Toni: moved Programmer Guide/SPU Reference/FORMANTS - formant extraction to Programmer Guide/SPU Reference/FORMANTS

2011-04-20T13:33:51Z

moved Programmer Guide/SPU Reference/FORMANTS - formant extraction to Programmer Guide/SPU Reference/FORMANTS

← Older revision	Revision as of 15:33, 20 April 2011
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Admin: 1 revision: Initial import

2010-11-18T16:31:53Z

1 revision: Initial import

← Older revision	Revision as of 18:31, 18 November 2010
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193.171.195.8: initial import

2010-05-17T13:05:27Z

initial import

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====FORMANTS - formant extraction====

=====Usage:=====

<code>FORMANTS <var>F</var> <var>A</var> <var>M</var> <var>F0</var> <var>N</var> <var>B</var> <var>T</var> <var>MODE</var> <var>TABLE</var> <var>COL</var></code>

=====Inputs:=====

{|
|-
|<var>F, A</var>
|peak frequencies (Hz) and magnitudes (dB); vectors of same length
|-
|<var>M</var>
|number of peaks in current frame
|-
|<var>F0</var>
|fundamental frequency (in Hz, used for voiced/unvoiced decisions, optional)
|-
|<var>N</var>
|maximum number of formant candidates to be saved
|-
|<var>B</var>
|bandwidth (bias) for tracking (in Hz)
|-
|<var>T</var>
|minimum track duration (in frames)
|-
|<var>MODE</var>
|output mode
|-
|<var>TABLE</var>
|name of parameter table
|-
|<var>COL</var>
|first column of table to be used for formant data
|}

=====Outputs:=====

None; output values are stored in the table

=====Function:=====

This module extracts formant tracks from the input peak data. The input vectors <var>F</var> and <var>A</var> are the frequencies and magnitudes of local maxima (peaks) of the LPC- or cepstrum-smoothed spectrum (of a speech signal). While the atom is active (running) the input data is collected and stored in a time-frequency matrix. When the atom is stopped the tracking algorithm is applied to the matrix.

The tracking algorithm tries to create non-crossing formant tracks using a forward/backward search and connection method with a minimum peak-frequency distance criterion. Isolated peaks and chains with a duration shorter than T frames are removed from the matrix. The extracted and sorted formant tracks are stored in the table.

If the <var>F0</var> input is connected, formants tracks are only computed for voiced frames (with <var>F0</var>><code>0</code>).

Table 9: Format of formant data table selected by input MODE

{|
|-
|value of MODE
|values stored in table
(track index: i = 0..N-1, frame index: t = 0,1,..)
|number of cols.
|-
|0
|frequencies:TABLE[t,COL+I] = fi
|N
|-
|1
|frequencies and magnitudes:TABLE[t,COL+2i]=fi and TABLE[t,COL+2i+1]=ai
|2N
|-
|2
|frequencies and magnitudes:TABLE[t,COL+i]=fi and TABLE[t,COL+N+i]=ai
|2N
|}

The bias B is used in the tracking method for the distance computation:

[[File:1234.png]]

with:

fi frequency of formant candidate in frame t
fj frequency of formant candidate in frame t+1
di,j distance of formant candidates

Programmer Guide/SPU Reference/FORMANTS - Revision history

Toni: moved Programmer Guide/SPU Reference/FORMANTS - formant extraction to Programmer Guide/SPU Reference/FORMANTS

Admin: 1 revision: Initial import

193.171.195.8: initial import