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The most straightforward use of the API allows MATLAB to interact with the Audio Weaver Designer GUI. This is documented in Interacting with Audio Weaver Designer and is sufficient for most users. More advanced scripting features are described in later sections.
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The arguments to the connect command are the source and destination modules, respectively. The subsystem itself is specified by the empty string. Thus, the first statement connects the subsystem’s input pin to the input of the ‘toFloat’ type conversion module. Similarly, the last statement connects the output of the ‘toFract” module to the output of the subsystem. In this example, the subsystem and modules only have one pin each on the input and output, so it is clear as to what connections are specified. For modules and subsystems with multiple input or output pins, we use a slightly different syntax described in Making Connections.
We can also reduce the 4 connect commands to a single command:
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Notes:
A related but more complicated example, bass_tone_control_module.m, is also provided with Audio Weaver. This other version supports both floating-point and fract32 signals.
The bass tone control presented here is only to illustrate certain Audio Weaver concepts. If you need a bass tone control in your system, see the example in Bass and Treble Tone Controls.
The design equations are written in MATLAB and allow you to control the module using MATLAB scripts. However, since the control code does not exist on the target, you will be unable to draw an inspector. To take it one step further and write the control code in C requires writing a custom audio module. This is beyond the scope of this User's Guide but points you towards the benefits of writing custom audio modules.
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This section goes into further detail regarding key concepts in Audio Weaver. These were touched upon in the tutorial in Interacting with Audio Weaver Designer and The Basics of the MATLAB API, and are given full coverage here. The concepts explain how Audio Weaver operates behind the scenes and clarifies the relationship between pins, wires, modules, and subsystems.
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Pins are added to a module by the add_pin.m function. Each pin has an associated Pin Type as described in Pins. After creating the Pin Type, call the function
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where the 2nd and subsequent arguments are passed to the awe_variable.m function. See @awe_module for a description of these parameters.
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The call to create a new empty subsystem is similar to the call to create a new module described in @awe_module
SYS=awe_subsystem(CLASSNAME, DESCRIPTION);
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The module names "sine1" and "mult" are obvious because they were specified when the modules were created. The pins names may not be obvious since they appear within the module's constructor function. To determine the names of a module's pins, you can either utilize the detailed help function awe_help described in Online Help (recommended)
awe_help multiplexor_smoothed_module
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The top-level system is still an @awe_subsystem object but it is treated differently by the build process. The main difference is how the output pin properties are handled. In a top-level system, the output pins properties are explicitly specified and not derived from pin propagation. As an added check, the pin propagation algorithm verifies that the wires attached to a top-level system's output pins match the properties of each output pin of the target. The top-level system functions are described in more detail in target_system.m and matlab_target_system.m.
In contrast, internal subsystems are created by calls to
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| Code Block |
|---|
filter = Biquad // 2nd order IIR filter
b0: 1 // First numerator coefficient
b1: 0 // Second numerator coefficient
b2: 0 // Third numerator coefficient
a1: 0 // Second denominator coefficient
a2: 0 // Third denominator coefficient
state: 0
0] |
See AWE_INFO for a description of all user settable fields in the AWE_INFO structure.
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The function new_pin_type.m was introduced in Adding I/O Pins and returns a data structure representing a pin. The internal structure of a pin can be seen by examining the pin data structure. At the MATLAB command prompt type:
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Consider the bass tone control subsystem introduced in Bass Tone Control Module. The subsystem was connected to stereo input and output pins and thus all of the internal wires hold two channels of information. If the bass tone control were connected to a mono input, then all of the internal wires would be mono and the module would operate as expected. This generality allows you to design algorithms which operate on an arbitrary number of channels with little added complexity.
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The most common time that users stumble with this concept is when they use the awe_setstatus.m command described in awe_getstatus.m and awe_setstatus.m. When you are changing the status of a module within a subsystem you must reassign the output argument as in:
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In addition to logging text script files, the Audio Weaver diary can also create compiled script files. Refer to Creating and Compiling Files.
awe_getini.m and awe_setini.m
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This global variable was first introduced in @awe_module and controls some aspects of Audio Weaver. AWE_INFO is a structure with the following fields:
AWE_INFO.displayControl – determines whether hidden variables are displayed in module and subsystem structures. Refer to @awe_module.
AWE_INFO.testControl – Used internally by DSP Concepts for automated regression tests.
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.profileMemory – specifies if memory heap information is monitored during the build process. Refer to build.m.
.echoCommands – specifies if all of the Server commands and responses are echoed to the MATLAB output window. This is primarily used when debugging and you want to monitor the communication between MATLAB and the audio Server.
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Adds a single variable to a module's inspector. This command is described in Creating User Interfaces.
add_module.m
SYS=add_module(SYS, MOD)
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Examples of how to use this function are provided in Adding Modules. Note that the set of input pin names must be unique, as well as the set of output pin names. The add_pin function checks for this and reports the following error if this condition is violated:
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By default, ISFEEDBACK=0 and a standard feedforward connection is made. Set ISFEEDBACK=1 to indicate feedback. See Feedback for a detailed discussion of using feedback within Audio Weaver systems.
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Point-to-point connections in Audio Weaver are specified via the connect.m function described in connect.m The connect.m command has an optional fourth argument which is used to indicate feedback.
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An audio module can be in one of four run-time states: Active, Muted, Bypassed, and Inactive, as described in Real-Time Tuning. The module status is set using a group of radio buttons. To add a module status control, use the syntax:
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Base and Extended Controls
We saw in the Quick Tutorial that some inspectors could toggle between showing and hiding an "extended" panel by double-clicking on the title bar. (Note that this only works for inspectors drawn by the Server; not by inspectors drawn by the Designer GUI.) Typically, the frequently used controls appear on the base panel while the less frequently used items, such as the module status, appear on the extended panel.
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The MATLAB command awe_diary.m is the primary method for creating Audio Weaver Script (.aws) files. This command is discussed in awe_diary.m and essentially captures all of the commands sent from MATLAB to the Server and logs them to a specified file. Typically, you wrap the building of a system in pairs of awe_diary commands as shown below:
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