Output Sample Type and Sample Rate¶

A Vamp plugin takes audio as input, as a series of process blocks with associated timestamps, and returns a series of "feature" structures. The plugin may return any number of features from each process call, and any number of features from getRemainingFeatures once all audio has been received.

Features are associated with a particular output of the plugin. The plugin declares that each output has certain properties, which constrain the sort of feature data the host can expect to see. (See diagram.)

A feature may or may not have a timestamp. Whether a timestamp is provided -- and, if it is provided, what it means -- are determined by the SampleType and SampleRate properties of the plugin output on which the feature is returned.

SampleType¶

A plugin output's SampleType property may be either OneSamplePerStep, FixedSampleRate, or VariableSampleRate. Here's what they mean.

OneSamplePerStep¶

This is the simplest option. If an output is declared as having a SampleType of OneSamplePerStep, then any features returned from