ViewCast Osprey PCI, Руководство пользователя

Страница: 86 / 126

AVStream Driver Reference Information
80 ViewCast
you are streaming video or capturing to file you will not see numbers this high. If you are encoding
video, you may see high CPU utilization, but much or most of it will be from the encoder rather than
the driver.
Video standards and sizes
Video standard refers to whether the video signal format is NTSC, PAL, or SECAM. Depending on the
exact product version you have, some or all of the following standards will be available:
525-line formats:

NTSC-M
– North America

NTSC-J
– Japan
625-line formats:

PAL-B, D, G, H, I, M, N
– many countries in Europe and elsewhere. B, D, G, H, and I refer to five
nearly identical subformats.
Full-sized NTSC-M and NTSC-J have 525 lines total, 480 lines visible, per frame and a display rate of
59.94 fields per second, or 29.97 interlaced frames per second. Although capture-to-PC applications
normally use only 480 video lines, the full NTSC frame actually contains 485 video lines, and the
AVStream driver provides a control to capture all 485 lines. The control is located on the RefSize
property tab.
Full-sized PAL and SECAM have 625 lines total, 576 lines visible, per frame and a display rate of 50
fields per second, or 25 interlaced frames per second.
The standard frame sizes are different for NTSC and PAL. For example, the half-frame size in pixels is
360 x 240 for NTSC, and 360 x 288 for PAL. The driver automatically adjusts the reference size and
default size for the video standard you are using.
Note: The Osprey 300 always uses CCIR-601 horizontal proportioning, which is based on a 720-pixel
full line width.
Color Formats
The Color Format is the arrangement of data bits representing the colors of each pixel. For example,
in the RGB555 format, each pixel of data is stored as 5 bits of red, 5 bits of green, and 5 bits of blue
color information.
Video delivered by the Osprey board to the system is in uncompressed format. It is possible to
compress the video at a subsequent stage of processing. However, this dialog field refers specifically
to the uncompressed raw video that the board delivers to the system.
The Osprey AVStream driver supports the following capture pin formats.

YUY2 and UYVY - Each pixel is represented with a total of 2 bytes (16 bits) of data. The data is
encoded as separate data for luminance (intensity) and chrominance (color). This mode is mainly
used as an input to software compressors. See YUV Format Details below.