From f6a5cb1be894468cdc69ec557d47f40c28f64642 Mon Sep 17 00:00:00 2001 From: Antti Koskipaa Date: Wed, 23 Jun 2010 05:03:42 -0300 Subject: [media] v4l: v4l2_subdev userspace crop API This patch adds the VIDIOC_SUBDEV_S_CROP and G_CROP ioctls to the userland API. CROPCAP is not implemented because it's redundant. Signed-off-by: Antti Koskipaa Signed-off-by: Laurent Pinchart Acked-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/DocBook/v4l/dev-subdev.xml | 33 +++++ Documentation/DocBook/v4l/v4l2.xml | 1 + Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml | 155 +++++++++++++++++++++ 3 files changed, 189 insertions(+) create mode 100644 Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml (limited to 'Documentation/DocBook/v4l') diff --git a/Documentation/DocBook/v4l/dev-subdev.xml b/Documentation/DocBook/v4l/dev-subdev.xml index fc62e65f45ef..e9eb8af0f303 100644 --- a/Documentation/DocBook/v4l/dev-subdev.xml +++ b/Documentation/DocBook/v4l/dev-subdev.xml @@ -275,6 +275,39 @@ +
+ Cropping and scaling + + Many sub-devices support cropping frames on their input or output + pads (or possible even on both). Cropping is used to select the area of + interest in an image, typically on a video sensor or video decoder. It can + also be used as part of digital zoom implementations to select the area of + the image that will be scaled up. + + Crop settings are defined by a crop rectangle and represented in a + &v4l2-rect; by the coordinates of the top left corner and the rectangle + size. Both the coordinates and sizes are expressed in pixels. + + The crop rectangle is retrieved and set using the + &VIDIOC-SUBDEV-G-CROP; and &VIDIOC-SUBDEV-S-CROP; ioctls. Like for pad + formats, drivers store try and active crop rectangles. The format + negotiation mechanism applies to crop settings as well. + + On input pads, cropping is applied relatively to the current pad + format. The pad format represents the image size as received by the + sub-device from the previous block in the pipeline, and the crop rectangle + represents the sub-image that will be transmitted further inside the + sub-device for processing. The crop rectangle be entirely containted + inside the input image size. + + Input crop rectangle are reset to their default value when the input + image format is modified. Drivers should use the input image size as the + crop rectangle default value, but hardware requirements may prevent this. + + + Cropping behaviour on output pads is not defined. + +
&sub-subdev-formats; diff --git a/Documentation/DocBook/v4l/v4l2.xml b/Documentation/DocBook/v4l/v4l2.xml index a436716ef3bc..3a6e3b5c0944 100644 --- a/Documentation/DocBook/v4l/v4l2.xml +++ b/Documentation/DocBook/v4l/v4l2.xml @@ -510,6 +510,7 @@ and discussions on the V4L mailing list. &sub-subdev-enum-frame-interval; &sub-subdev-enum-frame-size; &sub-subdev-enum-mbus-code; + &sub-subdev-g-crop; &sub-subdev-g-fmt; &sub-subdev-g-frame-interval; &sub-subscribe-event; diff --git a/Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml b/Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml new file mode 100644 index 000000000000..06197323a8cc --- /dev/null +++ b/Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml @@ -0,0 +1,155 @@ + + + ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP + &manvol; + + + + VIDIOC_SUBDEV_G_CROP + VIDIOC_SUBDEV_S_CROP + Get or set the crop rectangle on a subdev pad + + + + + + int ioctl + int fd + int request + struct v4l2_subdev_crop *argp + + + + + int ioctl + int fd + int request + const struct v4l2_subdev_crop *argp + + + + + + Arguments + + + + fd + + &fd; + + + + request + + VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP + + + + argp + + + + + + + + + Description + + + Experimental + This is an experimental + interface and may change in the future. + + + To retrieve the current crop rectangle applications set the + pad field of a &v4l2-subdev-crop; to the + desired pad number as reported by the media API and the + which field to + V4L2_SUBDEV_FORMAT_ACTIVE. They then call the + VIDIOC_SUBDEV_G_CROP ioctl with a pointer to this + structure. The driver fills the members of the rect + field or returns &EINVAL; if the input arguments are invalid, or if cropping + is not supported on the given pad. + + To change the current crop rectangle applications set both the + pad and which fields + and all members of the rect field. They then call + the VIDIOC_SUBDEV_S_CROP ioctl with a pointer to this + structure. The driver verifies the requested crop rectangle, adjusts it + based on the hardware capabilities and configures the device. Upon return + the &v4l2-subdev-crop; contains the current format as would be returned + by a VIDIOC_SUBDEV_G_CROP call. + + Applications can query the device capabilities by setting the + which to + V4L2_SUBDEV_FORMAT_TRY. When set, 'try' crop + rectangles are not applied to the device by the driver, but are mangled + exactly as active crop rectangles and stored in the sub-device file handle. + Two applications querying the same sub-device would thus not interact with + each other. + + Drivers must not return an error solely because the requested crop + rectangle doesn't match the device capabilities. They must instead modify + the rectangle to match what the hardware can provide. The modified format + should be as close as possible to the original request. + + + struct <structname>v4l2_subdev_crop</structname> + + &cs-str; + + + __u32 + pad + Pad number as reported by the media framework. + + + __u32 + which + Crop rectangle to get or set, from + &v4l2-subdev-format-whence;. + + + &v4l2-rect; + rect + Crop rectangle boundaries, in pixels. + + + __u32 + reserved[8] + Reserved for future extensions. Applications and drivers must + set the array to zero. + + + +
+ + + + &return-value; + + + + EBUSY + + The crop rectangle can't be changed because the pad is currently + busy. This can be caused, for instance, by an active video stream on + the pad. The ioctl must not be retried without performing another + action to fix the problem first. Only returned by + VIDIOC_SUBDEV_S_CROP + + + + EINVAL + + The &v4l2-subdev-crop; pad + references a non-existing pad, the which + field references a non-existing format, or cropping is not supported + on the given subdev pad. + + + + + -- cgit v1.2.3