Purpose

Spectrum ISTFT turns spectrum frames back into stereo audio using an inverse short-time Fourier transform with overlap-add. It is the exit point of a frequency-domain chain that starts with Spectrum STFT.

Use

Wire a spectrum ring into in and route out into an effect chain or Device Out. Place Spectrum ISTFT after Spectrum STFT and any spectral processing between them. Match Windowsize, Hopsize, and Window to the Spectrum STFT that produced the frames so the audio reconstructs cleanly.

Inputs and outputs

• Input 0: in accepts a stereo spectrum ring. It is required.
• Output 0: out emits stereo audio.

Controls

• Windowsize: synthesis window in samples: 512, 1024, 2048, or 4096. Set this to match the STFT.
• Hopsize: window advance as a fraction of the window: quarter, half, full, or eighth. Set this to match the STFT.
• Window: synthesis window shape: hann, blackman, or rect. Set this to match the STFT.

Notes

• Output is stereo.
• Reconstruction quality depends on matching the STFT settings and using an overlapping hop such as quarter or half. A full hop has no overlap and reconstructs less smoothly.
• If the result sounds gated or thin, check that the three settings match the source Spectrum STFT.

Ports

Inputs

• in row required
  spectrum_stereo_v1

Outputs

• out row
  audio_pcm_f32_stereo_v1

Parameters

Windowsize (Windowsize) Menu op('spectrum_istft').par.Windowsize

Default:

1024

Options:

512, 1024, 2048, 4096

Hopsize (Hopsize) Menu op('spectrum_istft').par.Hopsize

Default:

quarter

Options:

quarter, half, full, eighth

Window (Window) Menu op('spectrum_istft').par.Window

Default:

hann

Options:

hann, blackman, rect