[libcamera-devel] [PATCH v6 4/7] libcamera: Support passing ColorSpaces to V4L2 video devices

[David Plowman]

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            | 53 +++++++++++++++++--
 2 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/include/libcamera/internal/v4l2_videodevice.h b/include/libcamera/internal/v4l2_videodevice.h
index a1c458e4..00bc50e7 100644
--- a/include/libcamera/internal/v4l2_videodevice.h
+++ b/include/libcamera/internal/v4l2_videodevice.h
@@ -20,6 +20,7 @@
 #include <libcamera/base/log.h>
 #include <libcamera/base/signal.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;
 
 	std::array<Plane, 3> planes;
 	unsigned int planesCount = 0;
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index 4f04212d..e03ff8b5 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -370,17 +370,27 @@ bool V4L2BufferCache::Entry::operator==(const FrameBuffer &buffer) const
  * \brief The plane line stride (in bytes)
  */
 
+/**
+ * \var V4L2DeviceFormat::fourcc
+ * \brief The fourcc code describing the pixel encoding scheme
+ *
+ * The fourcc code, as defined by the V4L2 API with the V4L2_PIX_FMT_* macros,
+ * that identifies the image format pixel encoding scheme.
+ */
+
 /**
  * \var V4L2DeviceFormat::size
  * \brief The image size in pixels
  */
 
 /**
- * \var V4L2DeviceFormat::fourcc
- * \brief The fourcc code describing the pixel encoding scheme
+ * \var V4L2DeviceFormat::colorSpace
+ * \brief The color space of the pixels
  *
- * The fourcc code, as defined by the V4L2 API with the V4L2_PIX_FMT_* macros,
- * that identifies the image format pixel encoding scheme.
+ * 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.
+ * After being set, this value should contain the color space that the
+ * was actually used.
  */
 
 /**
@@ -879,6 +889,10 @@ int V4L2VideoDevice::getFormatMultiplane(V4L2DeviceFormat *format)
 	format->fourcc = V4L2PixelFormat(pix->pixelformat);
 	format->planesCount = pix->num_planes;
 
+	format->colorSpace = toColorSpace(*pix);
+	if (!format->colorSpace)
+		LOG(V4L2, Error) << "Retrieved unrecognised color space";
+
 	for (unsigned int i = 0; i < format->planesCount; ++i) {
 		format->planes[i].bpl = pix->plane_fmt[i].bytesperline;
 		format->planes[i].size = pix->plane_fmt[i].sizeimage;
@@ -893,6 +907,9 @@ int V4L2VideoDevice::trySetFormatMultiplane(V4L2DeviceFormat *format, bool set)
 	struct v4l2_pix_format_mplane *pix = &v4l2Format.fmt.pix_mp;
 	int ret;
 
+	if (!format->colorSpace)
+		LOG(V4L2, Warning) << "Setting undefined color space";
+
 	v4l2Format.type = bufferType_;
 	pix->width = format->size.width;
 	pix->height = format->size.height;
@@ -900,6 +917,12 @@ 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);
+
 	ASSERT(pix->num_planes <= std::size(pix->plane_fmt));
 
 	for (unsigned int i = 0; i < pix->num_planes; ++i) {
@@ -928,6 +951,10 @@ int V4L2VideoDevice::trySetFormatMultiplane(V4L2DeviceFormat *format, bool set)
 		format->planes[i].size = pix->plane_fmt[i].sizeimage;
 	}
 
+	format->colorSpace = toColorSpace(*pix);
+	if (!format->colorSpace)
+		LOG(V4L2, Warning) << "Unrecognised color space has been set";
+
 	return 0;
 }
 
@@ -951,6 +978,10 @@ int V4L2VideoDevice::getFormatSingleplane(V4L2DeviceFormat *format)
 	format->planes[0].bpl = pix->bytesperline;
 	format->planes[0].size = pix->sizeimage;
 
+	format->colorSpace = toColorSpace(*pix);
+	if (!format->colorSpace)
+		LOG(V4L2, Error) << "Retrieved unrecognised color space";
+
 	return 0;
 }
 
@@ -960,12 +991,22 @@ int V4L2VideoDevice::trySetFormatSingleplane(V4L2DeviceFormat *format, bool set)
 	struct v4l2_pix_format *pix = &v4l2Format.fmt.pix;
 	int ret;
 
+	if (!format->colorSpace)
+		LOG(V4L2, Error) << "Trying to set unrecognised color space";
+
 	v4l2Format.type = bufferType_;
 	pix->width = format->size.width;
 	pix->height = format->size.height;
 	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)
@@ -985,6 +1026,10 @@ int V4L2VideoDevice::trySetFormatSingleplane(V4L2DeviceFormat *format, bool set)
 	format->planes[0].bpl = pix->bytesperline;
 	format->planes[0].size = pix->sizeimage;
 
+	format->colorSpace = toColorSpace(*pix);
+	if (!format->colorSpace)
+		LOG(V4L2, Error) << "Undefined color space has been set";
+
 	return 0;
 }
 
-- 
2.20.1