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Land Software: LIDOS, FAUST, FAUST-iServer sind Software-Programme auf dem PC, im LAN und im Inter-/Intranet für Bibliothek, Archiv, Museum, Patente. Archivsoftware (Archivprogramm, Archivinformationssystem) ist Branchensoftware für das Faust Entry und Faust Professional, Land Software, D: Institut für. Faust ist als freie Software unter der GPL lizenziert. Am und Juli fand an der Johannes Gutenberg-Universität Mainz die erste Internationale. Land Software-Entwicklung. FAUST Professional. FAUST Standard. FAUST Entry Museum. FAUST Entry Archiv. FAUST iServer. LIDOS. FAUST iServer 9 Service - Rechner. Besuchen Sie auch unsere Homepage: afadenhaag.nl iServer. Assistent. Webhosting. Kundenprojekte.
FAUST iServer 9 Service - Rechner. Besuchen Sie auch unsere Homepage: afadenhaag.nl iServer. Assistent. Webhosting. Kundenprojekte. Unter dieser Maßgabe erfolgte die Wahl von Faust als Datenbanksoftware für die im Aufbau befindliche Bilddatenbank des ethnographischen Bildarchivs. Die. tem FAUST der Firma Landsoftware,1 welches dort seit im Einsatz ist, sehr zufrieden waren und keine andere Software einführen woll- ten. Aber bis vor. Der FAUST iServer ist ein Programm, das alle FAUST Datenbanken im Internet präsentiert. Beitrag von: Doris Land Software-Entwicklung. Postfach Unter dieser Maßgabe erfolgte die Wahl von Faust als Datenbanksoftware für die im Aufbau befindliche Bilddatenbank des ethnographischen Bildarchivs. Die. tem FAUST der Firma Landsoftware,1 welches dort seit im Einsatz ist, sehr zufrieden waren und keine andere Software einführen woll- ten. Aber bis vor. Land Software-Entwicklung FAUST Professional FAUST Standard FAUST EntryMuseum FAUST EntryArchiv FAUST iserver LIDOS FAUST 7 FAUST 7.
Faust Software VideoMaking a Polyphonic Synthesizer with Frequency Modulation Synthesis in Faust - Stanford
Type [ RegistryT ]. Type [ TableManagerT ]. Type [ TopicT ]. Type [ SupervisorStrategyT ]. List [ URL ]. Optional [ CredentialsT ]. Optional [ int ].
Iterable [ Path ]. Optional [ str ]. Optional [ Callable [[ Optional [ bytes ], Sequence [ int ], Sequence [ int ]], int ]]. Set [ str ]. Set this to True if app should only start the services required to operate as an RPC client producer and simple reply consumer.
ServiceT . By default the configuration will be read only when required. Topics are named channels for example a Kafka topic , that exist on a server.
To make an ephemeral local communication channel use: channel. TopicT . By default this will create an in-memory channel used for intra-process communication, but in practice channels can be backed by any transport network or even means of inter-process communication.
ChannelT . Or it can be an async iterator that yields values. This is like timer but a one-shot task only executed at worker startup after recovery and the worker is fully ready for operation.
The function may take zero, or one argument. If the target function takes an argument, the app argument is passed:. Like task , but executes periodically until the worker is shut down.
This is an async def function to be run at the fixed times, defined by the Cron format. Like timer , but executes at fixed times instead of executing at certain intervals.
If not set value from timezone will be taken. Decorate mode. Service to be started with the app. Type [ ServiceT ]. Return True if we are in leader worker process.
GlobalTableT . Decorate async def function to be used as CLI command. Create new faust. Event object.
EventT . If not set the partition will be chosen by the partitioner. Defaults to current time. Overrides schema if one is specified.
Signature must be unary as the FutureMessage future is passed to it. The infix notation is not limited to numbers or numerical expressions.
Arbitrary expressions A and B can be used, provided that A,B has exactly two outputs. Built-in primitives that can be used in infix notation are called infix operators and are listed below.
Please note that a more detailed description of these operators is available section on primitives. Beside infix notation , it is also possible to use prefix notation.
The partial application notation is a variant of the prefix notation in which not all arguments are given.
When doing partial application with an infix operator , it is important to note that the supplied argument is not the first argument, but always the second one:.
Please note that this rule only applies to infix operators, not to other primitives or functions. If you partially apply a regular function to a single argument, it will correspond to the first parameter.
The following example demonstrates the use of partial application in the context of a gain controller:. The ' time expression is useful when designing filters, etc.
Therefore, the values of a slider are perfectly acceptable:. Thus, various fractional delay algorithms are implemented in the Faust libraries.
Faust is a lexically scoped language. The meaning of a Faust expression is determined by its context of definition its lexical environment and not by its context of use.
To keep their original meaning, Faust expressions are bounded to their lexical environment in structures called closures. The following constructions allow to explicitly create and access such environments.
Moreover they provide powerful means to reuse existing code and promote modular design. The with construction allows to specify a local environment : a private list of definition that will be used to evaluate the left hand expression.
The letrec construction is somehow similar to with , but for difference equations instead of regular definitions.
It allows us to easily express groups of mutually recursive signals, for example:. Here is a more involved example. Let say we want to define an envelope generator with an attack and a release time as a number of samples , and a gate signal.
A possible definition could be:. The environment construction allows to create an explicit environment. It is a convenient way to group together related definitions, to isolate groups of definitions and to create a name space hierarchy.
In the following example an environment construction is used to group together some constant definitions :. For example constant. The library construct allows to create an environment by reading the definitions from a file.
For example library "filters. It works like import "miscfilter. Individual definitions can be accessed as described in the previous paragraph. To avoid name conflicts when importing libraries it is recommended to prefer library to import.
So instead of :. The component construction allows us to reuse a full Faust program e. For example component "freeverb.
Please note that component "freeverb. Explicit substitution can be used to customize a component or any expression with a lexical environment by replacing some of its internal definitions, without having to modify it.
For example we can create a customized version of component "freeverb. Reference to external C functions , variables and constants can be introduced using the foreign function mechanism.
An external C function is declared by indicating its name and signature as well as the required include file.
The file maths. Foreign functions with input parameters are considered pure math functions. They are therefore considered free of side effects and called only when their parameters change that is at the rate of the fastest parameter.
Exceptions are functions with no input parameters. A typical example is the C rand function. In this case, the compiler generates code to call the function at sample rate.
The signature part float asinh float in the example presented in the previous section describes the prototype of the C function: return type, function name, and list of parameter types.
Because the name of the foreign function can possibly depend on the floating point precision in use float, double and quad , it is possible to give a different function name for each floating point precision using a signature with up to three function names.
Only numerical functions involving simple int and float parameters are allowed currently in Faust.
No vectors, tables or data structures can be passed as parameters or returned. External variables and constants can also be declared with a similar syntax.
In the same maths. Foreign constants are not supposed to vary. Therefore expressions involving only foreign constants are only computed once, during the initialization period.
Variable are considered to vary at block speed. This means that expressions depending of external variables are computed every block.
In declaring foreign functions one has also to specify the include file. It allows the Faust compiler to add the corresponding include in the generated code.
In declaring foreign functions one can possibly specify the library where the actual code is located. It allows the Faust compiler to possibly automatically link the library.
Abstractions and applications are fundamental programming constructions directly inspired by Lambda-Calculus. These constructions provide powerful ways to describe and transform block-diagrams algorithmically.
Abstractions correspond to functions definitions and allow to generalize a block-diagram by making variable some of its parts. The following expression can be written see the sections on Split Composition and Merge Composition :.
The incoming mono signal is split to feed the two input channels of the reverb, while the two output channels of the reverb are mixed together to produce the resulting mono output.
Imagine now that we are interested in transforming other stereo effects. The resulting abstraction can then be applied to transform other effects.
Applications correspond to function calls and allow to replace the variable parts of an abstraction with the specified arguments.
For example, the abstraction described in the previous section can be used to transform a stereo reverb:. Replacing the variable part with the argument is called beta-reduction in Lambda-Calculus.
Whenever the Faust compiler find an application of an abstraction it replaces the variable part with the argument. The resulting expression is as expected:.
Pattern matching rules provide an effective way to analyze and transform block-diagrams algorithmically. The first one will match a sequential expression and invert the two part.
The second one will match all remaining expressions and leave it untouched. Therefore the application:. Please note that patterns are evaluated before the pattern matching operation.
Therefore only variables that appear free in the pattern are binding variables during pattern matching. The primitive signal processing operations represent the built-in functionalities of Faust, that is the atomic operations on signals provided by the language.
All these primitives denote signal processors , in other words, functions transforming input signals into output signals.
Faust considers two types of numbers: integers and floats. Integers are implemented as bits integers, and floats are implemented either with a simple, double, or extended precision depending of the compiler options.
Floats are available in decimal or scientific notation. Like any other Faust expression, numbers are signal processors. For example the number 0.
The waveform primitive was designed to facilitate the use of rdtable read table. It allows us to specify a fixed periodic signal as a list of samples.
Note that the quality of this oscillator is very low because of the low resolution of the triangle waveform. The soundfile "label[url:path]", n simplified syntax allows to use a single file.
A soundfile has:. If more outputs than the actual number of channels in the sound file are used, the audio channels will be automatically duplicated up to the wanted number of outputs so for instance, if a stereo file is used with four output channels, the same group of two channels will be duplicated.
If the soundfile cannot be loaded for whatever reason, a default sound with one channel, a length of frames and null outputs with samples of value 0 will be used.
Note also that soundfiles are entirely loaded in memory by the architecture file, so that the read index signal can access any sample.
Architecture files are responsible to load the actual soundfile. If label is used without any url metadata, it will be considered as the soundfile pathname.
Note that a special architecture file can well decide to access and use sound resources created by another means that is, not directly loaded from a sound file.
Most Faust primitives are analogous to their C counterpart but adapted to signal processing. Be aware that the unary - only exists in a limited form.
It can be used with numbers: The cut primitive is expressed in Faust with! In the following example, the! The int primitive can be used to force the cast of a signal to int.
This primitive is useful when declaring indices to read in a table, etc. The following example will output 1 if the incoming signal is smaller than 0.
Note that the result of this operation could be multiplied to another signal to create a condition.
The following code will output 1 if the input signal is smaller or equal than 0. The following code will output 1 if the input signal is greater or equal than 0.
Most of the C math. Faust hosts various modifiers and primitives to define one sample or integer delay of arbitrary length. They are presented in this section.
It can be seen as syntactic sugar to the mem primitive. An integer delay of N samples can be expressed as N in Faust.
Note that N can be dynamic but that its range must be bounded. This can be done by using a UI primitive see example below allowing for the definition of a range such as hslider , vslider , or nentry.
Note that floating point delay is also available in Faust by the mean of various fractional delay implementations available in the Faust standard libraries.
The rdtable primitive can be used to read through a read-only pre-defined before compilation table. The table can either be implemented using a function controlled by a timer such as ba.
The idea is that the table is parsed during the initialization step and before audio computation begins. In this example, a basic and dirty triangle wave-table is defined using the waveform.
It is then used with the rdtable primitive and a phasor to implement a triangle wave oscillator. Note that the output of.
In this example, a sine table is implemented using the sin primitive and a timer ba. The timer parses the sin function during the initialization step of the Faust program.
It is then used with rdtable to implement a sine wave oscillator. It takes an audio input that can be written in the table using a record index i.
In this example, an input signal is written in the table when record is true equal to 1. The read index is constantly updated to loop through the table.
The table size is set to , which corresponds to one second if the sampling rate is KHz. Selector primitives can be used to create conditions in Faust and to implement switches to choose between several signals.
Note that selector primitives optimize the code generated by the Faust compiler by only computing the selected signal. Note that select2 could be easily implemented from scratch in Faust using Boolean primitives:.
While the behavior of this last solution is identical to the first one, the generated code will be less optimized as the sine and the sawtooth waves will both be computed all the time.
The following example allows the user to choose between a sine, a sawtooth and a triangle wave oscillator. Note that select3 could be easily implemented from scratch in Faust using Boolean primitives:.
While the behavior of this last solution is identical to the first one, the generated code will be less optimized as the sine, the sawtooth and the triangle waves will all be computed all the time.
Widgets can be discrete e. Discrete and continuous elements are signal generators. For example, a button produces a signal which is 1 when the button is pressed and 0 otherwise:.
These signals can be freely combined with other audio signals. In fact, the following code is perfectly valid and will generate sound:.
Therefore, hslider , vslider , and nentry can for example be turned into a knob, a dropdown menu, etc. This concept is further developed in the section on UI metadata.
Continuous UI elements i. In some cases, this range is used during compilation to allocate memory and will impact the generated code. For example, in the case of:.
The hgroup primitive implements a horizontal group. A group contains other UI elements that can also be groups. In the following example, the 2 UI elements controlling an oscillator are encapsulated in a group.
The vgroup primitive implements a vertical group. The vbargraph primitive implements a vertical bar-graph typically a meter displaying the level of a signal.
Note the use of the attach primitive here that forces the compilation of the vbargraph without using its output signal see section on the attach primitive.
The hbargraph primitive implements a horizontal bar-graph typically a meter displaying the level of a signal. Note the use of the attach primitive here that forces the compilation of the hbargraph without using its output signal see section on the attach primitive.
The attach primitive takes two input signals and produces one output signal which is a copy of the first input. The role of attach is to force its second input signal to be compiled with the first one.
Such vumeters can be easily coded in Faust using an envelope detector connected to a bargraph. The problem is that the signal of the envelope generators has no role in the output signals.
Using attach x,vumeter x one can tell the compiler that when x is compiled vumeter x should also be compiled. The examples in the hbargraph Primitive and the vbargraph Primitive illustrate well the use of attach.
Labels can contain variable parts. During compilation each label is processed in order to replace the variable parts by the value of the variable.
The variable part can have an optional format digit. An escape mechanism is provided. Thanks to horizontal , vertical , and tabs groups, user interfaces have a hierarchical structure analog to a hierarchical file system.
Each widget has an associated path name obtained by concatenating the labels of all its surrounding groups with its own label.
In order to give more flexibility to the design of user interfaces, it is possible to explicitly specify the absolute or relative pathname of a widget directly in its label.
Group types are defined with the following identifiers:. Hence, the example presented in the section on the hgroup primitive can be rewritten as:.
Note that path names are inherent to the use of tools gravitating around Faust such as OSC control or faust2api.
In the case of faust2api , since no user interface is actually generated, UI elements just become a way to declare parameters of a Faust object.
Despite the fact that the signal generated by user interface elements can be used in Faust with any other signals, UI elements run at a slower rate than the audio rate.
This might be a source of clicking if the value of the corresponding parameter is modified while the program is running. This behavior is also amplified by the low resolution of signals generated by UI elements as opposed to actual audio signals.
For example, changing the value of the freq or gain parameters of the following code will likely create clicks in the case of gain or abrupt jumps in the case of freq in the signal:.
This problem can be easily solved in Faust by using the si. Therefore, the previous example can be rewritten as:.
Beware that each si. UI elements provide a convenient entry point to the DSP process in the code generated by the Faust compiler e. For example, the Faust program:.
The second argument of the addHorizontalSlider method is a pointer to the variable containing the current value of the freq parameter.
The value of this pointer can be updated at any point to change the frequency of the corresponding oscillator.
Widget labels can contain metadata enclosed in square brackets. These metadata associate a key with a value and are used to provide additional information to the architecture file.
Since the format of the value associated to a key is relatively open, metadata constitute a flexible way for programmers to add features to the language.
All metadata are removed from the label by the compiler and transformed in calls to the UI::declare method. This allows the UI::AddSomething method to make full use of the available metadata.
Metadata are architecture-specific: it is up to the architecture file to decide what to do with it. While some metadata will work with most architectures e.
Some of them are presented in the following sections. Therefore, UI elements can be ordered by placing a metadata before the declaration of the name of the UI element in the label.
For example, in the following declaration:. This system can be used to order groups as well. Ordering will be carried out on elements at the same level.
Note that global user interfaces completely replacing the one defined using the standard Faust UI primitives may be declared using global metadata.
This is the case of the SmartKeyboard interface for example. In the following subsections, the standard Faust UI metadata are documented.
Other types of metadata e. The [style:knob] metadata turns any continuous UI element i. The [style:menu] metadata turns any continuous UI element i.
The [style:radio] metadata turns a hslider or a vslider into a radio-button-menu. The orientation of the menu is determined by the type of UI element i.
The [style:led] metadata turns a vbargraph or a hbargraph into a blinking LED with varying intensity. The [style:numerical] metadata turns a vbargraph or a hbargraph into a numerical zone thus the bargraph itself is no more displayed.
The [style:dB] metadata changes the unit of a vbargraph or a hbargraph to dB. This impacts its overall appearance by applying a rainbow color scheme, etc.
The [unit:xx] metadata allows us to specify the unit of a UI element. The unit will be displayed right next to the current value of the parameter in the interface.
The [scale:xx] metadata allows for the specification of a scale different than the default linear one to the parameter in the UI.
This is very convenient when implementing complex interfaces. The [hidden:xx] metadata can be used to hide a parameter in the interface.
This feature is commonly used when making apps for Android and iOS using faust2android or faust2ios. Sensors control metadata can be used to map the built-in sensors of mobile devices to some of the parameters of a Faust program.
These metadatas are compatible with the following Faust targets and no additional step is required for them to be taken into account when the corresponding app is generated:.
This allows for the implementation of complex linear and non-linear mappings that are summarized in this figure:. For example, controlling the gain of a synthesizer using the X axis of the accelerometer can be easily done simply by writing something like:.
While the Faust compiler is available in different forms e. The generated code can be wrapped into an optional architecture file allowing to directly produce a fully operational program.
The option -o allows to reroute the standard output to a file:. Note that a wide range of faust Several fine-grained initialization methods are available.
The instanceInit method calls several additional initialization methods. The instanceConstants method sets the instance constant state.
The instanceClear method resets the instance dynamic state delay lines…. The instanceResetUserInterface method resets all control value to their default state.
All of those methods can be used individually on an allocated instance to reset part of its state.
By default computation is done sample by sample in a single loop. But the compiler can also generate vector and parallel code.
Current compilers are very sensitive to the way the code is arranged. In particular, complex loops can prevent autovectorization. Instead of generating a single sample computation loop, it splits the computation into several simpler loops that communicates by vectors.
The vector code generation is activated by passing the --vectorize or -vec option to the Faust compiler. Here is the Faust code that computes the Root Mean Square of a sliding window of samples:.
The corresponding compute method generated in scalar mode is the following:. The vector code generation is built on top of the scalar code generation see previous figure.
Every time an expression needs to be compiled, the compiler checks if it requires a separate loop or not. Expressions that are shared and are complex enough are good candidates to be compiled in a separate loop, as well as recursive expressions and expressions used in delay lines.
The result is a directed graph in which each node is a computation loop see figure below. This graph is stored in the class object and a topological sort is applied to it before printing the code.
Parallel code generation is activated by passing either the --openMP or -omp option or the --scheduler or -sch option.
It implies that the -vec option as well as the parallel code generation are built on top of the vector code generation. OpenMP is a well established API that is used to explicitly define direct multi-threaded, shared memory parallelism.
It is based on a fork-join model of parallelism see figure above. Parallel regions are delimited by pragma omp parallel constructs.
At the entrance of a parallel region, a group of parallel threads is activated. The code within a parallel region is executed by each thread of the parallel group until the end of the region.
In order not to have every thread doing redundantly the exact same work, OpenMP provides specific work-sharing directives.
For example pragma omp sections allows to break the work into separate, discrete sections, each section being executed by one thread:. As said before, parallel code generation is built on top of vector code generation.
The graph of loops produced by the vector code generator is topologically sorted in order to detect the loops that can be computed in parallel.
If a given set contains only one loop, then the compiler checks to see if the loop can be parallelized no recursive dependencies or not. If it can be parallelized, it generates:.
To illustrate how Faust uses the OpenMP directives, here is a very simple example, two 1-pole filters in parallel connected to an adder:.
The corresponding compute method obtained using the -omp option looks like this:. The reason for this is that many work stealing workloads are divide-and-conquer in nature, stealing one of the oldest task implicitly also steals a potentially large sub-tree of computations that will unfold once that piece of work is stolen and run.
It contains code to deal with WSQ and thread management. The compute and computeThread methods are the following:. The combination of the awesome LLVM technology and libfaust the library version of the Faust compiler allows developers to compile and execute Faust DSP programs on the fly at full speed and without making compromises.
In this section, we demonstrate how the Faust dynamic compilation chain can be used to embed the Faust compiler technology directly in applications or plug-ins.
The Faust compiler uses an intermediate FIR representation Faust Imperative Representation , which can be translated to several output languages.
The FIR language describes the computation performed on the samples in a generic manner. It contains primitives to read and write variables and arrays, do arithmetic operations, and define the necessary control structures for and while loops, if structure, etc.
The native LLVM based compilation chain is particularly interesting: it provides direct compilation of a DSP source into executable code in memory, bypassing the external compiler requirement.
LLVM formerly Low Level Virtual Machine is a compiler infrastructure, designed for compile-time, link-time, and run-time optimization of programs written in arbitrary programming languages.
All steps take place in memory, getting rid of the classical file-based approaches. Pointers to executable functions can be retrieved from the resulting LLVM module and the code directly called with the appropriate parameters.
The Faust compiler has been packaged as an embeddable library called libfaust , published with an associated API. Note that the library keeps an internal cache of all allocated factories so that the compilation of the same DSP code — that is the same source code and the same set of normalized sorted in a canonical order compilation options — will return the same reference counted factory pointer.
When finished, delete can be used to destroy the dsp instance. After the DSP factory has been compiled, the application or the plug-in running it might need to save it and then restore it.
To get the internal factory compiled code, several functions are available:. The libfaust library is fully integrated to the Faust distribution.
This allows applications to be remotely controlled from any OSC-capable application, programming language, or hardware device. OSC support can be added to any Faust program as long as the target architecture supports it: see tables below simply by adding the [osc:on] metadata to the standard option metadata :.
This example can be compiled as a standalone Jack Qt application with OSC support simply by running the following command:.
In order to address each application individually, only one application can be listening on a single port at one time. Therefore when the default incoming port is already opened by some other application, an application will automatically try increasing port numbers until it finds an available port.
The mixer application fails to open the default incoming port because it is already opened by noise. Therefore it tries to find an available port starting from and opens it.
Please note that the two outcoming ports and are shared by all running applications. The commands oscsend and oscdump from the liblo package provide a convenient mean to experiment with OSC control and potentially debug applications with OSC support.
The first one will be used to send OSC messages to the noise application using oscsend. The second terminal will be used to monitor the messages sent by the application using oscdump.
Messages received on terminal 2 will be preceded by T Once set we can use the hello message to scan UDP ports for Faust applications.
The OSC interface of an application the set of OSC messages we can use to control it can be discovered by sending the get message to the root:.
Transmission is OFF, xmit is set to false. The destination host for sending messages is Therefore to ensure compatibility spaces are replaced by underscores and some other characters asterisk, comma, forward, question mark, open bracket, close bracket, open curly brace, close curly brace are replaced by hyphens.
Here is as an example mix4. For each input we have a mute button and a level slider:. Please, note that blank spaces are replaced by underscores and metadata are removed during this operation.
All addresses must have a common root. This is the case in our example because there is a unique horizontal group mixer containing all widgets.
If a common root is missing as in the following code:. For example, to set the noise level of the application to 0.
Now if we move the level slider we get a bunch of messages:. This feature can be typically used for automation to record and replay actions on the user interface, or to remote control from one application to another.
It can be turned OFF any time using:. Aliases are a convenient mechanism to control a Faust application from a preexisting set of OSC messages.
The first step is to configure the TouchOSC host to Then we can use oscdump after quitting the noise application in order to free port to visualize the OSC messages sent by TouchOSC.
Here is what we get:. Several osc aliases can be inserted into a single label allowing the same widget to be controlled by several OSC messages.
Using again oscdump we can visualize the messages sent by TouchOSC:. As we can see, TouchOSC sends the x, y and z accelerometers in a single message, as a triplet of values ranging approximately from We also need to define a mapping because the ranges are different:.
An additional make httpd step is therefore required when compiling and installing Faust:. Note that make httpd will fail if libmicrohttpd is not available on the system.
HTTP support can be added to any Faust program as long as the target architecture supports it: see tables below simply by adding the [http:on] metadata to the standard option metadata :.
The -httpd option embeds a small Web server into the generated application. Its purpose is to serve an HTML page implementing the interface of the app.
As we can see, the embedded Web server is running by default on TCP port It can be open from any recent browser and it produces the page presented in the figure below:.
The communication between the application and the Web browser is based on several underlying URLs. Here is part of the json returned by mix4 :.
Multiple widgets can be queried at once by using an address higher in the hierarchy. All widgets can be controlled in a similar way.
This mode can be started dynamically using the -server URL parameter. Assuming an application with HTTP support is running remotely at the given URL, the control application will fetch its JSON description, use it to dynamically build the user interface, and allow for the access of the remote parameters.
The JSON describes the name, host, and port of the application and a hierarchy of user interface items:.
It can be either "vgroup" , "hgroup" or "tgroup". Widgets are the basic items of the user interface. MIDI is also the preferable way to control Polyphonic instruments.