Freqresponse

Freqresponse is a routine used by several others to prepare a spectrum for use with routines that filter, compress or limit. The response can be normalized or not depending on the needs of the routine which will use the response.

Freqresponse is a standalone instrument, but is also embedded in several other instruments such as Filtdeviator w/ Analysis.

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Analysis Channel(s)
Analysis Frames per Second
Analysis Method
ASCII Spectrum File
Average Amplitude Weighting
Begin Time in Seconds
End Time in Seconds
EQ - Low Shelf Gain
EQ - High Shelf Gain
EQ - Low Shelf Frequency
EQ - High Shelf Frequency
EQ Normalization Bypass
FFT Length
Frequency Response Printout: High Cutoff Frequency in Hz
Window Size in Samples

 

Analysis Channel(s)

Determines which channels will be analyzed. 0 equals all channels.


Analysis Frames

This controls how often the phase vocoder will perform an analysis on the signal. It is a translation of the classic decimation control that specifies how many samples to skip between analysis frames. More frames increases the resolution of time but decrease speed. 200 frames per second is a good reference point. If you expand time you should increase this proportionately to maintain about 200 or more frames per second.


Analysis Method


ASCII Spectrum File

A file consisting of frequency/amplitude(dB) pairs, one per line. Some routines such as Centroid can output an ASCII file suitable for use here.


Average Amplitude Weighting


Begin Time in Seconds

The time, in seconds, at which to begin processing the soundfile.


End Time

The time, in seconds, at which to stop processing the soundfile. 0 or less is equivalent to the duration of the soundfile.


Low/High Shelf Equalization

Equalization has been provided at various points in routines to allow for the needed adjustment of spectra. The EQ consists of low and hi shelf segments, whose width is adjusted through control of the shelf breakpoint frequency. The region between the shelf segments is represented by a linear decibel gradient between the decibel levels of the two shelves. Some routines implement the EQ before pitch changes, others after. EQ placed before pitch changes (pre-transpose/shift) will cause the EQ to be transposed with the pitch changes, whereas afterwards (post-transpose/shift) will keep them fixed as shifts and transpositions occur.

Low Shelf Gain

Determines how the amplitude of sounds below the low shelf frequency will be affected.

High Shelf Gain

Determines how the amplitude of sounds above the high shelf frequency will be affected.

Low Shelf Frequency

Determines the frequency below which the low shelf gain will be used.

High Shelf Frequency

Determines the frequency above which the high shelf gain will be used.


EQ Normalization Bypass

This parameter controls whether or not the analysis result will be normalized. 0 means normalization will occur (no bypass), 1 means it will not (bypass).


Frequency Response Printout: High Cutoff Frequency in Hz

During execution, frequency response data is printed. Frequencies over this cutoff will not be printed. Set to 0 to turn all printing off.


FFT Length

The FFT size must be a power of 2. Larger FFT sizes resolve frequencies better but transient behavior more poorly. Choose your FFT size according to the sound you are working with. A size of 1024 or 2048 works well in most cases.


Window Size in Samples

The window size is a less opaque parameter; like the FFT, it must be a power of 2. Windows twice the size of the FFT work well. Larger window sizes may resolve frequencies better. Specifying 0 for the window size will automatically set the window to twice the FFT size.