FAQ: iZotope RX Audio - Solutions for solving common audio problems

New to RX: Start with RX BASICS

What is the RX Audio Cookbook?

FAQ iZotope RX Audio SolutionsA guide to RX audio common audio problems: The RX Audio Cookbook is designed to provide solutions to your common audio problems. It follows a format similar to most common cooking websites. Each solution, or “recipe,” has a step-by-step description of how to solve an audio problem, before and after audio examples, and either video clips or images to walk you through each step. Before you jump right in, we recommend you explore this RX Basics section. You’ll learn how to get started with the RX application, plug-in pack, and tools and get tips for identifying common audio problems.

What is RX?

iZotope’s RX is software used for repairing, editing, and enhancing audio by interacting with it visually. It is comprised of processing modules and plug-ins, some of which can be used right inside a digital audio workstation (DAW), like Adobe Audition or Avid Pro Tools, or non-linear video editor (NLE), like Adobe Premiere or Avid Media Composer. RX can remove clicks, pops, distortion, reverb, hum, and other noises. It can help with other common audio problems such as inconsistent levels or matching the sounds from different microphones or ambiences. We’ll use and reference the RX product family throughout the RX Audio Cookbook; however, the knowledge and skills you’ll gain by experimenting with these recipes are useful regardless of the DAW, NLE, or product you choose to use.

What Do I Do Next?

  1. Make sure you have the latest RX audio software installed.
  2. Once you have installed the software, follow along with the other articles in the RX Basics section to learn your way around the application.
  3. Use the recipes to find step-by-step directions for help with your audio problems. We’ll also refer to the RX User Manual frequently
  4. Get repairing!

Getting Started with the RX 5 Application

Description:

The RX 5 Audio Editor is a standalone application that provides precision audio noise reduction and cleanup tools for music, film, television, and broadcast. In addition to the standalone application, RX 5 also includes audio plug-ins that can be used within your preferred DAW or NLE, as real-time inserts, or clip/region-based processes.

Getting Started with the RX Plug-in Pack

Description:

The RX Plug-in Pack is a collection of the four essential plug-ins from the RX 5 Audio Editor: De-click, De-clip, De-hum, and Dialogue De-noise. These VST/AU/AAX/RTAS audio plug-ins can be used right within your preferred audio or video editing software, as real-time inserts, or clip/region-based processes.
Dialogue De-noise Reduces the noise floor of recordings, while maintaining the integrity and quality of the audio.
De-clip Reduces analog and digital clipping distortion.
De-click Reduces clicks and pops made from mouth noises, digital errors, grooved media and more.
De-hum Reduces tonal hum from AC line noise, ground loops, HVAC systems and mechanical devices.

Rendering RX plug-ins offline

In any audio or video editing software that offers offline processing of audio clips using plug-ins, you can apply RX noise reduction directly to the problematic clip and render that processing, which will conserve processing power and allow you to tweak settings for each unique piece of audio. In Pro Tools and Media Composer, these would appear under the AudioSuite menu. This can be particularly helpful when a dialogue track is made up of multiple takes with different amounts of noise. By treating the noisiest clips individually with AudioSuite processes, the noise reduction can be tailored to fit each problem. Some hosts (including Ableton Live and Logic Pro) don't currently offer offline processing, but can utilize the RX Plug-in Pack as track inserts.

Using the RX real-time insert plug-ins

All four of the plug-ins in the RX Plug-In Pack can be used as real-time inserts in any mono or stereo audio track. These can be found under the Noise Reduction or iZotope menus in the insert section of the audio mixer in your audio or video editing software. Because of the powerful capabilities of these plug-ins, some of them can introduce latency and use significant amounts of processing power. However, the Dialogue De-noise plug-in is specifically designed to provide high-efficiency, low-latency noise reduction, so that you can use it across multiple tracks without requiring significant amounts of CPU power or delay compensation. The other plug-ins are more resource intensive, and may be best used in single instances or as rendered processes. For example: if you have a recording of a podcast with persistent hum, instead of inserting the De-hum plug-in on that channel, try fixing the whole audio file using the De-hum AudioSuite module, or by processing the audio file and then freezing the track.

5 Tips for Successful Audio Editing and Repair

Description:

Here are some general tips to consider before you begin any audio editing or repair project. 1) Save the original audio file Before making any editing and processing decisions, save out the original, raw, unedited, and unprocessed file. That way you or your collaborators can always revert back to the original version. You may also come back to an edit you made at the end of a long day and find it sounding worse than ever. This is where the original files come in especially handy.
RX Tip If you’re editing inside a DAW, such as Pro Tools, the Playlist feature makes this particularly easy. Just duplicate the playlist of the original file before making any edits to it and render any edits to a new playlist labeled as such. RX allows you to save your work and unlimited undo history as a RX Document File (RXDOC) so that you can revisit your edit decisions later on. Making sure your collaborators have access to your RXDOC files could be helpful too.
2) Compare different settings and listen for artifacts Sometimes it helps to make the same audio repair with different settings. Then you can carefully compare the resulting files and listen for artifacts.
RX Tip RX has a Compare Settings feature that allows you to compare A/B results. Tools such as De-click and De-hum have modes for previewing just the sound that is being removed so you can be sure you’re not removing critical parts of the original sound. Try out the Clicks Only mode in De-click or Output Hum Only option in De-hum.
3) Avoid overediting and overprocessing Noise reduction and signal processing are not without artifacts, and these artifacts can become quite obvious if these tools are overused. Avoid overuse by following these guidelines:
  • Process only the sections of audio that need it. Do this by making small selections so that a processing gesture doesn’t get applied to the entire file unnecessarily.
  • Complement the project, don’t distract from it. A little background noise may sound more natural to your audience than the characteristic sound of overprocessing.
  • Process multiple times with conservative settings instead of a single time with extreme settings. You may also find that processing a number of smaller sections yields better results than processing one large section all at once. This is particularly useful when removing substantial amounts of noise.
4) Document your edit process Referring back to documentation will help you improve your workflows and solve problems more quickly and efficiently in the future. For forensics work, documentation is often a required deliverable in addition to a best practice.
RX Tip RX automates this process by allowing you to save module-specific presets and RXDOC files. If you’ve figured out a solution and want to document it, use the undo history tool to retrace your steps.
5) Keep the ears rested and the mind open Audio editing and restoration work requires a lot of focus on subtle details. Taking breaks will help you return with a fresh mind to see and hear the bigger picture.

Post Production

Repairing a Distorted Audio Track

Have you ever been in the middle of a great sounding take, but suddenly the preamp or interface gets overdriven and the take is unusable? The De-clip module in iZotope’s RX audio repair software can help rescue tracks that were recorded too hot by redrawing squared off waveforms.

How to Remove Background Noise from Dialogue Recordings

With location dialogue tracks, a steady background noise can make it difficult to bring quiet scenes forward in the mix without also boosting the distracting noise floor. Using the Corrective EQ module before the Dialogue De-noise module can help mitigate this constant noise and allow the voice to be heard more clearly and prominently without losing the ambience of the scene.

How to Remove Isolated Background Noises from Dialogue Recordings

Random sounds behind a dialogue track—such as beeps, squeaks, sirens, or coughs—can distract from the storytelling. Instant Process mode in iZotope’s RX audio repair software is the easiest way to Attenuate or Replace noises by selecting them on the Spectrogram and immediately applying the settings from the Spectral Repair module.
Removing Mouth Clicks from Audio Recordings
When recording a voiceover or vocal track with a sensitive microphone, we can start to hear the mechanical noises of the mouth, and they can be distracting. Mouth clicks and smacks can be removed easily from a recording using the De-click module in iZotope’s RX audio repair software, without affecting intelligibility.
Removing Plosives from a Recording
Plosives are strong blasts of air that create a massive pressure change at the microphone's diaphragm, and happen most often with strong p, t, k, and b sounds. iZotope’s RX 5 Advanced can intelligently remove these from your audio using the De-plosive module.
Removing High Frequency Buzz and Interference
Some video cameras, portable recorders, and audio interfaces can impart annoying high frequency noises that could ruin your audio. The Spectral De-noise plug-in in iZotope’s RX audio repair software can help clean up your audio and preserve your tracks.
Removing Audio Hum with iZotope RX
Hum is often caused by lack of proper electrical ground. For this problem, we’ll use multiple modules in a particular order to mitigate it. The De-hum module in iZotope’s RX noise reduction software includes a series of notch filters that can be set to remove both the base frequency of the hum (usually 50 or 60 Hz), as well as harmonics that may have resulted. Then we can use the Spectral De-noise module to address additional buzz above those harmonics.

Fixing Wireless Dropouts in Production Audio

RF Hits (dropouts in the signal from a wireless mic) are a common issue in production dialogue. Using theAmbience Match and Spectral Repair modules in iZotope’s RX audio repair software, you can fix some of these issues, even if they’re right on top of the dialogue track.

Removing Digital Clicks and Pops

Sync problems and ground loops between a computer and audio interface can create an audio track mired by digital clicks and pops. The De-click plug-in in iZotope’s RX audio noise reduction software can effortlessly remove digital errors like these and preserve an otherwise unusable audio track.

How to Remove Cell Phone Interference from Audio Recordings

It is common to find recordings mired by GSM cell phone interference -- a “dit dit dit” or buzzing sound from the RF transmission that can creep into analog circuits. The De-Click module in iZotope’s RX audio noise reduction software has a preset built specifically for mitigating this problem.

How to Clean Up Audio from a Phone Recording

Recordings made off of a telephone line can be heavily distorted and difficult to understand. The De-clipmodule in iZotope’s RX software is designed to help repair analog and digital distortion by redrawing squared-off waveforms.

Reducing Reverb with the RX De-Reverb Module

The De-reverb module in iZotope’s RX audio repair software can help reduce reverb components immediately surrounding source audio where conventional tools, such as a noise gate, are less effective. Also the module can boost the source audio to increase intelligibility and presence. In this recipe, we will look into using the De-reverb module to reduce the reverb without losing the character of the dialogue or ambience.

Matching Room Tone and Ambience

iZotope’s RX 5 Advanced takes iZotope’s revolutionary Ambience Match technology and makes it available as an AudioSuite process right inside of Pro Tools. This is perfect if you need to fill a gap between two pieces of dialogue, recreate background ambience for a scene, or match ADR to production dialogue. RX can identify the room tone underneath content and seamlessly replicate it.

Sound Design Inside of iZotope RX

While the RX Audio Editor is often used as an audio repair tool, it can also be used as a powerful tool for expanding your sound design palette. Create exotic sound effects quickly using the unique visual editing capabilities and processing modules in RX.

Creating Futz Audio Effects

‘Futz’ audio generally refers to highly processed dialogue tracks which make the audio sound like it’s coming from a telephone, a small speaker, an alien spaceship or whatever the story demands. By making frequency selections on the spectrogram inside of the iZotope’s RX audio repair software, we can apply radical filtering effects to create the sense that the actor’s voice is coming through a telephone, or anything else you can imagine!

How to Fix Audio Clipping

Clipping in dialogue recordings is often a consequence of a lack of headroom in the recording equipment. The De-clip module in iZotope’s RX audio repair software is designed to help repair analog and digital distortion by redrawing squared off waveforms.
Audio productionAudio repairFaqIzotopePost productionRx pluginRx5

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