About the Vamp Test Plugin¶

The Vamp Test Plugin is a plugin that does no real work, does not analyse its input at all, and always returns the same results. (With one caveat: you should feed it at least 15 seconds of input audio, because it returns features across a 15-second span.)

It has several outputs, which are designed to test the host's handling of various aspects of the Vamp OutputDescriptor SampleType and SampleRate settings. Note that all output features have labels indicating the expected timing and (in some cases) values for the feature.

Think of it as the Vamp plugin equivalent of a TV test pattern or printer test page.

Outputs¶

The plugin outputs are listed below, with a description and an example of Sonic Annotator's display of the output features. The output comes from the forthcoming Sonic Annotator v0.7.1 -- use of this plugin turned up a bug in 0.7 which 0.7.1 fixes!

instants¶

The instants output is a VariableSampleRate output containing ten instants explicitly timestamped at 1.5 second intervals. They are labelled by number and time.

"test.wav",0.000000000,"1 of 10 at 0" 
,1.500000000,"2 of 10 at 1.5" 
,3.000000000,"3 of 10 at 3" 
,4.500000000,"4 of 10 at 4.5" 
,6.000000000,"5 of 10 at 6" 
,7.500000000,"6 of 10 at 7.5" 
,9.000000000,"7 of 10 at 9" 
,10.500000000,"8 of 10 at 10.5" 
,12.000000000,"9 of 10 at 12" 
,13.500000000,"10 of 10 at 13.5" 

curve-oss¶

The curve-oss output is a OneSamplePerStep output containing 20 values from 0 to 0.95 in increments of 0.05. They have implicit timing, so their timestamps will depend on the process block size. The expected times are calculated by the plugin and returned in the feature labels.

"test.wav",0.000000000,0,"1 of 20: 0 at 0" 
,0.023219954,0.05,"2 of 20: 0.05 at 0.023" 
,0.046439909,0.1,"3 of 20: 0.1 at 0.046" 
,0.069659863,0.15,"4 of 20: 0.15 at 0.069" 
,0.092879818,0.2,"5 of 20: 0.2 at 0.092" 
,0.116099773,0.25,"6 of 20: 0.25 at 0.116" 
,0.139319727,0.3,"7 of 20: 0.3 at 0.139" 
,0.162539682,0.35,"8 of 20: 0.35 at 0.162" 
,0.185759637,0.4,"9 of 20: 0.4 at 0.185" 
,0.208979591,0.45,"10 of 20: 0.45 at 0.208" 
,0.232199546,0.5,"11 of 20: 0.5 at 0.232" 
,0.255419501,0.55,"12 of 20: 0.55 at 0.255" 
,0.278639455,0.6,"13 of 20: 0.6 at 0.278" 
,0.301859410,0.65,"14 of 20: 0.65 at 0.301" 
,0.325079365,0.7,"15 of 20: 0.7 at 0.325" 
,0.348299319,0.75,"16 of 20: 0.75 at 0.348" 
,0.371519274,0.8,"17 of 20: 0.8 at 0.371" 
,0.394739229,0.85,"18 of 20: 0.85 at 0.394" 
,0.417959183,0.9,"19 of 20: 0.9 at 0.417" 
,0.441179138,0.95,"20 of 20: 0.95 at 0.441" 

curve-fsr¶

The curve-fsr output is a FixedSampleRate output which contains 10 implicitly timed features with values from 0 to 0.9 in increments of 0.1.

This output has a SampleRate of 2.5, so the features should appear at 0.4 second intervals.

"test.wav",0.000000000,0,"1 of 10: 0 at 0" 
,0.400000000,0.1,"2 of 10: 0.1 at 0.4" 
,0.800000000,0.2,"3 of 10: 0.2 at 0.8" 
,1.200000000,0.3,"4 of 10: 0.3 at 1.2" 
,1.600000000,0.4,"5 of 10: 0.4 at 1.6" 
,2.000000000,0.5,"6 of 10: 0.5 at 2" 
,2.400000000,0.6,"7 of 10: 0.6 at 2.4" 
,2.800000000,0.7,"8 of 10: 0.7 at 2.8" 
,3.200000000,0.8,"9 of 10: 0.8 at 3.2" 
,3.600000000,0.9,"10 of 10: 0.9 at 3.6" 

curve-fsr-timed¶

The curve-fsr-timed output is a FixedSampleRate output in which the features have explicit timestamps. The features have values from 0 to 0.9 in increments of 0.1. They are not, however, equally spaced.

According to the Vamp Plugin Programmers' Guide, "The host may round the timestamp according to the sample rate given in the output descriptor's sampleRate field". In my view this is the right thing for a host to do, although it's technically optional. This output tests that behaviour by providing features at timestamps that do not lie on sample boundaries, along with a label indicating what the host would be expected to snap them to (always the nearest sample boundary).

The output has a SampleRate of 2.5, so the features should be snapped to 0.4 second boundaries.

Thus:

"test.wav",0.000000000,0,"1 of 10: 0 at 0 snap to 0" 
,0.000000000,0.1,"2 of 10: 0.1 at 0 snap to 0" 
,0.000000000,0.2,"3 of 10: 0.2 at 0.166 snap to 0" 
,0.400000000,0.3,"4 of 10: 0.3 at 0.333 snap to 0.4" 
,2.000000000,0.4,"5 of 10: 0.4 at 2 snap to 2" 
,2.000000000,0.5,"6 of 10: 0.5 at 2 snap to 2" 
,2.000000000,0.6,"7 of 10: 0.6 at 2.166 snap to 2" 
,2.400000000,0.7,"8 of 10: 0.7 at 2.333 snap to 2.4" 
,4.000000000,0.8,"9 of 10: 0.8 at 4 snap to 4" 
,4.000000000,0.9,"10 of 10: 0.9 at 4 snap to 4"