Home Non-Linear Editors: How To's How to Prime Your NLE Audio Channel for Mixing: Video Edition

How to Prime Your NLE Audio Channel for Mixing: Video Edition

Prime NLE channels for mixing in post
Mixing in post

To prime your NLE Audio Channel do you apply your audio effects to an audio clip or an audio channel? The answer is, of course, it depends entirely on what you’re trying to achieve.

Special effects might be applied to certain scenes, certain clips – whereas more global tasks such as equalising, sweetening, enhancing and mastering ADR would require effects placed on an entire audio channel.

In a word, audio channels give you consistent and coherent processing in post to help unify audio collected from different sources.

It’s true to say that preparing channels to better receive audio clips, no matter the source or content, is a vital time saver and not only that, can be a quick fire way to ‘standardising’ a multitude of clips into one coherent sonic space – every sound is sat in one room, within the same four walls and not spread out over various psychoacoustic planes.

Set Up A Channel EQ Template

We use templates to save time but also to unify our workflow and create succession. The way we create is ‘our’ way, and over time we build strong methodology to that effect.

EQ, being your forever-friend in post, can be used to very subtly clean, contour, polish and embellish within audio channels, not just individual clips. For those new to the world of Equalisation there are a number of post production tools at hand that EQ and contour your audio for you.

Audio post for video EQ template
Useful EQ settings for any channel receiving average quality audio soruces to embolden, tame and control
1Insert an EQ on your audio channel, or set up your in built channel EQ
2Cut all frequencies below 50Hz by using the ‘Hi pass’ band on you EQ. Depending on how your ears perceive the very low end of the audio source, bring the centre frequency up to 100Hz
3The effect is an ‘unclogging’ creating a subtle openness especially in location recordings and environmental ambience.
4The effect can be perceived as an ‘unclogging’, creating a subtle openness especially in location recordings and environmental ambience

Warmth, Tone And Punch

Warmth is a generic word for the fullness and body in audio sources. It’s logical to say that subtle warmth achieved across each audio channel will result in a warmer final mix but it can also result in a more muddy, unintelligible mix.

With EQ, we often require a small ‘shelf‘ lift in the low frequencies that sit above the sub frequencies such as 80Hz to 180Hz.

This is where the ‘body’ of a rapturous roll of thunder lies, this is the thickness in the ‘thud’ of a suicidal corpse or of a felled tree.

Warmth, Tone, and punch in video audio
1Engage a band in your EQ and set it to a ‘low shelf’. Between 80Hz and 180Hz. Your shelf should roll off, finishing around 200Hz
2With channel EQ, subtlety is key. Set your shelf EQ from between +1.5dB and +3dB only
3For extra punch, or ‘body’ you can add a ‘bell‘ boost in the low range from 60Hz to 100Hz
4The ‘bell’ shape is a curve that centers around one particular requency and is much more accurate that the long flat ‘shelf’ type EQ
5Anything from +1dB to +6dB can improve on thin, porous sounding audio, depending on the source material.
6Be cautious when using strong, sharp ‘bell’ curves boosting frequencies on audio channels as they tend to sound very unnatural and over-processed.
7 As a rule, use broad, subtle lifting and cutting on audio channels.

Compression And Control

Compression is available as a built-in audio channel effect in most NLEs for a reason.

The dynamic reduction of loud signals needs to be automated by compression, otherwise we would be lumbered with the arduous task of manually keying in level reduction as that tree fell, or thunder clapped across the shivering torpor.

It’s worth mentioning at this point that the effect of compression is a sensation more than a sound. For example, 10 channels each with with heavy compression settings will ‘feel’ very different (almost suffocated) to channels where no compression is used.

Compression for NLE audio Channel
1Insert a compressor before the EQ plugin on your audio channel, or engage the in-built channel compression
2One benefit of the compressor is called ‘makeup gain’. It adds character to audio by lifting levels back up after compression reduction
3Set your ‘Attack‘ to slow – somewhere between 0.30 and 0.80 seconds.
4Set your ‘release‘ to fast – somewhere between .5 and 50 milliseconds
5Set the ‘makeup gain’ on your EQ plugin to +1.5dB
6Set your threshold using your ears. During playback slowly lower the threshold control until you hear the dynamics (freedom, airyness, openness) of the audio compress and reduce.
7Compressors reduce audio level dynamically during playback. Try to aim for no more than -3dB to -6dB reduction on average.
8If you are compressing much more than this, then consider applying compression to individual clips on a case by case basis and not as a global channel effect.

Stereo Sound Stage

When mixing a number of audio sources together – dialogue, street ambience, car horns, footsteps, weather sounds, dessert rain falling on corrugated cabins, the war cry of a rogue interstellar mercenary dropship, for example, it’s important to pay attention to the available sonic sound stage.

Setting predefined pan positions can help to separate sounds, and the frequency spectrum they are comprised of allowing you to see and locate each before you begin EQ and compression.

Will a cyclist moving at speed from left to right across a scene need panorama? With a stereo recording, no – that psychoacoustic movement is embedded inside the stereo information of the audio recording.

Mono sources will need more care, and also creativity.

1Set your pan control no more than 85 full left or 85 full right as extreme panning can sound very unnatural to the ear
2For mono sound sources with no apparent visual location, such as a bird chirping, a plane passing overheard, a fracas in some distant part of the city, pan can be set up it’s position within the stereo field.
3By making a copy of your mono audio channel, effectively doubling your audio source, you can create a ‘Pseudo Stereo‘ which can mimic stereo imaging
4Pan channel 1 to the left 85
5Pan channel 2 to the right 85
6Set channel 1 to delay playback 20ms or more
7Although Pseudo Stereo can sound quite cheap compared to natural stereo when used very subtly, way back in a mix, it can be a colourful psychoacoustic ‘bed’ for a richer, more immersive sound stage.
8Sounds don’t often move the way objects do. Panorama is about binaural psychoacoustic location and so, during playback, use your ears to place sounds in natural spaces
9Use your ears and your OWN audio analysis to select EQ frequencies to process
10The last step is to use the output gain on the EQ plugin to give back audio level
11.Set the EQ plugin output gain somewhere between +1.5dB and +3dB

Workflow Wins

There’s a large emphasis placed on workflow in post and while setting up audio channel templates does address this, it should part of a larger, more personal methodology. Take away some or just one of these techniques and inter-lock them into your own daily practices to help streamline your NLE audio channel.

I hope this article helps you approach audio channels and audio clips differently, priming your project ready for audio post production… let us know how you get on!