Toni: moved Programmer Guide/SPU Reference/PVANA or PVSYN - phase vocoder I or O modules to Programmer Guide/SPU Reference/PVANA PVSYN

2011-04-28T10:05:54Z

moved Programmer Guide/SPU Reference/PVANA or PVSYN - phase vocoder I or O modules to Programmer Guide/SPU Reference/PVANA PVSYN

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Christian: Text replace - "S_TOOLS-STx" to "{{STX}}"

2011-04-05T15:58:33Z

Text replace - "S_TOOLS-STx" to "{{STX}}"

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	[[File:spu_pvana_pvsyn_circuit.png]]		[[File:spu_pvana_pvsyn_circuit.png]]

	Figure: Functional diagram of <code>PVANA</code> and <code>PVSYN</code> SPAtoms in the framework of the ~~S_TOOLS-STx~~ analysis-synthesis model.		Figure: Functional diagram of <code>PVANA</code> and <code>PVSYN</code> SPAtoms in the framework of the {{STX}} analysis-synthesis model.

Admin: 1 revision: Initial import

2010-11-18T16:31:54Z

1 revision: Initial import

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initial import

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====PVANA / PVSYN - phase vocoder I/O modules====

Phase vocoder analysis.

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

<code>PVANA <var>SIGIN</var> <var>L</var> <var>D</var> <var>I</var> <var>LFFT</var> <var>FMT</var> <var>TYPE WIN WTYPE</var></code>

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

;<var>SIGIN</var>

:The input signal (the name of mono wave item).

;<var>L</var>

:The frame length in samples.

;<var>D</var>

:The decimation length in samples.

;<var>I</var>

:The interpolation length in samples

;<var>LFFT</var>

:The FFT length.

;<var>FMT</var>

:The spectrum format. The following values are supported:
<code>0</code> - complex
<code>1</code> - amplitude
<code>2</code> - power
Note that negative amplitudes are allowed for amplitude spectrum values (<var>FMT</var>==<code>1</code>).

;<var>TYPE</var>

:The algorithm type - 1..amplitude thresholding.

;<var>WIN</var>

:The window name: <code>rectangle</code>|<code>hanning</code>|<code>hamming</code>|<code>blackman</code>|<code>kaiser</code>|<code>bartlett</code>|<code>taprectangle</code>|<code>nuttall</code>|<code>flattop</code>|<code>gaussian</code>

;<var>WTYPE</var>

:The window type:

:<code>normal</code>|<code>dual</code>|<code>tight</code>

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

;<var>A</var>

:The first part of the spectrum (depending on format <var>FMT</var>).

;<var>B</var>

:The second part of the spectrum (depending on the format <var>FMT</var>).

;<var>SR</var>

:The sampling rate.

Phase vocoder synthesis.

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

<code>PVSYN <var>SIGOUT L D I LFFT FMT A B WIN WTYPE</var></code>

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

;<var>SIGOUT</var>

:The name of the shell wave item for signal output (compatible with <var>SIGIN</var>).

See the above atom <code>PVANA</code> for a description of the other input parameters.

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

;<var>N</var>

:The number of frames.

;<var>I</var>

:-1

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

This atom implements the phase vocoder as published in the book "Elements of Computer Music" (R. F. Moore. Elements of Computer Music. Prentice-Hall, Englewood Cli#s, NJ. USA, 1990). The spectrum format (<var>FMT</var>) has to be set to <code>1</code> or <code>2</code> (amplitude or power) for this atom to truly represent a phase vocoder, for only then is phase-unwrapping and differentiation done. If the spectrum format is set to <code>0</code> (complex), this atom implements a channel vocoder. It can be used as an analysis or re-synthesis module for signal time-warping and/or signal modification methods in the frequency domain.

The advantage of the phase vocoder over other analysis/re-synthesis methods is the time and phase synchronicity of the input and output signals. For time-warping, the factor between the input and output timescales is defined by the ratio of the decimation to the interpolation length (<var>D</var>/<var>I</var>). If no timescale transformation should be performed, the values of <var>D</var> and <var>I</var> must be equal. In the current implementation, the "overlap-add" re-synthesis method is included, but not the "oscillator bank" method. This atom can therefore be used for time-warping, but not for frequency-warping.

Conditions for the parameters <var>L</var>, <var>D</var> and <var>I</var>:

<var>L</var> mod <var>D</var> = 0 and
<var>L</var> mod <var>I</var> = 0 and
<var>L</var>< <var>LFFT</var>

The example shows a filter circuit using <code>PVANA</code>/<code>PVSYN</code> for signal I/O. No timescale modification is performed (<var>D</var>=<var>I</var>):

[[File:spu_pvana_pvsyn_circuit.png]]

Figure: Functional diagram of <code>PVANA</code> and <code>PVSYN</code> SPAtoms in the framework of the S_TOOLS-STx analysis-synthesis model.

Programmer Guide/SPU Reference/PVANA PVSYN - Revision history

Toni: moved Programmer Guide/SPU Reference/PVANA or PVSYN - phase vocoder I or O modules to Programmer Guide/SPU Reference/PVANA PVSYN

Christian: Text replace - "S_TOOLS-STx" to "{{STX}}"

Admin: 1 revision: Initial import

193.171.195.8: initial import