M-Audio Delta DiO 2496 Manual page 13

CODEC SAMPLE RATE: This section is enabled only when the board is set to use
the internal crystal (Internal Xtal) as the source of its master clock. It is disabled
(greyed-out) when the master clock is set to S/PDIF In. 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 DiO driver at a sample rate other than the one select-
ed here will fail to do so. "Reset Rate When Idle" is selected when you want the
sample rate to return to a particular setting when a software application is not active-
ly using the board. This is particularly handy for keeping the digital mixer running
at a specific 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: This section is enabled only when the board is set to use
S/PDIF In as the source of its master clock. It is disabled (greyed-out) when the
master clock is set to internal crystal. When S/PDIF In is used as the master clock,
the software applications need to be manually informed of the S/PDIF Input sample
rate. You should select the sample rate closest to that of the S/PDIF source. While
'S/PDIF In' is the master clock source, and you have a sample rate selected here, the
software application(s) using the Delta DiO will be prevented from selecting any
other sample rate.
NOTE: When S/PDIF In is the master clock source, the digital mon-
itor mixer will run at the sample rate received at the S/PDIF In.
This may or may not adversely affect the frequency response of
the digital mixer.
MULTITRACK DRIVER DEVICES: The Delta DiO drivers are intelligent enough
to synchronize the beginning of recording and playback across all audio devices on
the board. When using application software that is capable of using multiple chan-
nels simultaneously, select "Single and In-Sync" to ensure that all four output chan-
nels will begin playback at the same time. Otherwise select "Independent" to allow
the output channels to play independently. This may be desirable if more than one
application needs to access different DiO channels at the same time.
DMA BUFFER SIZES: This section allows you to specify the amount of system
memory dedicated to buffering digital audio. Setting a buffer size that is too small
may result in clicks or pops in the audio stream as some data may be lost. Larger
buffers cause slightly more latency but prevent the pops and clicks that might occur
with smaller buffer sizes – the default settings are recommended but you may desire
to tweak these default settings to suit your tastes.
13