360 Systems Instant Replay DR-554 - Manual (Page 10)

Page 10 Instant Replay Owner's Manual
external drive can be used as a backup device, or to move cuts from one unit to another. Also,
material intended for a specific purpose can be removed from the unit to prevent unauthorized use.
The Copy features allow a single Cut, a Bank, or all Cuts on a Disk to be copied from one drive to
another. Although we recommend using the internal hard drive for all critical recording and
playback, the external drive can be used in the same way as the internal drive, except that the external
drive cannot be used to make linear recordings. See “Using an External Drive” on page 32.
All menus, displays and functions relating to use of the External Drive are enabled by setting the
External Drive item in the Configuration Menu to ENABLED.
Recording Formats and Sample Rate Conversion
The standard Model DR-554-E stores a total of twenty-four hours of stereo audio. Instant Replay
normally uses Dolby® AC-2 ™ coding, which provides extended storage time while maintaining
superb audio quality. Instant Replay 2.0 can also record in uncompressed linear format at 48K or
44.1K sample rates. Refer to the chart on page 11 for the recording times available for each model in
the linear formats.
An individual Cut can be as short or long as you like, limited by the total unused time remaining on
the hard disk. The time remaining can be found by holding down the STOP button. The display will
read (Hours:Minutes:Seconds):
TIME LEFT HH:MM:SS
## CUTS HH:MM:SS
The Time Left Indication reflects the choice of Recording Format, so the displayed value will be
accurate whether Dolby® AC-2 or a linear format is chosen. Under some conditions, the display
may indicate MAX LENGTH rather than TIME LEFT. This is normal for hard drives larger than 2
gig when they have a relatively small amount of space used. This can also happen with any size drive
after the unit has been used for some time, and many Cuts have been recorded and erased. See
“Maintenance and Disk Operations” on page 49.
There are three recording formats available. The standard format used is 48K AC-2. This uses the
Dolby® AC-2 encoding system to allow five times the audio storage of 48K Linear format recording.
The AC-2 system is of very high quality and is recommended for all but a few applications:
When the Instant Replay will be required to provide a digital output at 44.1 K. (Format and Sample
Rate are determined at the time of recording and cannot be changed.)
When the audio being reproduced may be subjected to other forms of data compression as part of the
transmission path, for example a satellite link or telephone codec.
In applications where the exact same digital data must be reproduced. An example of this is when
using digital audio test signals to test the digital I/O or other performance factors.
AC-2 has been successfully used in applications with recorded SMPTE Time Code paired with mono
audio. This has been applied to the synchronization of lighting and show controllers with Instant
Replay.
WARNING
Note that while you can have Cuts recorded in any of the three formats stored in the unit, it is best not
to mix formats on a particular project. Switching from a 48K Linear or 48K AC-2 to 44.1 will cause
the output sample rate to change, causing possible disturbance of equipment monitoring the digital
outputs. (The analog and headphone outputs will not be affected.)