Reworking a Master

It’s been a while since I last posted. The last few years have been difficult. I was compelled to tend to my Dad Sonny. He passed away on April 26. I’m obviously heartbroken. However he would have wanted me to move forward and continue to share insight …

I recently listened to a program consisting of a group of “Podcast Editors.” Group members are also business owners providing podcast production services for a wide range of clients. 

I believe a few (or all?) group members were trained by Chris Curran who runs Podcast Engineering School

The business owners disclosed they are often in a position (for various reasons) to outsource work. All good. However I thought to myself if I were to consider outsourcing work – what method(s) or criteria would I implement to assess applicant talent and/or proficiency?

A top level requirement would be obvious: the ability to effectively edit speech/dialogue and optimize intelligibility. DSP audio processing proficiency (and tool accessibility) would be prerequisites as well.

Let’s have a look at a specific “test” scenario that I might propose for applicant assessment:

A new self producing client’s podcast has been accepted by an imaginary powerhouse spoken word audio network. The network has strict audio submission compliance requirements. WAV files are to be submitted. The network will create the lossy distribution copies. 

The client seeks assistance conforming the following self produced program as measured:

Attributes: -18 LUFS [stereo], -0.8 dBTP. LRA: 3 LU

*** In my opinion the example above visually indicates careless mastering. The narrow headroom may pose difficulties if added gain is ever necessary. It doesn’t sound inherently bad. However it’s not properly optimized for submission to our imaginary network.

Client/Network Compliance Requirements: 

-16 LUFS stereo (tolerence: +/- 1 LU). Ceiling: -2.0 dBTB. LRA < 6 LU

Client’s Specific Instructions:

• Integrated Loudness target compliance for network (source audio needs to be bumped up)

• Compliant True Peak ceiling and prevention of excessive limiting and/or induced distortion 

• Avoidance of breath elevation and noise due to gain offset requirements

• Retention of reference fidelity

For the record I’m not going to disclose the source of this audio. There are many similar examples out there.

Here’s is my re-produced output as measured:

-16 LUFS, -2.2 dBTP. LRA: 2.9 LU

in the zoomed selection below notice there is no visual indication of an elevated noise floor. Also overly aggressive dynamics processing/limiting has been avoided. Fidelity is excellent.

Final Thoughts

From a general perspective the client’s original source audio is suitable for a typical podcast regardless of the visual attributes of the waveforms. However that assessment is not the purpose of this article. The question is – are you capable? Do you think you can pass my proposed test? Can you satisfy our imaginary client?

Be aware there’s allot more to this than you may assume. Compression is only one aspect of my optimization process (of course we can discuss). Also note this remastering scenario does not include accessibility to discrete mix stage audio assets.

* * *

When you add definitive compliance requirements to any workflow the level of complexity elevates. This is especially true in situations where you as an engineer may be be called upon to “fix” audio masters that my not be suitable or properly optimized for downstream program preparation and distribution.

-paul.

Audio Plugin for Podcast Post and Streaming

An obscure and rarely mentioned audio plugin by Waves exists that is well suited for Spoken Word processing, Live Streaming, and Podcast Post Production – MaxxVolume.

Back in 2012 I documented my initial interest and subsequent purchase of MaxxVolume. I paid $149 for the plugin, on sale at the time over at DontCrack. I believe the original selling price was $400. It’s currently available for $49.

MaxxVolume is a multi-stage dynamics processor. The plugin features High/Low Level Compressor modules, a Downward Expander, a Leveler stage (aka RMS compressor/AGC), a user selectable Loud/Soft ARC flag, and a global Output Gain control.

Let’s explore the attributes of MaxxVolume …

Leveler

The Leveler fader value defines the AGC threshold and target. The inherent processing uses long attack and release times similar in attributes to an RMS compressor to effectively maintain consistent levels over time. Basically, automatic gain-riding initializes when the passing signal level exceeds the threshold and correlated target.

The Energy Meter’s internal chain placement is located after the Leveler processing and before the plugin’s remaining dynamics modules.

Gate

The included Gate is essentially a Downward Expander. When the passing signal level drops below the defined Threshold fader setting – attenuation is initialized. Note the general difference between a Gate and Downward Expander: a Gate applies a sort of hard mute. A Downward Expander applies a much more gradual transition between audibility and attenuation.

High Level Compressor

A traditional compressor applies gain reduction (dynamic range compression) when signal levels exceeds a defined threshold. In general the operator may (1) elect to work with the compressed/attenuated audio, or (2) apply makeup gain to compensate for the resulting attenuation.

The MaxxVolume High Level Compressor is controlled by a single Threshold fader. Gain reduction is indicated on the associated meter when the signal level exceeds the defined threshold. Automatic makeup gain is applied to compensate for active gain attenuation.

The Gain fader located in this module controls the maximum output signal level. This setting is NOT a ceiling based compliance limiter!

Low Level Compressor

This module basically applies upward soft-knee compression. It allows the operator to add a specific amount of gain to the passing audio when it’s level drops below the user defined threshold. The associated Gain Meter indicates the amount of makeup gain.

Note: The High and Low Level Compressor threshold settings are displayed within the previously mentioned Energy Meter.

The Soft/Loud Flag

This flag sets the attributes for the Waves proprietary ARC (Auto Release Control).

ARC, as described by Waves:

“The ARC algorithm is designed to dynamically choose the optimum release value for a wide-ranging input. ARC reacts much like a human ear, and can produce significantly increased RMS (average) levels with excellent audio clarity.”

In essence – the Loud setting uses shorter Release times resulting in elevated loudness. Conversely the Soft setting uses longer Release times resulting in a softer output.

Output Meter

This meter indicates Peak Amplitude and potential inherent clipping.

Setting it Up

(1) Disable the Downward Expander (you will use it eventually). By the way – all Threshold faders support deactivation. Simply click the encapsulated yellow indicator located on each fader.

(2) Set the ARC flag to Soft and define a Leveler threshold.

(3) Adjust the High Level Compressor to (1) compress dynamics, and (2) compensate for the attenuated signal level.

(4) Apply 5 or 6dB of Low Level Compressor module gain. Tweak the module Threshold and readjust gain accordingly. Be cautious when applying excessive gain at levels above the defined threshold. Pay close attention to the noise floor.

(5) Lastly, adjust the High Level Compressor Gain to optimize the output.

If you are running Adobe Audition – use the Preview Editor to reflect the results of your settings relative to the source. The updated waveform will indicate the results of the applied settings. Observe the processed dynamics and evaluate the audible consistency of the average loudness over time.

Of course visual attributes of any waveform are meaningless if the sound quality is compromised. Use those ears to achieve optimum results.

Notes

It’s important to establish a clear understanding of each processing module and the interactive processing results.

If necessary – apply Broadband Noise Reduction and/or Phase Rotation before MaxxVolume in your signal processing chain.

Remember – the High Level Compressor Gain does not establish a hard limited compliance ceiling! You will need to Insert a post compliance limiter. I recommend the following limiters: ISL by Nugen Audio and Elixir by Flux. TrackLimit by DMG Audio is also a worthy consideration.

Specialized Use Cases for MaxxVolume

• Intelligibility optimization

• Pre-Loudness Normalization dynamics processing

• Live Streaming

• Live Venue processing

Personal Perspective

– -> On multiple occasions I’ve expressed how it can be difficult working with non-scalable audio plugins on high-resolution monitors. I am a proponent of defining specific numerical setting values on supported plugins in order to fine tune parameters. Legacy UI designs offered by various developers generally exhibit fuzzy text and difficult to read values. These difficulties are prevalent when running monitor resolutions higher than 1920×1080 (I run a 4k compatible monitor at 2560×1440). In essence, viewing MaxxVolume’s fader values and additional indicators can be visually challenging.

– -> Be careful when using the Low Level Compressor. Excessive gain will elevate breaths and boost the audible noise floor.

– -> An integrated compliance limiter would be useful. As it stands, the insertion of a down-stream limiter is vital.

-paul.