Center Extract

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Table of Contents

Overview

The Center Extract module preserves (using Keep Center) or removes (using Keep Sides) the center channel of a stereo file. Extracting the center will retain the center of a stereo field and attenuate everything on the sides, such as signals panned to the left or right. See the Use Cases section below for more contextual examples and additional information about Center Extract processing.

Controls

Center Extract interface
  • KEEP CENTER: When the signal you want to preserve is even in both channels and noise is uneven between channels, extracting the center can remove a lot of noise.
  • KEEP SIDES: If you want to preserve the wide stereo information and remove the center information, you can keep the sides of the signal instead.
    • ALGORITHM: Two different algorithms are available:
      • TRUE PHASE: Cancels the center with phase information and retains the original panning of the sides.
      • PSEUDO PAN: Extracts the side information and artificially stereo-izes it into two channels.
  • REDUCTION STRENGTH: Controls the level of the preserved signal. Lower values will retain more information, higher values will discard more information.
  • ARTIFACT SMOOTHING: Helps to reduce or eliminate the “musical noise” that is often characteristic of FFT-based processing. Musical noise can be described as how something may sound underwater. Increase this slider if your output sounds watery, but decrease it when too much smoothing makes your audio sound dull.

    What is an FFT?

    Fast Fourier Transform: a procedure for the calculation of a signal frequency spectrum. The greater the FFT size, the greater the frequency resolution, i.e., notes and tonal events will be clearer at larger sizes. However, when using FFT-based processing, the more audio you remove from your source, the more likely you are to create undesirable artifacts.

  • DRY MIX [%]: Controls the amount of unprocessed signal mixed into the processed signal. Useful for reducing artifacts introduced by processing by preserving the original characterisitics of your audio.

Tip: Use Azimuth before Center Extract for best results

It is often a good idea to make sure stereo channels are balanced by running Azimuth correction before using Center Extract.

Notes on Center Extract Availability

  • Center Extract is not available when Composite View is active.
  • Center Extract processing is not available on mono files. The nature of Center Extract processing makes it unapplicable to mono files because they lack stereo field information.

Use Cases

  • Using Center Extract as an alternative to Mid-Side Encoding: Center channel extraction will preserve a stereo image if the side channels are retained. This can make it more desirable in some cases than Mid-Side encoding (which would sum left and right hard pans into one channel).
  • Use Keep Center to Reduce noise in stereo files transferred from a mono source: A mono record transferred to a stereo tape would have side channel noise that would be suppressed by extracting the center channel using Keep Center.
  • *Use Keep Sides to Remove vocals from a stereo recording:
    • The lead vocal track, in many popular mixes, is typically panned to the center of the mix. Panning something to the center results in equal information being present in the side (Left and Right) channels.
    • Using the “Keep Sides” processing mode will retain the unique side channel information present in a file, and reduce the Center channel.
    • This is useful for karaoke-style removal of vocals from a song, especially because the process results in a coherent stereo image.

RX 9.3.0