WaveWarp 2.0 Component
      
Output Soundcards:
Output Stereo WAVE Driver
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Functional Description
Represents any Windows-compatible soundcard
with a stereo WAVE driver for use
as a stereo output device. This component has a single stereo input connector
which accepts a single stereo audio signal.
When this component is dragged onto the DrawingBoard, a
selection dialog box
opens
from which the specific physical hardware output device can be selected.
The bit-resolution of the device (e.g. 8-, 16-, 18-, 20-, or 24-bit)
and the index assignment can be adjusted via the WaveWarp Soundcard
Manager Interface (see the relevant sections of the
WaveWarp Users' Guide for more information).
The selection dialog box lists all available devices i.e. those which have not
yet been used on the current DrawingBoard or which have not been explicitly
excluded for use by WaveWarp.
In addition to listing the available soundcards
actually installed on the computer, the selection dialog box includes a
"New" template option which represents an unavailable (or non-existent)
soundcard. This place-holder device can be selected and connected up,
in preparation for eventual use on a computer with multiple soundcards
(or multichannel soundcards), even if the computer used when building the
DrawingBoard does not have multiple
soundcards (or multichannel soundcards) with a sufficient total number of
channels installed. An arbitrary number of placer-holder devices can be used.
When the DrawingBoard is loaded on a computer with the required number
of devices, the original place-holder devices will be automatically replaced by
the actual devices present, in the order determined by the I/O mapper within the
WaveWarp Soundcard Manager Interface.
A given device can only be connected up once on a DrawingBoard,
though it can appear on any number of DrawingBoards simultaneously.
Furthermore, for most soundcards,
only one driver per souncard can be accessed at a time.
For example, if a SoundBlaster-compatible soundcard is
already connected up to play a mono audio signal on the DrawingBoard, then it
is not permitted to also
connect up a stereo signal to the stereo driver of the same soundcard, etc.
This soundcard component can be connected up with any sample rate supported by the
underlying device. When WaveWarp is initialised (or after pressing
the
Scan System for all installed Drivers and Options
button located in the WaveWarp Soundcard Manager Interface window)
WaveWarp queries the sample rates supported by each device and
publishes the results
of this query under the Sample Rates
heading in the Input Soundcards category of the Component Library
(and also in the WaveWarp Soundcard Manager Interface window).
These reported sample rates are supposedly the ones available to the device.
However, owing to an incompleteness in the Windows WAVE reporting mechansim,
even if a desired sample rate
is not listed for a given device
it is worth trying anyway since some devices
seem to support more sample rates than reported by Windows.
In the worst case, the DrawingBoard will not play
until a valid sample rate is used.
When the DrawingBoard is played, the audio data going to a given soundcard
is converted from WaveWarp's internal floating-point representation
(nominally over the range -1 to +1) into the integer representation
corresponding to the bit-resolution of the device (8-, 16-, 18-, 20-, 24-bit etc).
It is at this point that digital clipping can occur, usually with undesirable
consequences. To avoid clipping, the signal levels throughout the DrawingBoard
must be adjusted such that the amplitude of the signal reaching the device is
within the range -1 to +1. This is entirely the responsibility of the user since
WaveWarp's flexible architecture offers complete freedom when manipulating
signal levels. The Audio Limiter and Audio
Normaliser components in the Dynamic Range Controllers category of the Component
Library are useful for helping to avoid clipping. The Decibel Audio LED component in
the Displays and Scopes category of the
Component Library is a useful diagnostic tool for checking if clipping has
occurred.
Note that by double-clicking on an output device icon, a volume slider window will open,
enabling control of the output volume from within WaveWarp. This is directly
linked to the corresponding Windows WAVE driver
device controller. Note that this feature is only supported by certain soundcards,
and may not function correctly
for others. In such cases, the volume must be controlled outside of WaveWarp using
the Windows audio mixer or the mixer software application which is provided
with the soundcard. Consult your soundcard documentation for more information.
Algorithm
n/a
Signal Implementations
Related components:
Example DrawingBoards illustrating usage:
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