MFCC

object MFCC extends ProductReader[MFCC]

A UGen for extracting mel frequency cepstral coefficients. It generates a set of MFCCs; these are obtained from a band-based frequency representation (using the Mel scale by default), and then a discrete cosine transform (DCT). The DCT is an efficient approximation for principal components analysis, so that it allows a compression, or reduction of dimensionality, of the data, in this case reducing 42 band readings to a smaller set of MFCCs. A small number of features (the coefficients) end up describing the spectrum. The MFCCs are commonly used as timbral descriptors.

The output values are somewhat normalised for the range 0.0 to 1.0, but there are no guarantees on exact conformance to this. Commonly, the first coefficient will be the highest value. The number of output channels corresponds to the number of coefficients specified. Technical note: The 0th coefficient is not generated as it consists of multiplying all bands by 1 and summing

Note that despite running at control-rate, the output remains constant for each FFT frame. E.g. with an FFT size of 1024 and 50% overlap, a new measure is generated every 512 audio frames, or (at control block size 64) every 8 control blocks.

Companion
class
trait Product
trait Mirror
trait ProductReader[MFCC]
class Object
trait Matchable
class Any

Type members

Inherited types

type MirroredElemLabels <: Tuple

The names of the product elements

The names of the product elements

Inherited from
Mirror
type MirroredLabel <: String

The name of the type

The name of the type

Inherited from
Mirror

Value members

Concrete methods

def kr(chain: GE, numCoeffs: Int): MFCC
Value Params
chain

the output (buffer) of an FFT UGen which transforms the audio input to track. For the FFT chain, with a standard hop of half FFT size, the FFT size should be 1024 at 44.1 or 48 kHz and 2048 at 88.2 or 96 kHz sampling rate.

numCoeffs

the number of coefficients, defaults to 13, maximum of 42; more efficient to use less of course! Since this number determines the number of output channels of the UGen, it has to be an Int .

def read(in: RefMapIn, key: String, arity: Int): MFCC