ff6120 100644
> > --- a/include/libcamera/internal/v4l2_device.h
> > +++ b/include/libcamera/internal/v4l2_device.h
> > @@ -17,6 +17,7 @@
> > #include <libcamera/base/signal.h>
> > #include <libcamera/base/span.h>
> >
> > +#include <libcamera/color_space.h>
> > #include <libcamera/controls.h>
> >
> > namespace libcamera {
> > @@ -44,6 +45,12 @@ public:
> >
> > void updateControlInfo();
> >
> > + template<typename T>
> > + static std::optional<ColorSpace> toColorSpace(const T &v4l2Format);
> > +
> > + template<typename T>
> > + static int fromColorSpace(const std::optional<ColorSpace> &colorSpace, T &v4l2Format);
> > +
> > protected:
> > V4L2Device(const std::string &deviceNode);
> > ~V4L2Device();
> > diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> > index 9c783c9c..4d6985aa 100644
> > --- a/src/libcamera/v4l2_device.cpp
> > +++ b/src/libcamera/v4l2_device.cpp
> > @@ -16,6 +16,8 @@
> > #include <sys/syscall.h>
> > #include <unistd.h>
> >
> > +#include <linux/v4l2-mediabus.h>
> > +
> > #include <libcamera/base/event_notifier.h>
> > #include <libcamera/base/log.h>
> > #include <libcamera/base/utils.h>
> > @@ -731,4 +733,192 @@ void V4L2Device::eventAvailable()
> > frameStart.emit(event.u.frame_sync.frame_sequence);
> > }
> >
> > +static const std::map<uint32_t, ColorSpace> v4l2ToColorSpace = {
> > + { V4L2_COLORSPACE_RAW, ColorSpace::Raw },
> > + { V4L2_COLORSPACE_JPEG, ColorSpace::Jpeg },
> > + { V4L2_COLORSPACE_SRGB, ColorSpace::Srgb },
> > + { V4L2_COLORSPACE_SMPTE170M, ColorSpace::Smpte170m },
> > + { V4L2_COLORSPACE_REC709, ColorSpace::Rec709 },
> > + { V4L2_COLORSPACE_BT2020, ColorSpace::Rec2020 },
> > +};
> > +
> > +static const std::map<uint32_t, ColorSpace::YcbcrEncoding> v4l2ToYcbcrEncoding = {
> > + { V4L2_YCBCR_ENC_601, ColorSpace::YcbcrEncoding::Rec601 },
> > + { V4L2_YCBCR_ENC_709, ColorSpace::YcbcrEncoding::Rec709 },
> > + { V4L2_YCBCR_ENC_BT2020, ColorSpace::YcbcrEncoding::Rec2020 },
> > +};
> > +
> > +static const std::map<uint32_t, ColorSpace::TransferFunction> v4l2ToTransferFunction = {
> > + { V4L2_XFER_FUNC_NONE, ColorSpace::TransferFunction::Linear },
> > + { V4L2_XFER_FUNC_SRGB, ColorSpace::TransferFunction::Srgb },
> > + { V4L2_XFER_FUNC_709, ColorSpace::TransferFunction::Rec709 },
> > +};
> > +
> > +static const std::map<uint32_t, ColorSpace::Range> v4l2ToRange = {
> > + { V4L2_QUANTIZATION_FULL_RANGE, ColorSpace::Range::Full },
> > + { V4L2_QUANTIZATION_LIM_RANGE, ColorSpace::Range::Limited },
> > +};
> > +
> > +static const std::vector<std::pair<ColorSpace, v4l2_colorspace>> colorSpaceToV4l2 = {
> > + { ColorSpace::Raw, V4L2_COLORSPACE_RAW },
> > + { ColorSpace::Jpeg, V4L2_COLORSPACE_JPEG },
> > + { ColorSpace::Srgb, V4L2_COLORSPACE_SRGB },
> > + { ColorSpace::Smpte170m, V4L2_COLORSPACE_SMPTE170M },
> > + { ColorSpace::Rec709, V4L2_COLORSPACE_REC709 },
> > + { ColorSpace::Rec2020, V4L2_COLORSPACE_BT2020 },
> > +};
> > +
> > +static const std::map<ColorSpace::Primaries, v4l2_colorspace> primariesToV4l2 = {
> > + { ColorSpace::Primaries::Raw, V4L2_COLORSPACE_RAW },
> > + { ColorSpace::Primaries::Smpte170m, V4L2_COLORSPACE_SMPTE170M },
> > + { ColorSpace::Primaries::Rec709, V4L2_COLORSPACE_REC709 },
> > + { ColorSpace::Primaries::Rec2020, V4L2_COLORSPACE_BT2020 },
> > +};
> > +
> > +static const std::map<ColorSpace::YcbcrEncoding, v4l2_ycbcr_encoding> ycbcrEncodingToV4l2 = {
> > + { ColorSpace::YcbcrEncoding::Rec601, V4L2_YCBCR_ENC_601 },
> > + { ColorSpace::YcbcrEncoding::Rec709, V4L2_YCBCR_ENC_709 },
> > + { ColorSpace::YcbcrEncoding::Rec2020, V4L2_YCBCR_ENC_BT2020 },
> > +};
> > +
> > +static const std::map<ColorSpace::TransferFunction, v4l2_xfer_func> transferFunctionToV4l2 = {
> > + { ColorSpace::TransferFunction::Linear, V4L2_XFER_FUNC_NONE },
> > + { ColorSpace::TransferFunction::Srgb, V4L2_XFER_FUNC_SRGB },
> > + { ColorSpace::TransferFunction::Rec709, V4L2_XFER_FUNC_709 },
> > +};
> > +
> > +static const std::map<ColorSpace::Range, v4l2_quantization> rangeToV4l2 = {
> > + { ColorSpace::Range::Full, V4L2_QUANTIZATION_FULL_RANGE },
> > + { ColorSpace::Range::Limited, V4L2_QUANTIZATION_LIM_RANGE },
> > +};
> > +
> > +/**
> > + * \brief Convert the color space fields in a V4L2 format to a ColorSpace
> > + * \param[in] v4l2Format A V4L2 format containing color space information
> > + *
> > + * The colorspace, ycbcr_enc, xfer_func and quantization fields within a
> > + * V4L2 format structure are converted to a corresponding ColorSpace.
> > + *
> > + * If any V4L2 fields are not recognised then we return an "unset"
> > + * color space.
> > + *
> > + * \return The ColorSpace corresponding to the input V4L2 format
> > + */
> > +template<typename T>
> > +std::optional<ColorSpace> V4L2Device::toColorSpace(const T &v4l2Format)
> > +{
> > + auto itColor = v4l2ToColorSpace.find(v4l2Format.colorspace);
> > + if (itColor == v4l2ToColorSpace.end())
> > + return std::nullopt;
> > +
> > + /* This sets all the color space fields to the correct "default" values. */
> > + ColorSpace colorSpace = itColor->second;
> > +
> > + if (v4l2Format.ycbcr_enc != V4L2_YCBCR_ENC_DEFAULT) {
> > + auto itYcbcrEncoding = v4l2ToYcbcrEncoding.find(v4l2Format.ycbcr_enc);
> > + if (itYcbcrEncoding == v4l2ToYcbcrEncoding.end())
> > + return std::nullopt;
> > +
> > + colorSpace.ycbcrEncoding = itYcbcrEncoding->second;
> > + }
> > +
> > + if (v4l2Format.xfer_func != V4L2_XFER_FUNC_DEFAULT) {
> > + auto itTransfer = v4l2ToTransferFunction.find(v4l2Format.xfer_func);
> > + if (itTransfer == v4l2ToTransferFunction.end())
> > + return std::nullopt;
> > +
> > + colorSpace.transferFunction = itTransfer->second;
> > + }
> > +
> > + if (v4l2Format.quantization != V4L2_QUANTIZATION_DEFAULT) {
> > + auto itRange = v4l2ToRange.find(v4l2Format.quantization);
> > + if (itRange == v4l2ToRange.end())
> > + return std::nullopt;
> > +
> > + colorSpace.range = itRange->second;
> > + }
> > +
> > + return colorSpace;
> > +}
> > +
> > +template std::optional<ColorSpace> V4L2Device::toColorSpace(const struct v4l2_pix_format &);
> > +template std::optional<ColorSpace> V4L2Device::toColorSpace(const struct v4l2_pix_format_mplane &);
> > +template std::optional<ColorSpace> V4L2Device::toColorSpace(const struct v4l2_mbus_framefmt &);
> > +
> > +/**
> > + * \brief Fill in the color space fields of a V4L2 format from a ColorSpace
> > + * \param[in] colorSpace The ColorSpace to be converted
> > + * \param[out] v4l2Format A V4L2 format containing color space information
> > + *
> > + * The colorspace, ycbcr_enc, xfer_func and quantization fields within a
> > + * V4L2 format structure are filled in from a corresponding ColorSpace.
> > + *
> > + * An error is returned if any of the V4L2 fields do not support the
> > + * value given in the ColorSpace. Such fields are set to the V4L2
> > + * "default" values, but all other fields are still filled in where
> > + * possible.
> > + *
> > + * If the color space is completely unset, "default" V4L2 values are used
> > + * everywhere, so a driver would then choose its preferred color space.
> > + *
> > + * \return 0 on success or a negative error code otherwise
>
> I think we are not returning any error codes (ergo errno here) here.
> All I see -1 returned on error paths.
Just to clarify, are you simply implying a change to the documentation
here, i.e. "\return 0 on success or -1 otherwise" ?
Thanks!
David
>
>
> > + */
> > +template<typename T>
> > +int V4L2Device::fromColorSpace(const std::optional<ColorSpace> &colorSpace, T &v4l2Format)
> > +{
> > + int ret = 0;
> > +
> > + v4l2Format.colorspace = V4L2_COLORSPACE_DEFAULT;
> > + v4l2Format.ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT;
> > + v4l2Format.xfer_func = V4L2_XFER_FUNC_DEFAULT;
> > + v4l2Format.quantization = V4L2_QUANTIZATION_DEFAULT;
> > +
> > + if (!colorSpace)
> > + return ret;
> > +
> > + auto itColor = std::find_if(colorSpaceToV4l2.begin(), colorSpaceToV4l2.end(),
> > + [&colorSpace](const auto &item) {
> > + return colorSpace == item.first;
> > + });
> > + if (itColor != colorSpaceToV4l2.end()) {
> > + v4l2Format.colorspace = itColor->second;
> > + /* Leaving all the other fields as "default" should be fine. */
> > + return ret;
> > + }
> > +
> > + /*
> > + * If the colorSpace doesn't precisely match a standard color space,
> > + * then we must choose a V4L2 colorspace with matching primaries.
> > + */
> > + auto itPrimaries = primariesToV4l2.find(colorSpace->primaries);
> > + if (itPrimaries != primariesToV4l2.end())
> > + v4l2Format.colorspace = itPrimaries->second;
> > + else
> > + ret = -1;
> > +
> > + auto itYcbcrEncoding = ycbcrEncodingToV4l2.find(colorSpace->ycbcrEncoding);
> > + if (itYcbcrEncoding != ycbcrEncodingToV4l2.end())
> > + v4l2Format.ycbcr_enc = itYcbcrEncoding->second;
> > + else
> > + ret = -1;
> > +
> > + auto itTransfer = transferFunctionToV4l2.find(colorSpace->transferFunction);
> > + if (itTransfer != transferFunctionToV4l2.end())
> > + v4l2Format.xfer_func = itTransfer->second;
> > + else
> > + ret = -1;
> > +
> > + auto itRange = rangeToV4l2.find(colorSpace->range);
> > + if (itRange != rangeToV4l2.end())
> > + v4l2Format.quantization = itRange->second;
> > + else
> > + ret = -1;
> > +
> > + return ret;
> > +}
> > +
> > +template int V4L2Device::fromColorSpace(const std::optional<ColorSpace> &, struct v4l2_pix_format &);
> > +template int V4L2Device::fromColorSpace(const std::optional<ColorSpace> &, struct v4l2_pix_format_mplane &);
> > +template int V4L2Device::fromColorSpace(const std::optional<ColorSpace> &, struct v4l2_mbus_framefmt &);
> > +
> > } /* namespace libcamera */
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