User`s guide

Adding Clips to the SGI Media Server
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real-time partition. The real-time partition stores SGI Media Server clip content for
playout and the ingested media processed during the encoding process.
Most applications, including /usr/bsd/ftp, have no means to distinguish among
temporary filesystem characteristics. If you invoke ftp and use the get command on a
SGI Media Server to get a file from another platform, the content is stored on the data
partition, but not the real-time partition. However, if the put command is used on a
remote FTP client or a passive transfer is performed, then vtrftpd correctly writes to
the real-time partition, because vtrftpd is aware of the temporary filesystem.
During the put or passive file transfer process, vtrftpd periodically informs VST about
clip size. This implies that an MVCP CINF command applied to the clip will reveal
growth and change in the clip as the transfer progresses.
While the transfer is in progress, the clip is available for playout before the transfer
concludes. This is useful for large clip transfers over a slow network. A transfer may also
be initiated against a clip being actively recorded, thereby providing the ability to stream
to another platform, such as an editing station. Unlike the standard FTP daemon ftpd,
vtrftpd does not close the connection at the end of the file. The connection persists until
clip growth ceases.
If the available FTP transfer bandwidth is greater than the clip compression bit rate,
almost all of the clip will be available at the destination server for playout in real-time. It
is also possible to daisy-chain a number of servers to concurrently stream a recorded clip
over multiple hops.
The XFS real-time component provides a GRIO subsystem, which is a feature for
reserving and managing filesystem resources necessary to ensure predictable response
times under real-time conditions. The GRIO is necessary to avoid oversubscribing disk
bandwidth. The standard FTP daemon ftpd consumes resources without restraint,
which requires GRIO to regulate the filesystem access. Under this regulation, playout
and record channels are not affected. You can specify these contraints using the controls
in the /usr/vtr/config/vtrftpd.conf file. See the vtrftpd(1) man page for
details.
For DIF clips, vtrftpd transfers only the segment within the in and out points of the clip
(if they are set). This is useful when only a small portion of a large clip is needed. A clip
segment can be extracted by using an FTP transfer to the local host, and then dividing a
DIF clip into subclips by changing the edit points. This feature can also be disabled with
the toggle command site marks. Consequently, the marks will be ignored and the
whole clip will be transferred.