[libcamera-devel] [PATCH v9 4/8] libcamera: Support passing ColorSpaces to V4L2 video devices

[Laurent Pinchart]

Hi David,

Thank you for the patch.

On Mon, Dec 06, 2021 at 10:50:27AM +0000, David Plowman wrote:
> The ColorSpace from the StreamConfiguration is now handled
> appropriately in the V4L2VideoDevice.
> 
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
> ---
>  include/libcamera/internal/v4l2_videodevice.h |  2 ++
>  src/libcamera/v4l2_videodevice.cpp            | 32 +++++++++++++++++++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/include/libcamera/internal/v4l2_videodevice.h b/include/libcamera/internal/v4l2_videodevice.h
> index 9b2ec3af..6a507a51 100644
> --- a/include/libcamera/internal/v4l2_videodevice.h
> +++ b/include/libcamera/internal/v4l2_videodevice.h
> @@ -21,6 +21,7 @@
>  #include <libcamera/base/signal.h>
>  #include <libcamera/base/unique_fd.h>
>  
> +#include <libcamera/color_space.h>
>  #include <libcamera/framebuffer.h>
>  #include <libcamera/geometry.h>
>  #include <libcamera/pixel_format.h>
> @@ -167,6 +168,7 @@ public:
>  
>  	V4L2PixelFormat fourcc;
>  	Size size;
> +	std::optional<ColorSpace> colorSpace;

Missing #include <optional> (in v4l2_device.h too)

>  
>  	std::array<Plane, 3> planes;
>  	unsigned int planesCount = 0;
> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
> index b4b89e27..80a8c8e4 100644
> --- a/src/libcamera/v4l2_videodevice.cpp
> +++ b/src/libcamera/v4l2_videodevice.cpp
> @@ -383,6 +383,21 @@ bool V4L2BufferCache::Entry::operator==(const FrameBuffer &buffer) const
>   * that identifies the image format pixel encoding scheme.
>   */
>  
> +/**
> + * \var V4L2DeviceFormat::colorSpace
> + * \brief The color space of the pixels
> + *
> + * The color space of the image. When setting the format this may be
> + * unset, in which case the driver gets to use its default color space.

I'm not used to std::optional, it seems to be an elegant way to handle
this.

> + * After being set, this value should contain the color space that
> + * was actually used. If this value is unset, then the color space chosen
> + * by the driver could not be represented by the ColorSpace class (and
> + * should probably be added).
> + *
> + * It is up to the pipeline handler or application to check if the
> + * resulting color space is acceptable.
> + */
> +
>  /**
>   * \var V4L2DeviceFormat::planes
>   * \brief The per-plane memory size information
> @@ -871,6 +886,7 @@ int V4L2VideoDevice::getFormatMultiplane(V4L2DeviceFormat *format)
>  	format->size.height = pix->height;
>  	format->fourcc = V4L2PixelFormat(pix->pixelformat);
>  	format->planesCount = pix->num_planes;
> +	format->colorSpace = toColorSpace(*pix);
>  
>  	for (unsigned int i = 0; i < format->planesCount; ++i) {
>  		format->planes[i].bpl = pix->plane_fmt[i].bytesperline;
> @@ -893,6 +909,12 @@ int V4L2VideoDevice::trySetFormatMultiplane(V4L2DeviceFormat *format, bool set)
>  	pix->num_planes = format->planesCount;
>  	pix->field = V4L2_FIELD_NONE;
>  
> +	ret = fromColorSpace(format->colorSpace, *pix);
> +	if (ret < 0)
> +		LOG(V4L2, Warning)
> +			<< "Setting color space unrecognised by V4L2: "
> +			<< ColorSpace::toString(format->colorSpace);

Should this be moved to fromColorSpace(), or do you expect valid use
cases for calling it on a color space that can't be represented in V4L2
without printing a message ?

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> +
>  	ASSERT(pix->num_planes <= std::size(pix->plane_fmt));
>  
>  	for (unsigned int i = 0; i < pix->num_planes; ++i) {
> @@ -920,6 +942,7 @@ int V4L2VideoDevice::trySetFormatMultiplane(V4L2DeviceFormat *format, bool set)
>  		format->planes[i].bpl = pix->plane_fmt[i].bytesperline;
>  		format->planes[i].size = pix->plane_fmt[i].sizeimage;
>  	}
> +	format->colorSpace = toColorSpace(*pix);
>  
>  	return 0;
>  }
> @@ -943,6 +966,7 @@ int V4L2VideoDevice::getFormatSingleplane(V4L2DeviceFormat *format)
>  	format->planesCount = 1;
>  	format->planes[0].bpl = pix->bytesperline;
>  	format->planes[0].size = pix->sizeimage;
> +	format->colorSpace = toColorSpace(*pix);
>  
>  	return 0;
>  }
> @@ -959,6 +983,13 @@ int V4L2VideoDevice::trySetFormatSingleplane(V4L2DeviceFormat *format, bool set)
>  	pix->pixelformat = format->fourcc;
>  	pix->bytesperline = format->planes[0].bpl;
>  	pix->field = V4L2_FIELD_NONE;
> +
> +	ret = fromColorSpace(format->colorSpace, *pix);
> +	if (ret < 0)
> +		LOG(V4L2, Warning)
> +			<< "Set color space unrecognised by V4L2: "
> +			<< ColorSpace::toString(format->colorSpace);
> +
>  	ret = ioctl(set ? VIDIOC_S_FMT : VIDIOC_TRY_FMT, &v4l2Format);
>  	if (ret) {
>  		LOG(V4L2, Error)
> @@ -977,6 +1008,7 @@ int V4L2VideoDevice::trySetFormatSingleplane(V4L2DeviceFormat *format, bool set)
>  	format->planesCount = 1;
>  	format->planes[0].bpl = pix->bytesperline;
>  	format->planes[0].size = pix->sizeimage;
> +	format->colorSpace = toColorSpace(*pix);
>  
>  	return 0;
>  }

-- 
Regards,

Laurent Pinchart