ioctl VIDIOC_ENUM_FRAMESIZES &manvol; VIDIOC_ENUM_FRAMESIZES Enumerate frame sizes int ioctl int fd int request struct v4l2_frmsizeenum *argp fd &fd; request VIDIOC_ENUM_FRAMESIZES argp Pointer to a &v4l2-frmsizeenum; that contains an index and pixel format and receives a frame width and height. This ioctl allows applications to enumerate all frame sizes (&ie; width and height in pixels) that the device supports for the given pixel format. The supported pixel formats can be obtained by using the &VIDIOC-ENUM-FMT; function. The return value and the content of the v4l2_frmsizeenum.type field depend on the type of frame sizes the device supports. Here are the semantics of the function for the different cases: Discrete: The function returns success if the given index value (zero-based) is valid. The application should increase the index by one for each call until EINVAL is returned. The v4l2_frmsizeenum.type field is set to V4L2_FRMSIZE_TYPE_DISCRETE by the driver. Of the union only the discrete member is valid. Step-wise: The function returns success if the given index value is zero and EINVAL for any other index value. The v4l2_frmsizeenum.type field is set to V4L2_FRMSIZE_TYPE_STEPWISE by the driver. Of the union only the stepwise member is valid. Continuous: This is a special case of the step-wise type above. The function returns success if the given index value is zero and EINVAL for any other index value. The v4l2_frmsizeenum.type field is set to V4L2_FRMSIZE_TYPE_CONTINUOUS by the driver. Of the union only the stepwise member is valid and the step_width and step_height values are set to 1. When the application calls the function with index zero, it must check the type field to determine the type of frame size enumeration the device supports. Only for the V4L2_FRMSIZE_TYPE_DISCRETE type does it make sense to increase the index value to receive more frame sizes. Note that the order in which the frame sizes are returned has no special meaning. In particular does it not say anything about potential default format sizes. Applications can assume that the enumeration data does not change without any interaction from the application itself. This means that the enumeration data is consistent if the application does not perform any other ioctl calls while it runs the frame size enumeration. In the structs below, IN denotes a value that has to be filled in by the application, OUT denotes values that the driver fills in. The application should zero out all members except for the IN fields. &cs-str; __u32 width Width of the frame [pixel]. __u32 height Height of the frame [pixel]. &cs-str; __u32 min_width Minimum frame width [pixel]. __u32 max_width Maximum frame width [pixel]. __u32 step_width Frame width step size [pixel]. __u32 min_height Minimum frame height [pixel]. __u32 max_height Maximum frame height [pixel]. __u32 step_height Frame height step size [pixel]. __u32 index IN: Index of the given frame size in the enumeration. __u32 pixel_format IN: Pixel format for which the frame sizes are enumerated. __u32 type OUT: Frame size type the device supports. union OUT: Frame size with the given index. &v4l2-frmsize-discrete; discrete &v4l2-frmsize-stepwise; stepwise __u32 reserved[2] Reserved space for future use. &cs-def; V4L2_FRMSIZE_TYPE_DISCRETE 1 Discrete frame size. V4L2_FRMSIZE_TYPE_CONTINUOUS 2 Continuous frame size. V4L2_FRMSIZE_TYPE_STEPWISE 3 Step-wise defined frame size. &return-value;