In this article we’ll look at my top 5 utility plug-ins for audio post. These are plug-ins which can assist in carrying out routine tasks which you’re likely to encounter during the post-production process. It should be noted that this is a list of my personal choices and it is not intended to be a definitive top 5 but rather my top 5. I’ve also included a couple of bonus choices at the end of the list which may not be strictly utility plug-ins since they provide extensive controls and processing options but I’ve nevertheless listed them because they’re integral to many of the mixes I do.

Nugen Audio VisLM

It goes without saying that loudness metering is an essential part of the post production process. A plug-in which provides metering for a variety of different specs is critical, and there are numerous solutions out there which provide the functionality required. If I had to narrow it down to just one, my choice would be Nugen VisLM. As you’d expect, it provides metering in various standards based on the ITU-R BS.1770 standard including EBU R128, ATSC A/85 and the dialog-gated Netflix spec. Importantly, the information shown in the plug-in is displayed very clearly, with the Loudness History window charting the loudness of your content over time and highlighting in red any excessive peaks. Of course, the Momentary, Short Term, Integrated and True Peak values are displayed too.

One feature which sets VisLM apart from most other loudness metering plug-ins is the integration between the AudioSuite and real-time versions of the plug-in. If you have existing content which you need to measure the loudness of, you can use VisLM AudioSuite to analyse the loudness offline and then export this using the little yellow button at the bottom of the plug-in. This loudness information can then be imported into the real-time version of VisLM using a corresponding import button. This means that you can build a loudness measurement of an audio file using the offline capabilities of AudioSuite and then make adjustments and continue to meter it in real-time without the need to play the entire duration of the file.

Nugen VisLM is resizeable and various parts of the display can be toggled on or off as required, making for a more efficient use of screen space. It provides a timecode mode where loudness data is linked to timeline position, making it possible to ‘overdub’ sections of the loudness measurement without the need to play the entire thing through from start to finish.

For cases where you need to conform existing audio mixes to current loudness standards, Nugen provide another plug-in, LM-Correct. This measures and corrects audio quickly and easily and can also be used as a final ‘back-stop’, ensuring that finished files are within specification and performing an in-place fix where errors are found.

Sound Radix Auto Align Post 2

Working with multiple microphones and trying to mix them together can inevitably cause issues with phasing and comb filtering. The timing variances between lav and boom mics often make blending them together quite troublesome. Fortunately, Auto Align Post 2 from Sound Radix provides an easy solution by allowing dynamic time alignment of moving location microphones. One mic can be selected as the reference and the others are then precisely time aligned to it.

Auto Align Post 2 introduced some important new features. It has native Adobe Premiere Pro compatibility, which means that you can time align audio sources at the point of editing, before the audio even gets to audio post. Another great feature of Auto Align Post 2 is the Spectral Correction module which detects and dynamically corrects frequency-dependent phase shifts to achieve significantly improved spectral alignment, especially in situations where high pass filters which induce phase shifts have been used on the boom mic.

Avid X Form

Pro Tools users will be familiar with X Form as a high quality time compression/expansion and pitch-shifting plug-in. Aside from its use as a creative audio processing tool though, X Form also has a more utilitarian use when audio pull up or pull down is required. There are occasions when the frame rate of a project needs to be changed. This can happen when converting between mediums, for example film to TV or from one region to another. Frame pull up and pull down is a complicated topic and there are multiple ways to achieve it but when a simple speed change up or down is required, X Form has the presets you’ll need to achieve this with minimal detrimental effect on the audio.

To give an example of how this might be used, I recently worked on a documentary which had been shot at 25fps. I completed the audio mix and sent it to the director. He then informed me that in addition to the 25 frames per second version he would also need a version at 23.976fps for inclusion on a Blu Ray. This was accomplished by slowing the video down by 4.1% in Adobe Premiere using the Interpret Footage feature to specify the new rate. To bring the audio down by the same amount I used the ‘PAL to NTSC TCE -4.1% preset in X-Form to slow the audio down by a corresponding amount while retaining the pitch. X Form includes presets for all common pull up and pull down rates.

Dither

If there’s a plug-in category which is important but not in the least bit exciting it’s dither. Dithering is the process of adding a small amount of low level random noise to a signal in order to randomise quantisation error and distortion when reducing the bit depth of audio. We often associate it with the process of creating a 16 bit version of a mix which was recorded and mixed at 24 bit. In actual fact though, you should ideally also be applying dither even if you’re bouncing to 24 bit. DAWs operate internally at a much higher bit depth than the audio itself. In Pro Tools the mixer is 64 bit floating point and the signal paths between plug-ins are 32 bit floating point. Even if your audio is 16 or 24 bit, as soon as you make any adjustments whatsoever, whether it’s a level change, panning or any form of plug-in processing, you’ll be tapping into the greater internal bit depth of the DAW.

Many dither plug-ins, including Acon Digital Dither, allow you to specify a target bit depth of 24 bit. Although quantisation error in a 24 bit bounce would be at an extremely low level (about -144dB), it’s nevertheless good practice to apply 24 bit dither for the absolute best possible result.

Noise shaping can also be applied in order to make the dither noise itself less audible by equalising it so the more prominent part of the dither signal is in a frequency range to which our hearing is less sensitive. This will be more noticeable at lower bit depths, particularly if you ever have cause to dither to 8 bit.

I’ve used Acon Digital Dither as an example here since it provides options for dithering to 8, 12, 16, 20 or 24 bit but there are plenty of other dithers which offer a 24 bit dither including MBit+ from iZotope and the dither built into FabFilter’s Pro-L2 limiter.

iZotope RX

While not strictly a plug-in, iZotope RX provides several different processing modules within its Utility section. These include azimuth, dither, gain, normalise, phase, signal generator and resample, to name a few. The Resample module provides high quality sample rate conversion with control over how the filtering is applied. For critical sample rate conversion it gives measurably better results than the conversion provided by most DAWs. If you want evidence of this, take a look at this sample rate conversion quality comparison tool.

In addition to this, the Batch Processor lets you load multiple files from your machine, apply entire Module Chains to the entire batch, then export in as many file formats and bit depths to as many locations as you need. While RX is typically used for noise reduction, the Batch Processor can also be used for any of the Utility functions RX provides. This makes it a good option for the resampling, dithering and export of large numbers of audio files. Files can be output in a range of formats including WAV, FLAC, AIFF, OGG and MP3. 

Additional Plugins

In compiling this list, several other plug-ins sprang to mind which probably don’t really fit into the category of ‘utility’ plug-ins but I use them to carry out tasks which are essential to some of the projects I work on and they perform functions which fall outside of the categories of EQ, dynamics and reverbs so I’ve included them below as ‘bonus’ choices.

Synchro Arts Revoice Pro 4

When editing ADR there are usually timing issues which need to be addressed. Revoice Pro 4 from Synchro Arts brings together advanced timing and pitch alignment technology, making the process of aligning ADR with the original location dialogue a simple and straight forward process.

While Revoice Pro is actually a standalone application, audio can be sent to it from Pro Tools using the included Revoice Pro 4 Link AudioSuite plug-in. When used with DAWs supporting ARA2, transfers are even easier and any changes you make in Revoice Pro automatically appear in your DAW.

Using the APT (Audio Performance Transfer) algorithm, Revoice Pro 4 can apply not only the timing but pitch, volume and vibrato of one track to another. Controls for Formant shifting are also included. These features may be more intended for use in music production but they can still be useful creatively in post when manipulating dialogue.

If you don’t require some of the advanced features of Revoice Pro, but still need to time align ADR, Synchro Arts offer a more cost effective solution in the form of VocAlign. This operates as a plugin within your DAW and is a great solution if you just want to get ADR time aligned quickly with minimal effort or adjustment of parameters.

See what Mike Thornton thought of it in his article Synchro Arts Revoice Pro 4.3 Smart Align Mode Tested On ADR.

Nugen Audio Halo Upmix

For upmixing stereo stems or repurposing archive material, Nugen Halo Upmix is a great tool which produces natural sounding, coherent results in formats up to 7.1 surround sound. An optional 3D extension adds Dolby Atmos bed track (7.1.2) and Auro 3D (7.1.4) compatibility, and Ambisonic outputs.

The Halo Upmix algorithms preserve the character of the original audio without adding any artificial reverb, chorus or delays and the ‘Exact’ mode ensures that the relationship between the original, upmixed and down mixed versions is maintained which can be critical in situations such as TV repurposing.

Halo's advanced centre channel extraction offers a unique level of control - including neural network-based dialog extraction, which is useful when dealing with intricate mixes where no access to the original stems is available.

Halo Upmix supports upmixing to a variety of formats including LCR, 3.1, 4.0, 4.1, 5.0, 5.1, 6.0, 6.1, 7.0 & 7.1 and, with the 3D Immersive Extension, 7.1.2 and Ambisonic.

Final Thoughts

So that’s my top 5 with a couple of additional bonus plug-ins at the end which I felt were well worth a mention even though they technically carry out tasks beyond the scope of what could perhaps be considered a utility plug-in. Everyone has their own favourites and it really depends on the type of projects you work on regularly.

What are your favourite utility plug-ins for audio post? Share your thoughts in the comments.