commodity components have transformed what can be achieved within
the server. The GPU provides huge
graphics processing power at negligible cost. Several functions within master control can potentially be collapsed
into a single appliance. This reduces
system complexity and with that, overall cost. It is possible for the server to
perform squeezebacks and picture-in-picture effects, add graphics, captions
and EAS, potentially saving a string of
1RU boxes downstream. (See Figure
3.) The channel-in-a-box adds further
functionality to the video server with
the integral playlist automation.
Freed from the capital and mainte-
nance costs of cart machines, the video
server has provided broadcasters the
ideal platform for multichannel deliv-
ery. Time-delayed channels are just an-
other output port on the server system.
It has given broadcasters the means to
build subchannels that use multiple
plays of the same programming, akin
to the near-VOD movie channels.
Many broadcasters need to process
incoming programs to create trails
as an essential part of their channel
branding and promotion. This has
led to the video server architecture
evolving into a complete playout sys-
tem to support ingest, editorial com-
pliance, promo creation and playout.
(See Figure 2.) Clips can be edited in
place on the central storage (nearline)
or downloaded to local storage in the
NLE workstation, with the finished
results copied back to the nearline
server ready for transmission.
For all the advances in disk capac-
ity, it still makes for more efficient
operations to use a low-bit-rate long-
GOP codec for the air servers, eas-
ing the network requirements for file
transfer and making for more efficient
use of storage. However, for program
Figure 2. The video server has evolved into a complete storage system to support
preparation, it is preferable to use a
master format, like AVC-I. The playout system may well run with two
codecs, so transcoding will form an
essential process in the system.
Newsroom playout is a special case,
where the schedule is a constantly
changing rundown, and each clip is
manually cued rather than running
against the clock. However, the requirements are not dissimilar from a
playout server. The source of the clips
may be an ingest server, recording
agency feeds or incoming lines. News
clips will also come from SNG feeds —
again, needing an ingest server — or
local camera memory cards.
Unlike playout, all news clips will
be edited, and edit-in-place on the
central storage array is the most common process. Finished clips can then
be transferred to the air server via instructions from the newsroom computer system (NRCS).
The video server has come a long
way from a simple replacement for the
VTR. Although in essence still a port
between the real-time SDI video and
the file domain, the server has enabled
the entire file-based ecosystem at the
heart of broadcast operations. That
adds many new facilities just not possible with tape, like browse, rough-cut
editing, read during record, and simple
copying and wide-area transfer.
The video server added broadcast
facilities to an IT platform: video reference, SDI I/O and real-time operation.
Of necessity, the device needs video
cards to add these features. However,
the video reference can be replaced
by network time protocol. Already
the output stream is carried over ASI,
not SDI, in many applications, and
IP is becoming more popular. The
vastly increased processing power and
bus speeds mean that deterministic