| High Resolution EUS Video Capture
Digital video editing has become more popular
both in the consumer and professional sectors. There are a
variety of video capture devices currently on the market making
the selection process quite a challenge. The ideal hardware
and software configuration should be easy to install, easy
to configure, have a user-friendly interface and most importantly
be free from software crashes.
Digital video refers to series of sequential
images captured and stored in a computer in the form of files
without any loss of data. The data is stored as a binary signal
and the additional noise and loss of picture and sound quality
that may accompany analog video (VHS and S-VHS) is not seen
with digital video. The process of converting the waveform
data of an analog signal to binary form is known as digitizing.
Various capture devices are used to accomplish this task.
Most EUS processors have an S-video output
(Fig 1). This is a high quality analog output. Some processors
also have RGB output (digital), which is superior to S-video.
EUS imaging is a grayscale imaging and RGB output does not
appear to significantly improve upon S-video when these images
are compared during playback. To capture analog video to digital,
a capture device is required that will convert the analog
signal to a digital signal.
Figure 1: An S-video cable is shown on the
left. The S-video output from the endoscopy processor is the
upper socket on the right.
We have used the Dazzle video Creator II
capture device. This is a stand-alone box that has inputs
for S-video and composite video (both analog inputs). Output
is via coaxial cable to its PCI (peripheral computer interconnect
bus)MPEG-2 encoder/ decoder card (hardware card that encodes
and decodes video data in an MPEG-2 format). The card is installed
into a vacant PCI slot in the PC. We have a Dell computer
with a Pentium III processor (the brains of the computer),
an 80 Gigabyte hard drive (area where data is stored)and 256
MB of RAM (random access memory). A very nice software bundle
accompanies the Dazzle capture device. The Dazzle Moviestar
software opens up with an interface that displays the image
on the right and thumbnails of the previously captured clips
on the left. Buttons for capture are easy to find and facilitate
one click initiation of capture. A convenient feature of this
software is the ability to set the default limit of capture
to a fixed duration so that if you forget to turn off the
capture while engrossed in the EUS exam, you will not end
up with a long and useless footage that needlessly takes up
your hard drive space. The default setting automatically numbers
the images serially so that one can concentrate on the exam
rather than stop and label each clip. A cordless optical mouse
removes some of the tangles due to cords and provides more
freedom for the operator in running the controls.
Video can be captured in several different
formats that are defined by the way data is stored, compressed
and decompressed. The Dazzle device allows for capture in
MPEG-1 or MPEG-2 formats. MPEG-2 images are ideal for DVD
authoring and can be played in high-resolution full screen
playback. A scaled down version of a DVD authoring software
(Sonic Solutions DVDit! LE) accompanies the package and one
can produce DVD quality movies that can be burnt to CD-R or
DVD-R disks. Details of the products that are mentioned in
this article can be found in the links listed under references.
References
www.sonic.com
www.dazzle.com
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