Programmer Guide/Command Reference/SEGMENT: Difference between revisions
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:Note: If the segment expression specifies a label at position ''lpos'', the return value is <code>''lpos'' ''lpos'' '''0'''</code>. | :Note: If the segment expression specifies a label at position ''lpos'', the return value is <code>''lpos'' ''lpos'' '''0'''</code>. | ||
*error: the command returns an empty string and the error- or warning-code is stored in variable <code>RC</code> | *error: the command returns an empty string and the error- or warning-code is stored in variable <code>RC</code> | ||
==See also== | |||
[[Programmer_Guide/Class_Library/BDataSet|class BDataSet]], [[../LOAD|LOAD SOUNDFILES]], [[../INT|INT]], [[../NUM|NUM]], [[Programmer_Guide/Shell_Items/File|file item (xml)]] | |||
==Description== | ==Description== | ||
The segment expression <var>segexpr</var> specifies a label (position) in a signal or a segment (part) of a signal. The command evaluates the segment expression and returns the label position or the begin, end and length of the segment. | The segment expression <var>segexpr</var> specifies a label (position) in a signal or a segment (part) of a signal. The command evaluates the segment expression and returns the label position or the begin, end and length of the segment. | ||
| Line 69: | Line 70: | ||
| ||''segid''||=||id of a segment defined in the xml-file item | | ||''segid''||=||id of a segment defined in the xml-file item | ||
|} | |} | ||
==Examples== | ==Examples== | ||
Address 0 samples to 4 seconds of the current soundfile: | Address 0 samples to 4 seconds of the current soundfile: | ||
Revision as of 11:39, 27 April 2011
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 variableRCis set to 0.
- Note: If the segment expression specifies a label at position lpos, the return value is
lpos lpos 0.
- error: the command returns an empty string and the error- or warning-code is stored in variable
RC
See also
class BDataSet, LOAD SOUNDFILES, INT, NUM, file item (xml)
Description
The segment expression segexpr specifies a label (position) in a signal or a segment (part) of a signal. The command evaluates the segment expression and returns the label position or the begin, end and length of the segment.
segexpr description bexpra position (label) at bexpr bexpr_eexpra segment with begin bexpr and end expr bexpr_+lexpra segment with begin bexpr and length lexpr (end = bexpr+lexpr) eexpr_-lexpra 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 * 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
Examples
Address 0 samples to 4 seconds of the current soundfile:
segment 0_4s
Address 2 seconds in the middle of the current soundfile:
segment 50%-1s_+2s
Address 1 second to 1 second plus 100 samples of a signal with 10kHz sampling rate a 5 seconds duration:
segment 1s_+100 10000 5*10000
Note:XML attributes and element names and segment id's are case sensitive!
Address the whole signal of segment seg1:
segment seg1 xmlfile SR ASeg ID P L
Address the signal from the beginning of seg1 to the end of seg1 plus 2 seconds:
segment seg1:b_seg2:e+2s xmlfile SR ASeg ID P L
