VBrick Systems VOD-W Server VBrick v4.2.3 - Manual (Page 48)

40 © 2008 VBrick Systems, Inc.
W server and may take place even while the VOD-W is serving up a large number of
simultaneous video streams. Depending on the size of the video asset and overall VOD-W
server load, the ingestion process may only take a few minutes or more than an hour. Once
the Portal Server driven ingestion is complete, the original source video file held in the VOD-
W disk staging area is deleted.
For MPEG-1 or MPEG-2 content, a total of 6 supplemental trick files are generated in
addition to the main or original video asset. During normal playback, the actual file streamed
by the VOD server is the main MPEG asset. However, when the remote client hits the Fast
Forward (or Rewind) button on his player or Set Top Box, the VOD server gets the FF
command and uses the accompanying Fast Forward index, map, and main files to locate the
proper position in the video and begin a Fast Forward stream. Rewind works in a similar
fashion. Without these supplement trick files, viewers would be limited to basic play, pause,
and stop commands.
Ingested video content on the VOD-W is stored in the
d:\content
directory on the server.
When additional external storage is added to the VOD-W, the content resides here as well
under directory names such as
G:\content2
,
H:\content3
,
I:\content4
, or
J:\content5
. Note
that some additional storage overhead is incurred as a result of the file ingestion process. The
following table shows the total number of stored files and added overhead for each type of
MPEG video asset.
Content Backup and Recovery
The ingestion process has implications related to content backup and recovery that system
administrators need to keep in mind. VBrick strongly recommends that all stored VOD-W
video content be backed up to an external storage system, a Storage Area Network (SAN), or
a tape backup system. Backing up the ingested video content onto an external system is
insurance against the failure of one or more of the VOD-W disk drives. Since the backed up
content is stored in "post-ingested" form (the main asset plus all associated trick files),
content recovery is rapid and straightforward. The VOD-W database is backed up each
evening, so that recovery from disk failure is a relatively straightforward process of restoring
the backup file.
If a system administrator does not have a disk backup system in place, the video content
restoration is a more time consuming and labor intensive process. Each piece of video
content must be re-ingested from its original source file. If a customer has loaded several
hundred hours of video content on their VOD-W system over the course of a year, then this
manual recovery process could take many hours or even days to complete. As described
above, it is possible to replicate the original piece of MPEG-1 or MPEG-2 video content
from the stored Main Asset, although locating and copying the proper file can be time
consuming if more than a few files are involved.
MPEG Type Total Files Disk Storage Overhead
MPEG-1 6 41%
MPEG-2 6 42%
MPEG-4 6 122%