[libcamera-devel] [RFC PATCH 2/3] libcamera: Support passing ColorSpaces to V4L2 drivers

Naushir Patuck naush at raspberrypi.com
Mon Jun 14 12:56:39 CEST 2021


Hi David.

Thank you for your patch.

On Tue, 8 Jun 2021 at 15:44, David Plowman <david.plowman at raspberrypi.com>
wrote:

> The ColorSpace class is added to the StreamConfiguration, and is now
> passed to V4L2 devices where it is handled appropriately. Note how
> this means that the colour space is configured per-stream (though
> platforms may restrict this).
> ---
>  include/libcamera/internal/v4l2_videodevice.h |   2 +
>  include/libcamera/stream.h                    |   3 +
>  src/libcamera/v4l2_videodevice.cpp            | 112 ++++++++++++++++++
>  3 files changed, 117 insertions(+)
>
> diff --git a/include/libcamera/internal/v4l2_videodevice.h
> b/include/libcamera/internal/v4l2_videodevice.h
> index 7938343b..5122d422 100644
> --- a/include/libcamera/internal/v4l2_videodevice.h
> +++ b/include/libcamera/internal/v4l2_videodevice.h
> @@ -18,6 +18,7 @@
>
>  #include <libcamera/buffer.h>
>  #include <libcamera/class.h>
> +#include <libcamera/color_space.h>
>  #include <libcamera/geometry.h>
>  #include <libcamera/pixel_format.h>
>  #include <libcamera/signal.h>
> @@ -162,6 +163,7 @@ public:
>
>         V4L2PixelFormat fourcc;
>         Size size;
> +       ColorSpace colorSpace;
>
>         std::array<Plane, 3> planes;
>         unsigned int planesCount = 0;
> diff --git a/include/libcamera/stream.h b/include/libcamera/stream.h
> index bb47c390..f79c6987 100644
> --- a/include/libcamera/stream.h
> +++ b/include/libcamera/stream.h
> @@ -13,6 +13,7 @@
>  #include <vector>
>
>  #include <libcamera/buffer.h>
> +#include <libcamera/color_space.h>
>  #include <libcamera/geometry.h>
>  #include <libcamera/pixel_format.h>
>
> @@ -47,6 +48,8 @@ struct StreamConfiguration {
>
>         unsigned int bufferCount;
>
> +       ColorSpace colorSpace;
> +
>         Stream *stream() const { return stream_; }
>         void setStream(Stream *stream) { stream_ = stream; }
>         const StreamFormats &formats() const { return formats_; }
> diff --git a/src/libcamera/v4l2_videodevice.cpp
> b/src/libcamera/v4l2_videodevice.cpp
> index 12c09dc7..d606f81d 100644
> --- a/src/libcamera/v4l2_videodevice.cpp
> +++ b/src/libcamera/v4l2_videodevice.cpp
> @@ -730,6 +730,114 @@ int V4L2VideoDevice::getFormat(V4L2DeviceFormat
> *format)
>                 return getFormatSingleplane(format);
>  }
>
> +static const std::vector<std::pair<ColorSpace, v4l2_colorspace>>
> colorSpaceToV4l2 = {
> +       { ColorSpace::RAW, V4L2_COLORSPACE_RAW },
> +       { ColorSpace::JFIF, V4L2_COLORSPACE_JPEG },
> +       { ColorSpace::SMPTE170M, V4L2_COLORSPACE_SMPTE170M },
> +       { ColorSpace::REC709, V4L2_COLORSPACE_REC709 },
> +       { ColorSpace::REC2020, V4L2_COLORSPACE_BT2020 },
> +};
> +
> +static const std::map<ColorSpace::Encoding, v4l2_ycbcr_encoding>
> encodingToV4l2 = {
> +       { ColorSpace::Encoding::REC601, V4L2_YCBCR_ENC_601 },
> +       { ColorSpace::Encoding::REC709, V4L2_YCBCR_ENC_709 },
> +       { ColorSpace::Encoding::REC2020, V4L2_YCBCR_ENC_BT2020 },
> +};
> +
> +static const std::map<ColorSpace::TransferFunction, v4l2_xfer_func>
> transferFunctionToV4l2 = {
> +       { ColorSpace::TransferFunction::IDENTITY, 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 },
> +};
> +
> +template<typename T>
> +static void setColorSpace(const ColorSpace &colorSpace, T &v4l2PixFormat)
>

Could you expand on why this (and below) needs to be templated?


> +{
> +       if (!colorSpace.isFullyDefined())
> +               LOG(V4L2, Warning) << "Setting non-fully defined colour
> space"
> +                                  << colorSpace.toString();
> +
> +       v4l2PixFormat.colorspace = V4L2_COLORSPACE_DEFAULT;
> +       v4l2PixFormat.ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT;
> +       v4l2PixFormat.xfer_func = V4L2_XFER_FUNC_DEFAULT;
> +       v4l2PixFormat.quantization = V4L2_QUANTIZATION_DEFAULT;
> +
> +       auto it_color = std::find_if(colorSpaceToV4l2.begin(),
> colorSpaceToV4l2.end(),
> +                                    [&colorSpace](const
> std::pair<ColorSpace, v4l2_colorspace> &item) { return colorSpace ==
> item.first; });
>

Could you use a map for colorSpaceToV4l2 like you do for the others?

Regards,
Naush


> +       if (it_color != colorSpaceToV4l2.end())
> +               v4l2PixFormat.colorspace = it_color->second;
> +
> +       auto it_encoding = encodingToV4l2.find(colorSpace.encoding);
> +       if (it_encoding != encodingToV4l2.end())
> +               v4l2PixFormat.ycbcr_enc = it_encoding->second;
> +
> +       auto it_transfer =
> transferFunctionToV4l2.find(colorSpace.transferFunction);
> +       if (it_transfer != transferFunctionToV4l2.end())
> +               v4l2PixFormat.xfer_func = it_transfer->second;
> +
> +       auto it_range = rangeToV4l2.find(colorSpace.range);
> +       if (it_range != rangeToV4l2.end())
> +               v4l2PixFormat.quantization = it_range->second;
> +}
> +
> +static const std::map<uint32_t, ColorSpace> v4l2ToColorSpace = {
> +       { V4L2_COLORSPACE_RAW, ColorSpace::RAW },
> +       { V4L2_COLORSPACE_JPEG, ColorSpace::JFIF },
> +       { V4L2_COLORSPACE_SRGB, ColorSpace::JFIF },
> +       { V4L2_COLORSPACE_SMPTE170M, ColorSpace::SMPTE170M },
> +       { V4L2_COLORSPACE_REC709, ColorSpace::REC709 },
> +       { V4L2_COLORSPACE_BT2020, ColorSpace::REC2020 },
> +};
> +
> +static const std::map<uint32_t, ColorSpace::Encoding> v4l2ToEncoding = {
> +       { V4L2_YCBCR_ENC_601, ColorSpace::Encoding::REC601 },
> +       { V4L2_YCBCR_ENC_709, ColorSpace::Encoding::REC709 },
> +       { V4L2_YCBCR_ENC_BT2020, ColorSpace::Encoding::REC2020 },
> +};
> +
> +static const std::map<uint32_t, ColorSpace::TransferFunction>
> v4l2ToTransferFunction = {
> +       { V4L2_XFER_FUNC_NONE, ColorSpace::TransferFunction::IDENTITY },
> +       { 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 },
> +};
> +
> +template<typename T>
> +ColorSpace getColorSpace(const T &v4l2PixFormat)
> +{
> +       ColorSpace colorSpace;
> +
> +       auto it_color = v4l2ToColorSpace.find(v4l2PixFormat.colorspace);
> +       if (it_color != v4l2ToColorSpace.end())
> +               colorSpace = it_color->second;
> +
> +       auto it_encoding = v4l2ToEncoding.find(v4l2PixFormat.ycbcr_enc);
> +       if (it_encoding != v4l2ToEncoding.end())
> +               colorSpace.encoding = it_encoding->second;
> +
> +       auto it_transfer =
> v4l2ToTransferFunction.find(v4l2PixFormat.xfer_func);
> +       if (it_transfer != v4l2ToTransferFunction.end())
> +               colorSpace.transferFunction = it_transfer->second;
> +
> +       auto it_range = v4l2ToRange.find(v4l2PixFormat.quantization);
> +       if (it_range != v4l2ToRange.end())
> +               colorSpace.range = it_range->second;
> +
> +       if (!colorSpace.isFullyDefined())
> +               LOG(V4L2, Warning) << "Returning non-fully defined colour
> space"
> +                                  << colorSpace.toString();
> +       return colorSpace;
> +}
> +
>  /**
>   * \brief Try an image format on the V4L2 video device
>   * \param[inout] format The image format to test applicability to the
> video device
> @@ -839,6 +947,7 @@ int
> V4L2VideoDevice::getFormatMultiplane(V4L2DeviceFormat *format)
>         format->size.width = pix->width;
>         format->size.height = pix->height;
>         format->fourcc = V4L2PixelFormat(pix->pixelformat);
> +       format->colorSpace = getColorSpace(*pix);
>         format->planesCount = pix->num_planes;
>
>         for (unsigned int i = 0; i < format->planesCount; ++i) {
> @@ -861,6 +970,7 @@ int
> V4L2VideoDevice::trySetFormatMultiplane(V4L2DeviceFormat *format, bool set)
>         pix->pixelformat = format->fourcc;
>         pix->num_planes = format->planesCount;
>         pix->field = V4L2_FIELD_NONE;
> +       setColorSpace(format->colorSpace, *pix);
>
>         ASSERT(pix->num_planes <= std::size(pix->plane_fmt));
>
> @@ -909,6 +1019,7 @@ int
> V4L2VideoDevice::getFormatSingleplane(V4L2DeviceFormat *format)
>         format->size.width = pix->width;
>         format->size.height = pix->height;
>         format->fourcc = V4L2PixelFormat(pix->pixelformat);
> +       format->colorSpace = getColorSpace(*pix);
>         format->planesCount = 1;
>         format->planes[0].bpl = pix->bytesperline;
>         format->planes[0].size = pix->sizeimage;
> @@ -928,6 +1039,7 @@ int
> V4L2VideoDevice::trySetFormatSingleplane(V4L2DeviceFormat *format, bool set)
>         pix->pixelformat = format->fourcc;
>         pix->bytesperline = format->planes[0].bpl;
>         pix->field = V4L2_FIELD_NONE;
> +       setColorSpace(format->colorSpace, *pix);
>         ret = ioctl(set ? VIDIOC_S_FMT : VIDIOC_TRY_FMT, &v4l2Format);
>         if (ret) {
>                 LOG(V4L2, Error)
> --
> 2.20.1
>
>
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