Dragonfly is a speech recognition framework. It is a Python package which offers a high-level object model and allows its users to easily write scripts, macros, and programs which use speech recognition.

It currently supports the following speech recognition engines:

  • Dragon NaturallySpeaking (DNS), a product of Nuance
  • Windows Speech Recognition (WSR), included with Microsoft Windows Vista, Windows 7, and freely available for Windows XP

Dragonfly’s documentation is available online at Read the Docs. Dragonfly’s FAQ is available at Stackoverflow. Dragonfly’s mailing list/discussion group is available at Google Groups.

Usage example

A very simple example of Dragonfly usage is to create a static voice command with a callback that will be called when the command is spoken. This is done as follows:

from dragonfly.all import Grammar, CompoundRule

# Voice command rule combining spoken form and recognition processing.
class ExampleRule(CompoundRule):
    spec = "do something computer"                  # Spoken form of command.
    def _process_recognition(self, node, extras):   # Callback when command is spoken.
        print "Voice command spoken."

# Create a grammar which contains and loads the command rule.
grammar = Grammar("example grammar")                # Create a grammar to contain the command rule.
grammar.add_rule(ExampleRule())                     # Add the command rule to the grammar.
grammar.load()                                      # Load the grammar.

The example above is very basic and doesn’t show any of Dragonfly’s exciting features, such as dynamic speech elements. To learn more about these, please take a look at the project’s documentation here.

Rationale behind Dragonfly

Dragonfly offers a powerful and unified interface to developers who want to use speech recognition in their software. It is used for both speech-enabling applications and for automating computer activities.

In the field of scripting and automation, there are other alternatives available that add speech-commands to increase efficiency. Dragonfly differs from them in that it is a powerful development platform. The open source alternatives currently available for use with DNS are compared to Dragonfly as follows:

  • Vocola uses its own easy-to-use scripting language, whereas Dragonfly uses Python and gives the macro-writer all the power available.
  • Unimacro offers a set of macros for common activities, whereas Dragonfly is a platform on which macro-writers can easily build new commands.

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