Linear Acoustic LA-5448, Руководство пользователя

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Linear Acoustic LA-5448 AC-3 Frame Synchronizer/Rate Shaper User Guide Menus
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I/O Menu
The AES input formats of the LA5124 can be set to Professional 32-Bit, Consumer (also
32-bit with the Pro/Consumer mode bit set to Consumer), 16-Bit Channel 1, and 16-Bit
channel 2. These can be independently adjusted on an input-by-input basis, and defaults
to Pro 32-Bit. Note that most all gear is set to 32-bit mode, and only in rare cases does the
pro/consumer bit matter.
The format of all of the outputs can be varied between Pro 32-Bit and Consumer. This is
a single setting for all outputs and defaults to Pro 32-Bit. We have found that the Aastra/
Harris Flexicoder requires this setting to be Consumer, but that is the only case of which
we are aware.
Delays can be independently set for each of the inputs, and are adjustable in 32 msec
(single AC-3 frame) increments up to about four seconds.
The AES output validity bit can also be set, and is defaulted to “Invalid” to indicate that
the signals present in the AES stream are not suitable for direct conversion back to analog.
As the interpretation of this bit varies by manufacturer, we have made it adjustable to
match any situation.
Silent frame mode is enabled by default and has the function of keeping a continuous
AC-3 stream flowing from each output of the LA-5448 in case of input error or loss.
If a corrupt AC-3 frame is detected, the last good frame is repeated, then silent frames
equal to the data rate and channel mode (acmod) of this last good frame are output
until valid error free AC-3 frames return. Note that if Silent Frame mode is required
and automatically enabled for Stream Shaping functionality.
Stream Shape mode is enabled by default and has the function of keeping the output
data rate fixed at 448 kbps regardless of the input data rate. No audio or metadata is
affected by this. When combined with frame synchronization and silent frame, it al-
lows AC-3 streams of the same or different rates to be switched upstream via an AES
router or other synchronous or asynchronous switch and a single-rate error-free will
be output synchronized to plant reference.
System Menu
Under this menu, the LA5124 can have all of its parameters reset to factory defaults.