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.
- Segment expression
- A segment expression addresses a part of a soundfile with a non-zero duration. It can consist of (1) a segment name, or (2) of two label expressions (see below) specifying the beginning and the end of the segment, or (3) of two label expressions (see below) specifying the position of the segment and its duration.
|labelexpression_labelexpression||(beginning and end)|
|labelexpression_+labelexpression||(beginning and duration)|
|labelexpression_-labelexpression||(end and duration)|
- 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.
|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|
label expression description value in samples comment x x samples x xs x seconds x * sr xms x milliseconds x / 1000 * sr xHz periode of a signal with x Hz sr / x xkHz periode of a signal with x kHz sr / (x * 1000) x% x percent of the signal length l * x / 100 usage 1 and 2 only x%% x per mill of the signal length l * x / 1000 usage 1 and 2 only segid begin and length of the segment with id segid usage 3 only segid:b begin of the segment with id segid usage 3 only segid:e end of the segment with id segid usage 3 only segid:l length of the segment with id segid usage 3 only with: x = a number sr = signal sampling rate in Hz l = signal length in samples (e.g. soundfile length) segid = id of a segment defined in the xml-file item
addresses 0 samples to 4 seconds
addresses 100 samples after the beginning of SegmentB for a duration of 10 seconds
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!