[libcamera-devel] [PATCH v3 3/7] libcamera: Convert between ColorSpace class and V4L2 formats
Naushir Patuck
naush at raspberrypi.com
Mon Oct 25 10:04:37 CEST 2021
Hi David,
Thank you for your work.
On Wed, 20 Oct 2021 at 12:08, David Plowman <david.plowman at raspberrypi.com>
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.
>
> Note that we must explicitly instantiate the templates that will be
> needed.
>
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
> ---
> include/libcamera/internal/v4l2_device.h | 7 +
> src/libcamera/v4l2_device.cpp | 171 +++++++++++++++++++++++
> 2 files changed, 178 insertions(+)
>
> diff --git a/include/libcamera/internal/v4l2_device.h
> b/include/libcamera/internal/v4l2_device.h
> index f21bc370..77ea30f6 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 ColorSpace v4l2ToColorSpace(const T &v4l2Format);
> +
> + template<typename T>
> + static int colorSpaceToV4l2(const ColorSpace &colorSpace, T
> &v4l2Format);
>
For consistency with other classes, perhaps these should be renamed to
toColorSpace and fromColorSpace?
I wonder if this implementation should also live in the ColorSpace class?
This would
sort of mirror what the various format classes do. But I have no strong
preference
either w
+
> protected:
> V4L2Device(const std::string &deviceNode);
> ~V4L2Device();
> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> index 9c783c9c..771dc096 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 +733,173 @@ void V4L2Device::eventAvailable()
> frameStart.emit(event.u.frame_sync.frame_sequence);
> }
>
> +static const std::map<uint32_t, ColorSpace> v4l2ToColorSpaceTable = {
> + { V4L2_COLORSPACE_RAW, ColorSpace::Raw },
> + { V4L2_COLORSPACE_JPEG, ColorSpace::Jpeg },
> + { V4L2_COLORSPACE_SRGB, ColorSpace::Jpeg },
> + { V4L2_COLORSPACE_SMPTE170M, ColorSpace::Smpte170m },
> + { V4L2_COLORSPACE_REC709, ColorSpace::Rec709 },
> + { V4L2_COLORSPACE_BT2020, ColorSpace::Rec2020 },
> +};
> +
> +static const std::map<uint32_t, ColorSpace::YcbcrEncoding>
> v4l2ToYcbcrEncodingTable = {
> + { 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>
> v4l2ToTransferFunctionTable = {
> + { 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> v4l2ToRangeTable = {
> + { V4L2_QUANTIZATION_FULL_RANGE, ColorSpace::Range::Full },
> + { V4L2_QUANTIZATION_LIM_RANGE, ColorSpace::Range::Limited },
> +};
> +
> +static const std::vector<std::pair<ColorSpace, v4l2_colorspace>>
> colorSpaceToV4l2Table = {
> + { ColorSpace::Raw, V4L2_COLORSPACE_RAW },
> + { ColorSpace::Jpeg, V4L2_COLORSPACE_JPEG },
> + { ColorSpace::Smpte170m, V4L2_COLORSPACE_SMPTE170M },
> + { ColorSpace::Rec709, V4L2_COLORSPACE_REC709 },
> + { ColorSpace::Rec2020, V4L2_COLORSPACE_BT2020 },
> +};
> +
> +static const std::map<ColorSpace::Primaries, v4l2_colorspace>
> primariesToV4l2Table = {
> + { 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>
> ycbcrEncodingToV4l2Table = {
> + { 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>
> transferFunctionToV4l2Table = {
> + { 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>
> rangeToV4l2Table = {
> + { 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 those are marked as undefined in
> + * the ColorSpace, but other fields are still initialised where possible.
> + * This situation can be detected using the returned value's
> + * ColorSpace::isFullyDefined() method.
> + *
> + * \return The ColorSpace corresponding to the input V4L2 format
> + */
> +template<typename T>
> +ColorSpace V4L2Device::v4l2ToColorSpace(const T &v4l2Format)
> +{
> + ColorSpace colorSpace;
> +
> + auto itColor = v4l2ToColorSpaceTable.find(v4l2Format.colorspace);
> + if (itColor != v4l2ToColorSpaceTable.end())
> + colorSpace = itColor->second;
> +
> + auto itYcbcrEncoding =
> v4l2ToYcbcrEncodingTable.find(v4l2Format.ycbcr_enc);
> + if (itYcbcrEncoding != v4l2ToYcbcrEncodingTable.end())
> + colorSpace.ycbcrEncoding = itYcbcrEncoding->second;
> +
> + auto itTransfer =
> v4l2ToTransferFunctionTable.find(v4l2Format.xfer_func);
> + if (itTransfer != v4l2ToTransferFunctionTable.end())
> + colorSpace.transferFunction = itTransfer->second;
> +
> + auto itRange = v4l2ToRangeTable.find(v4l2Format.quantization);
> + if (itRange != v4l2ToRangeTable.end())
> + colorSpace.range = itRange->second;
> +
> + return colorSpace;
> +}
> +
> +template ColorSpace V4L2Device::v4l2ToColorSpace(const struct
> v4l2_pix_format &);
> +template ColorSpace V4L2Device::v4l2ToColorSpace(const struct
> v4l2_pix_format_mplane &);
> +template ColorSpace V4L2Device::v4l2ToColorSpace(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.
> + *
> + * \return 0 on success or a negative error code otherwise
> + */
> +template<typename T>
> +int V4L2Device::colorSpaceToV4l2(const 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;
> +
> + auto itColor = std::find_if(colorSpaceToV4l2Table.begin(),
> colorSpaceToV4l2Table.end(),
> + [&colorSpace](const auto &item) {
> + return colorSpace ==
> item.first;
> + });
>
You can use std::map::find() here, to cut down on the typing :)
> + if (itColor != colorSpaceToV4l2Table.end()) {
> + v4l2Format.colorspace = itColor->second;
> + 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 = primariesToV4l2Table.find(colorSpace.primaries);
> + if (itPrimaries != primariesToV4l2Table.end())
> + v4l2Format.colorspace = itPrimaries->second;
> + else
> + ret = -1;
> +
> + auto itYcbcrEncoding =
> ycbcrEncodingToV4l2Table.find(colorSpace.ycbcrEncoding);
> + if (itYcbcrEncoding != ycbcrEncodingToV4l2Table.end())
> + v4l2Format.ycbcr_enc = itYcbcrEncoding->second;
> + else
> + ret = -1;
> +
> + auto itTransfer =
> transferFunctionToV4l2Table.find(colorSpace.transferFunction);
> + if (itTransfer != transferFunctionToV4l2Table.end())
> + v4l2Format.xfer_func = itTransfer->second;
> + else
> + ret = -1;
> +
> + auto itRange = rangeToV4l2Table.find(colorSpace.range);
> + if (itRange != rangeToV4l2Table.end())
> + v4l2Format.quantization = itRange->second;
> + else
> + ret = -1;
> +
> + return ret;
> +}
> +
> +template int V4L2Device::colorSpaceToV4l2(const ColorSpace &, struct
> v4l2_pix_format &);
> +template int V4L2Device::colorSpaceToV4l2(const ColorSpace &, struct
> v4l2_pix_format_mplane &);
> +template int V4L2Device::colorSpaceToV4l2(const ColorSpace &, struct
> v4l2_mbus_framefmt &);
> +
> } /* namespace libcamera */
> --
> 2.20.1
>
>
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