M-AUDIO Delta 410 - Manual (Page 13)

The Digital Monitor Mixer
The Delta 410 PCI Audio Card has a hardware digital audio mixer built into its
PCI controller chip. It accepts digital audio streams from all hardware inputs and
all outgoing software audio devices, mixes them with 36-bit internal precision
and then provides the mixed output to one or more locations. For the purpose of
monitoring, the output of the mixer may be routed, via the control panel’s
Patchbay/Router page, to the first set of Delta 410 analog outputs (OUT1/OUT2
as a stereo pair) and/or the S/PDIF digital output. At the same time, the mixer
may be used for stereo mix-down, with the mixer’s output recorded into the
user’s application software. The digital audio mixer is configured and controlled
by the included Delta Control Panel Software.
The Patchbay / Router
In addition to the built-in monitor mixer, the Delta 410 PCI Audio Card includes
an output patchbay/router. The patchbay/router allows each output (analog or
digital) to be connected to a variety of input sources. The 410’s outputs may
accept audio from software sources (these output devices are visible in your
audio software applications) or from hardware sources such as the analog and
digital inputs or the monitor mixer. This capability makes the Delta 410 quite
flexible for playing and monitoring any audio file format, or directly connecting
inputs to outputs for system test purposes.
Synchronization
For proper operation, the entire Delta 410 system is always synchronized to a single
master clock. The master clock is chosen via the Delta Control Panel software, or
may be set from within your ASIO or EASI application. This clock may be derived
from the Delta 410’s internal crystal oscillators or the S/PDIF In. Most of the time
the master clock is taken from the internal crystal oscillators. However, the S/PDIF
option is used in situations where the Delta 410 must be synchronized to external
digital audio or sample rates derived from an external S/PDIF device.
Using the initial default setting, the master clock is derived from the internal
crystal oscillators. Operation in this mode is similar to that of a generic sound
card – for instance, when a sound file is played through the Delta drivers, the
software application playing the sound file is responsible for setting the sample
rate in the sound card’s hardware. The Delta 410 supports these sample rates by
using either of its internal crystal oscillators and dividing the rate of that
oscillator by some value to derive the proper sample rate.
In situations where S/PDIF In is being used, the Delta 410 must be configured to
get its master clock from the S/PDIF In data stream. The reason for this is simple
– an S/PDIF data stream coming from an external source is rarely going to be in
sync with the Delta 410 (or other digital audio devices in the system for that
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