Descriptors are a special kind of ProcessingData that describe numerical
attributes computed from the data in a related Processing Data object.
This computation is accomplished using 'basic' statistical computations
such as mean or nth order moments. For computing these statistics
efficiently, CLAM offers a statistical computation module that uses
functor objects with memory and template metaprogramming techniques.
Descriptor classes are storage classes where the values of these descriptors
are kept. They make extensive use of the XML storage facilities in
CLAM as a basic functionality of descriptors is storing them in an
appropriate way for later using information retrieval techniques.
Furthermore every descriptor class has an associated extractor
where the actual value computations are implemented as combination
of basic statistics.
CLAM offers low-level Descriptors and associated extractors for Audio,
Spectrum, Spectral Peaks, Frame and Segment. This latter processing
data has special descriptors as it includes temporal statistics such
as mean and deviation for other descriptors computed on a frame base.
This is a list of the low-level descriptors currently implemented
in the framework:
Apart from these low-level descriptors the same infrastructure is
used for higher-level descriptors such as melodic or rhythmic description.
- Audio Descriptors: Mean, Variance, Temporal Centroid, Attack,
Decay, Sustain, Release, Log, Attack Time, Energy, Zero Crossing Rate,
Rise Time, Decrease.
- Spectral Descriptors: Mean, Energy, Centroid, Second to Sixth
Order Moments, Irregularity, Tilt, Flatness, Kurtosis, Strong Peak,
High Frequency Coefficient, Mel Cepstrum Coefficients, Mel Cepstrum
Coefficients Derivative, Band Energy, Maximum Magnitude Frequency,
Low Frequency Energy Relation, Spread, Skewness, Rolloff, Slope, Pitch
- Spectral Peak Array Descriptors: Magnitude Mean, Harmonic
Centroid, Spectral Tilt, Harmonic Deviation, First to Third Tristimulus,
Odd Harmonics, Even Harmonics, Odd to Even Ratio
- Frame Descriptors: Spectrum Descriptors, Spectral Peak Descriptors,
Residual Spectrum Descriptors, Sinusoidal Spectrum Descriptors, Audio
Frame Descriptors, Sinusoidal Audio Frame Descriptors, Residual Audio
Frame Descriptors, Synthesized Audio Frame Descriptors, Morphological
- Segment Descriptors: Mean Frame Descriptors, Maximum Frame
Descriptors, Minimum Frame Descriptors, Variance Frame Descriptors,
Fundamental Frequency, Audio Descriptors.