Oracle Video server, Manual

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What Is a Digital Video Server?
1-4 Introducing Oracle Video Server
Video-on-demand and scheduled video are possible because the digital data itself
is stored as a series of stripes, typically of 32k or 64k each, with the stripes
distributed over multiple disks. Depending on the encoded bit rate, a single stripe
on a disk might represent several seconds of video time. As soon as the information
in the stripe has been sent to one client machine, the stripe can be sent to another,
so many different parts of the file can be read simultaneously, and a single copy of
a video can serve many users concurrently.
Striping also enables a sophisticated backup-and-recovery system known as RAID
(Redundant Arrays of Inexpensive Disks) Protection . With RAID, video can still
be delivered in the event of a disk failure. RAID only needs to recover a single
stripe, rather than an entire video, so the server doesn’t need to duplicate storage
space for each video, and that means that more space can be devoted to the videos
themselves.
You can learn more about striping and RAID in Chapter 2 .
What Is a Digital Video Server?
Digital-video files can be very large. A 2-hour video in an uncompressed format
may require several hundred gigabytes of storage space. So before files are stored,
they are compressed. The compressed file size depends on the codec (compression/
decompression software) and the compression rate you choose, however the same
video encoded in the
MPEG (Motion Pictures Experts Group) format at 1.5 Mbps
still requires about 2 gigabytes.
Because the amount of digital information is so large, digital video generally
demands large storage and delivery capacity. Several movie titles or customer
presentations will require multiple gigabytes of storage. For this reason, it’s not
practical to store these videos in the same places they’ll be viewed, such as:
■
desktop computers or laptop computers connected to a network
■
NC (network computing) devices that rely on a network connection and do not
include their own storage space, or
■
traditional television sets with a set-top box to enable viewing of digital video
This is where a video server comes in. A server machine is designed to offer the
storage and throughput capacities needed for timely and reliable delivery of digital
video. In turn, this means that you need not find storage for every video you want
to view on your desktop computer --- which would leave little room for anything
else!