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tclassp_afdiff(n) 0.5 doc "tclassp - Differentiation of audio signals"


tclassp_afdiff - tclassp afdiff

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First difference of a signal. ::tclassp::afdiff is an ASSP AOPTS command and takes the following general form :

::tclassp::afdiff method ?arg arg ...?


All AOPTS subcommands are implemented.

::tclassp::afdiff cget option

Returns the current setting of the option option. option may be any option appropraite for the underlying analysis function, see OPTIONS below.

::tclassp::afdiff configure option ?value? ?option? ?value?

For each option-value pair sets option to value. If the last option is missing its corresponding value the current value is returned. option may be any option appropraite for the underlying analysis function, see OPTIONS below.

Currently not standard behaviour, will be changed

::tclassp::afdiff exec fileNameList

Computes the differences of all files whose names are given in FileNameList. FileNameList must be a proper Tcl list. Returns the number of files processed successfully

::tclassp::afdiff info

This command returns a list of information on the AOPTS command. The first three elements of the list are

  1. the name of the analysis function

  2. the major version number

  3. the minor version number

The remaining elements consist of key-value pairs listing all available options of the analysis function and the the option type. Option type is useful for the creation of graphical user interfaces and may be:

  • bool: Options with a boolean value, best represented with check boxes

  • text: Options with a more or less free value, best represented with entry fields

  • radio: Options with a short range of fixed values, best represented by radio buttons

  • combo: Options with longer ranges of fixed values, best represented by combo boxes

  • spin: Options with continuos numerical value ranges, best represented by spin boxes

tkassp makes use of these otpion types to generate GUIs more or less automatically. In some cases, option type is the empty string to indicate that the option is not to be used in a GUI in the same way as the other options, see OPTIONS for details.

::tclassp::afdiff reset

Resets all options to the default.

::tclassp::afdiff version

Returns the version of the ASSP analysis function.


The following options do not affect the resulting analysis. They do not have an option type as defined for the AOPTSname info command. These options are available for all analysis commands.

-extension outputExtension

Defines the value of the output extension when the analysis result is written to file. Defaults to the input extension prepended with 'd' (e.g. ".wav" -> ".dwav").

-outDir outputDirectory

Defines the directory in which the resulting file (if any) is stored. Defaults to the working directory (pwd).

-counter counterVariable

If counterVariable is a fully qualified variable name, it is incremented each time the AOPTSname exec command finishes processing a file. This is useful to track the progress of the analysis especially for long file lists. If counterVariable is empty (the default) no counting is performed.

-stop stopVariable

If stopVariable is a fully qualified variable name, it is read each time the AOPTSname exec command start processing a file. Setting stopVariable to true will cause the abortion of the running AOPTSname exec command. This is useful if the necessity to abort time-consuming processes of of long file lists should arise. If stopVariable is the empty string (the default) aborting processes is not possible.

The following options will affect the results of the anaysis functions. Some are available in all ASSP analysis functions but not in all of them:

-back doBackward

Boolean specifying whether to calculate a backward difference (s'[n] = s[n] - s[n-1]). The default is to calculate a forward difference (s'[n] = s[n+1] - s[n]).

-central doCentral

Boolean specifying whether to compute a central/interpolated/3-point difference. Defaults to no (i.e. 2-point difference).


This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category tclassp of the ASSP Library Tracker. Please also report any ideas for enhancements you may have for either package and/or documentation.

See Also