The video capture API includes constants, data types, enumerated values, and macros specifying video
capture properties.
The following constants can be passed as function arguments to specify video capture behavior:
CAPTURE_PROPERTY macro
CAPTURE_PROPERTY stores bit maps of information, either retrieved from a video capture
driver and device, or specified by the user application and passed to the video capture library, the
video capture driver, and the device. These bit maps are placed in the four bytes of a
uint32_t value:
- CAPTURE_PROPERTY(a, b, c, d)
- ( (a) << 24 | (b) << 16 | (c) << 8 | (d) )
- Shifts the bits for CAPTURE_PROPERTY_* values.
Video capture behavior
- CAPTURE_FLAG_LATEST_FRAME
- 0x0001
- Get the latest frame and discard all the other queued frames.
- CAPTURE_TIMEOUT_INFINITE
- -1ULL
- Never timeout; wait for frame indefinitely.
- CAPTURE_TIMEOUT_NO_WAIT
- 0
- Return immediately, even if there is no frame.
Interfaces, threads, offsets
The following values specify the video
capture interface type, thread priority, and YUV offsets:
- CAPTURE_PROPERTY_PLANAR_OFFSETS
- CAPTURE_PROPERTY( 'Q', 'P', 'L', 'O' )
- Read/Write [3] int32_t
- The offset from the base address for each of the Y, U, and V components of planar YUV
formats.
- CAPTURE_PROPERTY_THREAD_PRIORITY
- CAPTURE_PROPERTY( 'Q', 'T', 'P', 'R' )
- Read/Write int
- The scheduling priority of the capture thread. The default value
is the priority for the application + 20.
- CAPTURE_PROPERTY_INTERFACE_TYPE
- CAPTURE_PROPERTY('Q','P','I','F')
- Read/Write uint32_t
- The interface type. See "Interface types" below.
Interface types
The following enumerated values are used to specify the interface
type:
enum capture_iface_type {
CAPTURE_IF_PARALLEL = 0,
CAPTURE_IF_MIPI_CSI2,
};
- CAPTURE_IF_PARALLEL
- 0
- The interface is parallel.
- CAPTURE_IF_MIPI_CSI2
- The interface is a MIPI CSI2 interface.
See also "Data bus, and clock and data lane
properties"
Debugging
- CAPTURE_PROPERTY_VERBOSITY
- CAPTURE_PROPERTY( 'Q', 'V', 'B', 'R' )
- Read/Write uint32_t
- Set the log verbosity level. Default is 0.;
increase this value to increase log verbosity for debugging.