Packed RGB formats
&manvol;
Packed RGB formatsPacked RGB formatsDescriptionThese formats are designed to match the pixel formats of
typical PC graphics frame buffers. They occupy 8, 16, 24 or 32 bits
per pixel. These are all packed-pixel formats, meaning all the data
for a pixel lie next to each other in memory.
Bit 7 is the most significant bit.The usage and value of the alpha bits (a) in the ARGB and ABGR formats
(collectively referred to as alpha formats) depend on the device type and
hardware operation. Capture devices
(including capture queues of mem-to-mem devices) fill the alpha component in
memory. When the device outputs an alpha channel the alpha component will
have a meaningful value. Otherwise, when the device doesn't output an alpha
channel but can set the alpha bit to a user-configurable value, the V4L2_CID_ALPHA_COMPONENT
control is used to specify that alpha value, and the alpha component
of all pixels will be set to the value specified by that control. Otherwise
a corresponding format without an alpha component (XRGB or XBGR) must be
used instead of an alpha format.Output devices (including output queues
of mem-to-mem devices and video output overlay
devices) read the alpha component from memory. When the device processes the
alpha channel the alpha component must be filled with meaningful values by
applications. Otherwise a corresponding format without an alpha component
(XRGB or XBGR) must be used instead of an alpha format.The XRGB and XBGR formats contain undefined bits (-). Applications,
devices and drivers must ignore those bits, for both capture and output
devices.V4L2_PIX_FMT_BGR24 4 × 4 pixel
imageByte Order.Each cell is one byte.
start + 0:B00G00R00B01G01R01B02G02R02B03G03R03start + 12:B10G10R10B11G11R11B12G12R12B13G13R13start + 24:B20G20R20B21G21R21B22G22R22B23G23R23start + 36:B30G30R30B31G31R31B32G32R32B33G33R33Formats defined in are
deprecated and must not be used by new drivers. They are documented here for
reference. The meaning of their alpha bits (a) is ill-defined and
interpreted as in either the corresponding ARGB or XRGB format, depending on
the driver.
A test utility to determine which RGB formats a driver
actually supports is available from the LinuxTV v4l-dvb repository.
See &v4l-dvb; for access instructions.