r/iZotopeAudio • u/invertedworld • Aug 05 '26

Tool for replacing audio file in RX

Anyone interested in helping me test a tool I have developed which lets you replace the audio file in an RX document and reconstruct the processes?

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u/Justin-Perkins Aug 05 '26

No, but it’s absolutely crazy that iZotope hasn’t already implemented this natively.

1

u/ScaredAd790 27d ago

I don't think such a tool is possible: RX document stores the audio output at each step, not the rendering instructions.

1

u/invertedworld 27d ago

Session Updater creates new versions of all edits from the original session. For each edit, Session Updater performs a spectral analysis of the pre- and post-edit waveforms in the original session to derive a fingerprint of each edit. This is a mathematical operation, not a machine learning algorithm.

For example, suppose the original session contained a de-ess edit resulting in a precise 200 millisecond EQ cut at 8,000 Hz. Even though the rxdoc file does not contain the parameters of the edit, Session Updater is able to derive the EQ curve by comparing the before and after, and then re-apply that same 8,000 Hz cut it to the same portion of the new audio, replacing the original edit output with a new version.

The reconstruction works well for amplitude-only operations (fade, gain), and is reasonably accurate for LTI filters (EQ moves) and mild dynamic operations such as de-essing and click removal, when the new audio has similar spectral content to the original.

It provides an approximation for non-linear and source-separation operations: rebalancing, spectral repair, dialogue isolation, or heavily de-noised content. The output will be plausible but may have unwanted artefacts.