M-AUDIO Delta 410 - Manual (Page 32)

MASTER CLOCK: This section allows you to select the source of the board’s
master clock: Internal Xtal (crystal) or S/PDIF In. Master clock operation is
outlined in the Synchronization section of this manual. Internal Xtal is the default
setting. Be sure to select "S/PDIF In" if you will be recording or monitoring an
S/PDIF stream, or if you wish to synchronize your digital audio with a S/PDIF
source device.
NOTE: If "S/PDIF In" is selected as the master clock source, be
sure to supply a valid S/PDIF signal to the board’s active S/PDIF
input. Otherwise, erratic timing and/or improper sample rates will
be experienced.
Once a master clock source has been selected, its synchronization status is
continually monitored and displayed below the master clock radio buttons. If
internal crystal is selected, the status display will always say "Locked." On the
other hand, if S/PDIF In is selected as the master clock source, the control panel
will display "Locked" only when a valid S/PDIF signal is detected. It will display
"Unlocked" when there is no signal at the selected input, or when the signal is
corrupt or invalid for any reason.
CODEC SAMPLE RATE: This section indicates the present board sample rate,
as set by application software. The sample rate selected here will be used to drive
the digital mixer and all outputs. The "Rate Locked" checkbox is used to force a
sample rate upon the system. It is disabled by default to allow software access to
all supported sample rates. When checked, it causes the driver to only operate at
the selected sample rate. This means that any application that attempts to open
the Delta 410 driver at a sample rate other than the one selected here will fail to
do so and will post an error message. "Reset Rate When Idle" is selected when
you want the sample rate to return to a particular setting when a software
application is not actively using the board. This is particularly handy for keeping
the digital mixer running at a specific sample rate.
NOTE: Because the digital monitor mixer runs at the sample rate of
the rest of the board, and because sample rate directly affects
frequency response, it may be desirable to keep the sample rate at
or above 44.1 kHz while using the monitor mixer. This is
accomplished by enabling "Reset Rate When Idle" and selecting a
sample rate of 44.1 kHz or greater.
S/PDIF SAMPLE RATE: When using S/PDIF In as your master clock, this
section tells the driver what the expected S/PDIF input sample rate is. The section
is only displayed when the board is set to use S/PDIF In as the master clock
source. From the list, select the sample rate closest to that of the S/PDIF input
data. The sample rate selected here will be the only sample rate available to the
software applications. Therefore, you must set your audio software application to
this same sample rate or else the application will display an error message.
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