Building Your Encoding Hardware - A Practical Guide to Video and Audio Compression - page 468

for low-budget studios. The DSR 11 is very cheap. The DR 1000 is interesting because
it has an 8-hour hard disk store fitted into it instead of a tape drive.
Having said that, DV handycam devices are not particularly good at analog-to-digi-
tal conversion, although they are very good as acquisition devices for direct shooting.
They offer a very good price-performance combination.

29.15 Cabling Your Studio

The cabling in studios and also in pro-consumer setups has for a long time standardized
on 75-Ohm coax (coaxial cable). This is used for analog composite video and also for the
serial digital signals that professional studios deploy.
Avoid the use of radiofrequency (RF) connections. RF is only designed for connect-
ing a VCR to a TV set for playing back VHS tapes. It is a truly awful way to connect any-
thing else if you are trying to do transfers. The results will always be totally unsatisfactory
and not worth compressing.
Use SCART or S-VHS if you are connecting analog. RCA phono jack connectors
are okay but you will be using composite video. The SCART and S-VHS systems deliver
the video at a better quality. Ideally, you should get the video into a digital format as soon
as possible with the minimum of generational copying or conversion.

Label the power plugs on the distribution board or you will unplug a power
supply from an online hard disk instead of the laptop when you are rushing
out to a meeting. This does bad things to the disk, not to mention that it stops
your 3-day-long compression job dead!

29.15.1 Routing Video and Audio

Trying to route video around a small studio is fairly easy. It is easy to disconnect cables
from one place and reconnect them somewhere else, which is fine for just a few comput-
ers and video decks. However, in a production environment or in a major broadcast stu-
dio it is physically impossible to create circuits by hand patching with cables.
Instead of cabling, an electronic switching system called a router is used. This is some-
times referred to as a matrix because it is a grid of inputs and outputs arranged so that the
crossing points are joined to make a connection. This allows any output to be connected to
any one of the inputs. Any of the inputs can be simultaneously connected to more than one
output. Everything is synchronized so that the switching happens during the blanking time
and the new source is then available on the next frame. So it is a combination of a switcher
and a distribution amplifier.
Common sizes for these are 8 32. If you are prepared to spend

big money, then 64, 128, 144, and 256 square units are readily available. If you need to go
bigger than this, then gang them up in multiples.
Blackmagic Design has introduced a workgroup routing solution that is economical
and may do just what you need: the Workgroup Videohub (see Figure 29-8).

× 8, 16 × 16, and 32 ×