Spectrum2ACMChroma Class Reference
[Processing, Analysis]

Transform an (amplitude) spectrum to a chroma profile. More...

#include <Spectrum2ACMChroma.h>

Inherits Marsyas::MarSystem.

Public Member Functions
void	myUpdate (MarControlPtr inSender)

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Detailed Description

Transform an (amplitude) spectrum to a chroma profile.

Author:

Matthias Varewyck

Date:

20090518

Todo:

• Check if parameters are independent on input sample rate (~= 8kHz)
  • Include check if provided (amplitude) spectrum was correctly computed
  • Include correct error handling (conform Marsyas rules)
  • Let the lowest F0 be higher than the diapason
  • Introduce a highest F0 additional to a lowest F0
  • Add "fan in combinator" to simplify actual chroma profile computation

This class implements the conversion of an (amplitude) spectrum to a chroma profile as described in "a novel chroma representation of polyphonic music based on multiple pitch tracking techniques" which was presented at the 16th ACM International Conference on Multimedia.

The method computes the set of pitches that best explains the salient frequencies present in the (amplitude) spectrum. The method results in (1) a chroma profile and (2) a chord evidence. (1) The chroma profile represents the normalized pitches after they were folded to one octave (2) The chord evidence represents the probability that a chord occurs in the examined frame. For an example, see the function "toy_with_chroma" in the mudbox.

Controls:

• mrs_natural/NrOfHarmonics [rw] : adjust the number of harmonics in F0 detection (should be >0)
• mrs_real/F0Weight [rw] : adjust the balance between F0 and its harmonics (between 0 and 1)
• mrs_real/LowestF0 [rw] : adjust the lowest F0 to be detected (between 0 and Nyquist frequency)
• mrs_real/ChordEvidence [r] : store the chord evidence of the last examined frame

Definition at line 56 of file Spectrum2ACMChroma.h.

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Member Function Documentation

void myUpdate

(

MarControlPtr

inSender

)

[virtual]

! should depend on input framesize !!

Reimplemented from MarSystem.

Definition at line 165 of file Spectrum2ACMChroma.cpp.

References MarSystem::ctrl_inObservations_, MarSystem::ctrl_inSamples_, MarSystem::ctrl_israte_, MarSystem::ctrl_onObservations_, MarSystem::ctrl_onSamples_, MarSystem::ctrl_osrate_, and MarSystem::updControl().

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The documentation for this class was generated from the following files:

• /home/marsyas/marsyas/src/marsyas/Spectrum2ACMChroma.h
• /home/marsyas/marsyas/src/marsyas/Spectrum2ACMChroma.cpp