[libcamera-devel,v5,3/7] libcamera: Convert between ColorSpace class and V4L2 formats

14460 diff mbox series

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@raspberrypi.com>
---
 include/libcamera/internal/v4l2_device.h |   7 +
 src/libcamera/v4l2_device.cpp            | 171 +++++++++++++++++++++++
 2 files changed, 178 insertions(+)

Hi David,

Quoting David Plowman (2021-11-04 13:58:01)
> 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@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..24fc4984 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 toColorSpace(const T &v4l2Format);
> +
> +       template<typename T>
> +       static int fromColorSpace(const 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..34ec2bf3 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> v4l2ToColorSpace = {
> +       { 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> 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::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 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::toColorSpace(const T &v4l2Format)
> +{
> +       ColorSpace colorSpace;
> +
> +       auto itColor = v4l2ToColorSpace.find(v4l2Format.colorspace);
> +       if (itColor != v4l2ToColorSpace.end())
> +               colorSpace = itColor->second;
> +
> +       auto itYcbcrEncoding = v4l2ToYcbcrEncoding.find(v4l2Format.ycbcr_enc);
> +       if (itYcbcrEncoding != v4l2ToYcbcrEncoding.end())
> +               colorSpace.ycbcrEncoding = itYcbcrEncoding->second;
> +
> +       auto itTransfer = v4l2ToTransferFunction.find(v4l2Format.xfer_func);
> +       if (itTransfer != v4l2ToTransferFunction.end())
> +               colorSpace.transferFunction = itTransfer->second;
> +
> +       auto itRange = v4l2ToRange.find(v4l2Format.quantization);
> +       if (itRange != v4l2ToRange.end())
> +               colorSpace.range = itRange->second;
> +
> +       return colorSpace;
> +}
> +
> +template ColorSpace V4L2Device::toColorSpace(const struct v4l2_pix_format &);
> +template ColorSpace V4L2Device::toColorSpace(const struct v4l2_pix_format_mplane &);
> +template 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.
> + *
> + * \return 0 on success or a negative error code otherwise

We normally consider a 'negative error code' to be an errno...

> + */
> +template<typename T>
> +int V4L2Device::fromColorSpace(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(colorSpaceToV4l2.begin(), colorSpaceToV4l2.end(),
> +                                   [&colorSpace](const auto &item) {
> +                                           return colorSpace == item.first;
> +                                   });
> +       if (itColor != colorSpaceToV4l2.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 = primariesToV4l2.find(colorSpace.primaries);
> +       if (itPrimaries != primariesToV4l2.end())
> +               v4l2Format.colorspace = itPrimaries->second;
> +       else
> +               ret = -1;

So this now represents
  EPERM 1 Operation not permitted

Is there something more suited to use?
Peraps just -EINVAL?

Same for the others below of course.

> +
> +       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 ColorSpace &, struct v4l2_pix_format &);
> +template int V4L2Device::fromColorSpace(const ColorSpace &, struct v4l2_pix_format_mplane &);
> +template int V4L2Device::fromColorSpace(const ColorSpace &, struct v4l2_mbus_framefmt &);
> +
>  } /* namespace libcamera */
> -- 
> 2.20.1
>