VX2000 - Page 3
The unit features a complete set of inputs for connecting a number of devices
to capture video from: S-Video or Composite Video In, stereo audio input, cable
TV/aerial antenna TV input. Last but not least, an IEEE1394 input is there
if you want to connect a DV camcorder. All the connectors except the TV input
are located in the front making connecting/disconnecting cables easier. All
the necessary cables were included in the packaging, so you don’t need
to buy any extra cables to connect your video sources.
The front panel of the XRecorder is shown in the following picture.
As can be seen in this photo, there are three choices of input available
for video capture. From left to
right we have:
- the infra-red remote control detector
- then in turn the
IEEE 1394 DV input
- next are the left
and right sound channels (white and red
- composite video input (yellow RCA plug)
- finally, the S-video input (4-pin DIN plug).
You would connect your external video source device such as a DVD player,
VCR, camera, etc using one of these connections.
The following picture shows the rear panel.
Here we have the power input (5V DC), 75 ohm IEC coaxial input (cable TV antenna),
port which connects to your PC, and on the far right the on/off switch.
The following diagram shows the possible source devices and how they can be
connected to the XRecorder, and the USB connection which is here shown going
to a portable PC.
How a video signal is generated
The three primary colours used in broadcast TV systems are red, green and
blue or RGB for short. The proportions in which they are mixed however is not
equal. The equation 0.30 R' + 0.59 G' + 0.11 B', corresponds to the human eye's
sensitivity to each of the three colours. When combined in these proportions,
they produce one signal, called the luminance signal. In fact, that is how
a black and white TV works. All it shows is the contrast in a picture, without
the colour information. When colour TV came on the scene, one of the criteria
that a colour signal had to still be compatible with black and white
TVs which were still in use. All a black and white TV does, is to take the
information in the transmitted signal and discard the colour portion.
Next, in order to create the colour or chrominance signal, the three separate
RGB signals are again combined in the following proportions to produce two
new intermediate signals.
I = 0.74 (R'-Y) - 0.27 (B'-Y) = 0.60 R' - 0.28 G' - 0.32 B'
Q = 0.48 (R'-Y) + 0.41 (B'-Y) = 0.21 R' - 0.52 G' + 0.31 B'
The I and Q signals are bandwidth limited and separately modulated onto a
carrier with frequency of 3.58 MHz and 90 degrees out of phase with
other. The resultant signals are then added together producing a quadrature
amplitude modulated (QAM) chrominance signal.
As was stated earlier, S-Video provides much better quality
as compared to a composite connection because the brightness signal (Y) which
carries clock pulses travels separately from the color signal (U, V), thus
preventing color crosstalk aberrations, along with a frequency bandwidth
of 6 MHz ensuring higher
sharpness at 500 lines.
Composite video input
Used for composite signal transmission, today, most
TV sets have at least one composite video input, characterised by the yellow
RCA plug. It is used for transmission of video along with audio (on separate
connectors coloured white and red). The bandwidth supported
is narrower than that of
S-Video being only 4.2 MHz, hence
the low sharpness. The bearer is a single wire with
shielded earth, requiring that the colour and brightness or luminance signals
be mixed. Because the two signals are mixed, they require separation at the
receiver. The separation is never perfect due to the overlap of some frequencies
from both signals when they are originally mixed producing a form of
color crosstalk aberration, something that is noticeable in contrast
Digital Video, also known as DV, IEEE 1394, FireWire and i-link. Video that
has been produced by a DV camera for example, and can be easily imported into
a computer for editing
same rate as D-1, D-5, or Digital Betacam video, although the color information
is only half the D-1 rate: 4:1:1 in 525-line (NTSC), and 4:2:0 in 625-line
(PAL) formats. DV images are compressed but use a superior technique to motion-JPEG,
allowing for higher-quality 5:1 compression. DV video data is transmitted
at a guaranteed rate (known as isochronous), which is a feature of the IEEE
1394 bus, supporting data transfer rates
of up to 400Mbps
Connect your camcorder to the XRecorder and then save your videos to your
PC through the XRecorder. Because the XRecorder performs the compression for
you (and at a very high quality), you save on both disk space