Sensoray 2253 Linux - Manual (Page 6)

Basic Operation
When the driver is loaded, there are three video device nodes and one GPIO
char device created in the /dev directory. The video nodes are named
“videoX” where X depends on the number of video devices present in the
system. The first two video device nodes are for video capture/preview and
the third video device node is for video output.
Video Capture and Output Driver
The driver supports Video4Linux 2 (V4L2) ioctls. The V4L2 API is well
documented at the LinuxTV web site
(http://www.linuxtv.org/downloads/v4l-dvb-apis/). V4L2 operation is not
supported for kernels below 2.6.25. The v4l-dvb hg or git tree is not required
(and not recommended) to use this driver.
The three video devices can be used with applications that support V4L2 API.
Video can be captured using uncompressed YUV422 (packed YUYV or UYVY)
or YUV420SP (NV12 semi-planar, Y plane and interleaved CrCb plane) or
encoded in compressed formats JPEG, MPEG4 ASP or H.264 elementary
streams. The MPEG4 or H.264 streams can also be muxed with AAC audio
(with A/V sync) in a MP4 container or a MPEG transport stream. Both capture
devices record video from a single source, and each capture device can be
started, stopped, and configured independently. Some video options cannot
be configured independently, such as interpolation, brightness, hue, contrast,
and saturation.
One example of operation is capturing compressed video to a storage device
while simultaneously previewing the uncompressed video on the display.
Another example is capturing high-bandwidth compressed video to a storage
device while simultaneously streaming low-bandwidth compressed video over
a network interface.
The video output device can play compressed streams containing MPEG4 or
H.264 elementary streams. MP4 muxed fragmented streams or MPEG
transport streams are also supported with A/V sync. MJPEG decoding is not
supported at this time.
There are internal limitations in the device that may prevent use of both input
streams and the output stream simultaneously. It is recommended to limit
use to both input streams simultaneously, or a single input stream and single
output stream simultaneously. The limitation may appear as stuttering video
and audio during playback.
6