Difference between revisions of "Programmer Guide/General Descriptions/Segment Expressions"

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Revision as of 18:31, 18 November 2010

Segment Expressions

S_TOOLS-STx uses a special syntax to address a segment of a sound file. The syntax allows for the mixed use of segment names and time values in a complex expression known as a "segment expression". Segment expressions can be used in all commands and dialogs where a signal segment (or position/duration) can be specified (exceptions are described in the Command Reference). In dialogs, the supported value formats/types are always described in the control/dialog caption.


A label expression is a position in a sound file (e.g. the begin/end of a segment) or the duration of a segment. A label expression may consist of a sign (+/-) and one or more values formatted as described below and combined with the operators + (add) or – (subtract). If a label expression contains blanks, it must be quoted when used as an argument.

label expression explanation
segmentname:B start time of segment segmentname
segmentname:E end time of segment segmentname
segmentname:L duration (length) of segment segmentname
numberS time in seconds
numberMS time in milliseconds
number number of samples


A segment expression addresses a part of a soundfile with a non-zero duration. It can consist of (1) a segment name or (2) two label expressions specifying the beginning and end or (3) two label expressions specifying a position and the duration.

segment expression explanation
labelexpression_labelexpression (beginning and end)
labelexpression_+labelexpression (beginning and duration)
labelexpression_-labelexpression (end and duration)



addresses 0 samples to 4 seconds


addresses 100 samples after the beginning of SegmentB for a duration of 10 seconds


addresses SegmentB


addresses the beginning of SegmentA to the end of SegmentB


addresses 100 milliseconds before the end of SegmentB to the end of SegmentB

Notes: For some expressions, the values number% (percentage of the full duration) and number%% (thousandths of the full duration) can be used, but only if the 'full signal' is available/defined (e.g. for envelopes of sequence signals).A segmentname can only be used if a sound file or an audio-element of an XML-file is involved in the expression evaluation.Segment names are case sensitive!