SEGMENT
- Usage
1. Evaluate the segment expression segexpr, using the sampling rate and the length of the current soundfile (see LOAD SOUNDFILE).
SEGMENT segexpr [/S | /?]
- segexpr
- the segment expression to be evaluated
/S
,/?
- silent error handling; generate warnings rather than errors.
2. Evaluate the segment expression segexpr, using the specified sampling rate and length.
SEGMENT segexpr sr l [/S | /?]
- sr
- sampling rate in Hz
- l
- maximum signal duration in samples
3. Evaluate the segment expression segexpr, using the sampling rate and the segment definitions stored in the xml-file item xitem.
SEGMENT segexpr xmlfile srattr segtag idattr pattr lattr [/S | /?]
- xmlfile
- a xml-file item containing the metadata; the selected element must contain soundfile metadata and the segment definitions must be stored as child elements
- srattr
- the xml attribute of the selected element containing the sampling rate (in Hz)
- segtag
- the xml element tag used for segment definitions
- idattr, pattr, lattr
- the xml attributes used in the segment definition elements to specifiy the segment id (idattr) and its starting position (pattr) and length (lattr)
- Result
-
- success:
bseg eseg lseg
- the return value is the begin (bseg), end (eseg) and length (lseg) of the segment specified by the segment expression. The variableRC
is set to 0. - error: the command returns the empty string and the error- or warning-code is stored in variable
RC
- success:
- Description
- The segment expression segexpr specifies a position in a signal or the begin and end of a part of a signal.
segexpr description bexpr
a position (label) at bexpr bexpr_eexpr
a segment with begin bexpr and end expr bexpr_+lexpr
a segment with begin bexpr and length lexpr (end = bexpr+lexpr) eexpr_-lexpr
a segment with end eexpr and length lexpr (begin = eexpr-lexpr)
- Each part (bexpr, eexpr and lexpr) of the segment expression specifies a time in samples and may consist of one or more time values which are joined with the operator + (add) or - (subtract).
value description value in samples comment x x samples x xs x seconds x * sampling-rate xms x milliseconds x / 1000 * sampling-rate xHz periode of a signal with x Hz sampling-rate / x xkHz periode of a signal with x kHz sampling-rate / (x * 1000)
Segment Expressions
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.
Labels
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 |
Segments
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) |
Examples
0_4s
addresses 0 samples to 4 seconds
SegmentA:B+100_+10s
addresses 100 samples after the beginning of SegmentB for a duration of 10 seconds
SegmentB
addresses SegmentB
SegmentA:B_SegmentB:E
addresses the beginning of SegmentA to the end of SegmentB
SegmentB:E_-100ms
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!
- See also