The video capture process involves several processing steps. First the
analog signal is digitized by an
analog-to-digital converter to produce a raw, digital data stream. In the case of
composite video, the
luminance and
chrominance are then separated; this is not necessary for
S-Video
sources. Next, the chrominance is demodulated to produce color
difference video data. At this point, the data may be modified so as to
adjust brightness, contrast, saturation and hue. Finally, the data is
transformed by a
color space converter to generate data in conformance with any of several color space standards, such as
RGB and
YCbCr. Together, these steps constituted
video encoding, because they "encode" an analog video format such as
NTSC or
PAL.
Special electronic circuitry is required to capture video from analog
video sources. At the system level this function is typically performed
by a dedicated
video capture card. Such cards often utilize video decoder integrated circuits to implement the video decoding process.
