jalv

jalv is the underliying host powering calvo. Each plugin is loaded on a new process and connected to previous/next plugins. This module contains process spawn methods.
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Methods

(inner) addToQueue(plugin, type, command)

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Add a command to the plugin instance queue
Parameters:
Name Type Description
plugin plugin The plugin instance.
type string Can be 'set, controls, monitors'
command string command to execute.
Returns:
null if no plugin is specified

(async, inner) getControls(plugin, type)

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Gets the control values for a jalv process.
Parameters:
Name Type Description
plugin plugin Plugin instance (from rack)
type string Type of control to get('controls'|'monitor' )
Returns:
the control value as json: ctrlName: ctrlValue

(inner) jalvStdoutToJSON(str, command)

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Formats and convert a JALV kvp stdout (CONTROL = VALUE) into a json object.
Parameters:
Name Type Description
str string JALV stoud to format
command string the command invoked which resulted in this output.
Returns:
a JSON object. key: value

(inner) kill_plugin(process, rackIndex)

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Kills the plugin process.
Parameters:
Name Type Description
process pluginProcess
rackIndex number

(async, inner) processQueue(plugin)

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See:
  • settings
On calvo, Jalv host is spawned as a child process and we take the values from stdout. To provide at least, a very basic monitoring, a queue system is necesary. The queue will 'tick' every x ms according to JALV_POLLING_RATE setting. each tick will process a command and wait for the response. Different commands have different priorities: SET = HIGH, controls = MID, monitors = LOW As monitors spams the stdout buffer it was neeeded to only call it when nothing else is needing the buffer.
Parameters:
Name Type Description
plugin plugin
Returns:
null if no Selected plugin or the process is busy (wating for a response)

(inner) setControl(plugin, control, value)

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Set a value on a control (in queue)
Parameters:
Name Type Description
plugin plugin Plugin
control string Control name. Uses `symbol` property of LV2 spec.
value number Value to assign.
Returns:
null if no plugin is specified

(async, inner) spawn_plugin(plugin, rackIndex)

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Spawns a plugin. It will execute jalv and load the plugin. ALl communcations can be reachead via the process now at plugin.process
Parameters:
Name Type Description
plugin plugin
rackIndex *
Returns:
The nodejs child process.

(inner) write(process, msg)

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Writes a message to a plugin process.
Example

JALV Commands

      help              Display help message
      controls          Print settable control values
      monitors          Print output control values
      presets           Print available presets
      preset URI        Set preset
      set INDEX VALUE   Set control value by port index
      set SYMBOL VALUE  Set control value by symbol
      SYMBOL = VALUE    Set control value by symbol
Parameters:
Name Type Description
process jalvProcess The jalv process to write into. (plugin.process)
msg string The Jalv prompt supports several commands for interactive control.

(async, inner) writeWait(process, command, maxRetriesopt, retriesWaitopt)

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Write to a process stdin and wait for a response on stdout. While waiting, it will set the process.busy flag, so the queue will not advance until this function is finished. *
Parameters:
Name Type Attributes Default Description
process pluginJalvProcess The plugin instance JALV process.
command string The command to execute on JALV
maxRetries number <optional>
 10 How many time retry before giving up.
retriesWait number <optional>
 5 How many ms to wait before each retry.
Returns:
A JSON file with the (parsed) output for the given command.