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What Is Audio Post Production?

Alex Gregson

In this article, we will present a guide to audio post-production covering topics like pre-production, the various job roles, session preparation, dialogue editing, sound effects, sound design, foley, reconforming and mixing.

What Is Pre-Production?

Pre-production covers all of the sound-related activities that need to be completed before the camera starts rolling. It typically will include the following tasks: 

  • Script Analysis - Reading and annotating the script to form a basis of ideas that the Director can critique and build upon.

  • Building a Sound Team - The Sound Supervisor may get involved with building the team for Post Production and in some cases Location Sound. It is also important to build relationships between the whole team here.

  • Location Visits - Location Sound Recordists and/or Sound Supervisors will want to be present during location visits to troubleshoot sound issues and to look for opportunities for recording sound effects.

  • Spotting Session - The Supervising Sound Editor/Sound Designer will have a meeting with the Director, to perform a thorough creative analysis of the film and it's required sound assets.

  • Custom Sound Effects Recording - The Sound Effects Recordist will capture sounds that add authenticity and character to the film. These recordings can be taken from a variety of places, both at the location of the production and during specific field recording trips.

  • Pre Production Sound Design - Some sounds may need to be created before production begins, to be played on set for actor's cues or to meet the Director's approval in time for Post Production to start.

We believe that every project can be enhanced with the early involvement of the Audio Post Production team. Getting your Audio Post Production team in early means that we can help with advising on your location choices, perhaps the rooms chosen are too reverberant, or too noisy?

From a budget perspective, this knowledge is invaluable for saving on ADR time and costs. We can also take a listen to your rushes to advise on possible ADR before your actors disappear into the wilderness!

The workflow for Post Sound remains a mystery to many Directors and Producers. Having the time to guide them through the delivery of media to us, makes everyone’s lives so much easier and leaves more time for creativity.

Check out these two articles for more on communicating with directors and producers…

  • How To Communicate Post-Production Sound With Directors - The post-production sound process can be confusing for newer directors, and often represents a gap in their knowledge when compared to other areas of production such as camera or lighting. For audio-post professionals, it is our job to guide them through the process and ensure a smooth and collaborative experience through solid communication, empathy and patience.

  • A Filmmaker’s Perspective On The Importance Of Audio Post - The article, has been written by director and long time collaborator of 344 Audio - Kaine Levy.

Audio Post Production Job Roles

While many audio post professionals cover multiple roles when completing a project, understanding the key differences between each of the different job roles is essential. This is especially important if you move higher up the food chain and are working on more large-scale productions, as work tends to become more specialised with individuals/small teams covering a specific area of the audio production. Knowing what each role entails is essential for smooth cooperation between teams and understanding how you fit into the bigger picture.

  • Dialogue Editor - Dialogue Editors take the Location Sound that is synced up by the picture editor, and work to ensure a constant flow of dialogue without clicks, pops, noise, distortion and discontinuities.

  • ADR Mixer - ADR Mixers record ADR (automated dialogue replacement) to replace unusable audio from the location. They liaise with the Director and Talent to get the best performance and believability out of the recordings.

  • Sound Designer - A Sound Designer is a multi-skilled sound professional who gets creatively and technically involved with making sounds to tell a story. On smaller budget projects, the Sound Designer may also be the Dialogue Editor, Sound Editor, Re-recording Mixer, Sound Supervisor and sometimes the Foley Artist.

  • Sound Effects Recordist - A Field Recordist who records custom sound effects for your project, often with high-end equipment.

  • Sound Effects Editor - A Sound Effects Editor takes recordings from sound libraries and places them in sync with the picture to help create a seamless flow of continuity and narrative.

  • Foley Artist - Foley Artists perform sounds that would be impractical to create using sound effects and sound design. Examples include footsteps, cloth movement and gun handling. They also add a layer of continuity to your actor’s performance.

  • Foley Mixer - Foley Mixers record the sounds that the Foley Artist creates, giving them feedback on the performance whilst listening for technical issues.

  • Foley Editor - Foley Editors edit the Foley Artist's work, to make it sync with the picture and to assure that it is suitable for mixing by the Re-recording Mixer.

  • Re-Recording Mixer/Dubbing Mixer - A Re-recording Mixer takes the audio tracks that the team have created, deciding which elements will remain (in line with the Director's notes) as well as their overall tonal balance, distance perception and technical needs for the final deliverables of the Sound Mix.

  • Sound Supervisor/Supervising Sound Editor - A head of department, who often helps with building the Sound Team and overseeing the collaboration with the Director and Producers to achieve the best Final Mix possible.

Session Preparation

The Supervising Sound Editor and Re-recording Mixer will start by building a DAW master template that is suitable for the given project. This will likely house more than enough audio tracks to cover the whole film’s dialogue, sound effects and foley. They will then begin importing the necessary files: Video File with guidance audio track (used for checking synchronisation between sound and picture and OMF/AAF files (used for delivery of the production tracks synced by the Picture Editor).

Filmmakers/Editors - How To Deliver Audio & Video Assets To Your Sound Designer

Step 1: The Prep - When editing your film, keep dialogue, sound effects and music on separate tracks so that the AAF/OMF file we describe in the following section is organised upon delivery. You should never delete alternative mic options from the dialogue tracks, as your sound team may be able to use these later. When editing, audio synchronisation is crucial. Once you have synchronised your dialogue, the video and audio regions should stay linked so avoid sound slipping out of sync in your editing software.

Step 2: Audio Assets - Upload all of the audio rushes (audio takes recorded on set) to a file sharing service like Google Drive, which will allow your sound team to stream selected files online and download if needed.

Complete the final locked edit of your project (this can be pre Colour Grading or Visual Effects). Completion of your final locked edit before audio delivery will ensure the most seamless workflow with your Audio Post Production Studio. Place all current dialogue tracks, ADR, voice-over, sound effects and music at their desired timecode position in your editing session.

Place a 1kHz sine wave, 1 frame in duration, 2 seconds before the video region starts. When the final mix is delivered by the Audio Post Production Studio, you can use the sync tone in your edit and match it with the one present in their mix to achieve perfect synchronisation. The video region should start at timecode 01:00:00.00 unless your distribution specifications say otherwise.

Navigate to your software’s AAF/OMF export window (as shown below), and select the following settings:

  • File Format: AAF / (OMF if under 2GB) with Embedded Audio (do not embed the video)

  • Audio File Format: WAV

  • Bit Depth: 24 Bit

  • Sample Rate: 48kHz

  • Audio Handles: Minimum of 240 frames

This file will allow the sound team to access all of your audio edits, volume keyframes and extend takes within clips (it is comparable to an XML file). The better organised it is before delivery, the happier your Audio Post Production Studio will be, and the more time they will have for creative tasks.

Step 3. Video Assets - Add a timecode indicator to your video, placed inside the visual ‘letterbox’ (or where it would be) at the bottom or top of the frame. The audio attached to your video file will need to match the AAF/OMF file, so retain all dialogue tracks, ADR, sound effects and music at their desired timecode position in your editing session.

Navigate to your software’s video export window, and select the following settings:

  • Video Format: MOV Video Codec: Avid DNxHD is the officially supported format by Pro Tools (H.264 if your Audio Post Production Studio are willing to convert the file)

  • Video Frame Rate: Matching that of your video master

  • Resolution: Up to 1920 x 1080

  • Key-frames every 12 frames, P and B frames: Disabled

  • Automatic Key-frames: Disabled

  • Audio: Linear PCM/WAV in Stereo L/R

Step 4. Online/Physical Delivery - Keep all of these assets on an online file sharing service with no deletion date, and avoid using zip/rar archives. This is to reduce the risk of download corruption or lack of access. Ensure that the Audio Post Production Studio has checked and approved your assets before the start date of Audio Post.

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Setting Up Your Session

In Audio Post Production, having a clear session template can be the difference between a well structured, efficient workflow, and a selection of tracks that is difficult to navigate.

Here is a breakdown of how to set up your session, and the different types of tracks to include:

  • Dump/Dialogue Tracks - The Dump tracks are for all of your imported OMF/AAF file data and any recordings / sound effects that won't be used in the Final Mix. They should be made inactive when not in use. The Dials/ADR tracks are for editing and mixing dialogue, voice-overs and automatic dialogue replacement (ADR).

  • Foley/Spot/Atmos Tracks - The Foley tracks are for editing and mixing recorded foley footsteps, cloth movements and prop sounds. The Spot tracks are for editing and mixing sound effects that are not present but are needed to fit on/off-screen cues, for example, gunshots, doors closing etc. The Atmos tracks are for editing and mixing atmospheric sound effects, for example, wind blowing, birds tweeting etc.

  • Design/Music Tracks - The Design tracks are for designing, editing and mixing audio material, for example, trailer impacts, monster vocalisations and sub rumbles etc. The stereo Music tracks are for editing and mixing mainly non-diegetic music. The mono Music tracks are for editing and mixing mainly diegetic music.

  • Auxiliary Inputs - These tracks are for balancing the levels, frequency content and dynamics between dialogue, sound effects and music in your mix. For example, routing all of your dialogue tracks out to Aux 8, lets you control the levels of the dialogue as a whole against the other elements of the mix. Aux tracks are also used for adding reverb and delay to your mix via buses.  

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Dialogue Editing

The Dialogue Editor will either take sections from the master template above or use his own smaller DAW template to edit the dialogues. They will be using the OMF/AAF files delivered by the Picture Editor which contain the raw Dialogue and Location Sound recordings correctly synced to the picture. Dialogue Editing involves trimming and extending clips, adding fades, copy and pasting, swapping outtakes, and rendering audio repair effects onto clips. Removing any inconsistent and discomforting sounds allows the Re-recording Mixer to perform the mix with smooth and clean dialogue tracks. The Dialogue Edit can make or break a mix, so it is crucial to ensure that this sounds great before the Producer and Director make final approvals.

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Sound Effects Editing/Sound Design

The Sound Effects/Design team is often the largest sub-department and has the most extensive workload on some projects. They will use a part of the larger master template, dragging, dropping, syncing, fading and checking audio files against the picture. They build layers of sound effects taken from personal or commercial libraries to create an immersive soundscape in line with the Directors notes.

These sounds come in multiple categories:

  • Spot Effects aka Cut Effects, Hard Effects - Spot Effects are intended to cover obvious sounds on screen such as doors, vehicles, fist punches etc. They may also be used to replace or enhance sounds captured on the production tracks that aren't suitable for the Final Mix. Spot Effects can be quite complex, a combination of intensive sound editing sessions and communicating with the Foley team are needed to get the best results. Action films tend to be heavier on Spot Effects, as they include more vehicles, gunshots and punches; all of which must be covered.

  • Background Effects aka Atmos, Ambiences - Background Effects are used to widen the stereo image of your film and surround the viewer in the mix. They are often long, consistent and looping sounds that can give the audience a different perception of what is on screen. For example, if a scene has howling resonant wind it may feel empty or scary, but if it has tweeting birds it may feel more peaceful. Background Effects can also hide issues in the production track and tend to sell the continuity between shots in your scenes and transitions. They can also be a way to hide issues in your production tracks. For example, if you have a generator rumble under your dialogue, you may be able to hide it with a refrigerator noise if the scene is within a house. They can be quite extensive on some projects. It is not uncommon to see 8 or more layers of ambient sound covering a scene simultaneously.

  • Design Effects aka Sound Design, Design - These elements cover unnatural/otherworldly sounds, musical sound design or audio that must be manipulated and heavily layered to get the desired result. Examples include monster growls, earthquakes, spaceships, trailer sound effects and drones.

  • Capturing Sounds - Capturing your own sounds is an essential part of the audio post-production process. No matter how many sound effects libraries there are to choose from, there will always come a point in a project where you can't find the sound you need and must either capture or create it. You will principally turn to either field recording or foley as your solution.

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Sourcing Sound Effects

Foley

Due to the nature of how most DAW systems work, any changes to the Picture Edit that take place after the Post Production Sound Team has started working will cause synchronisation issues. Anything from a single frame change to multiple scene cuts must be logged by the editor and delivered to the Sound Supervisor in the form of an Edit Decision List (EDL) and a new video file. It is best to avoid this as additional costs will be incurred, expensive software solutions will be needed, and the Sound Team may need to re-edit their tracklay (a combination of dialogue, sound effects, foley and music) manually.

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Mixing

Mixing? What the hell is mixing anyway? It’s a strange craft at the best of times; part science part creative art. Essentially though at its core, it’s balancing a multitude of sound elements in a cohesive way helping to tell the story and drive the drama of the project.

Delivery of the narrative is everything. Coming at the end of the post-production process it can also end up as the battleground for squeezed budgets, timescales and fixed delivery schedules.

The Final Mix will be performed by the Dubbing Mixer/Re-recording Mixer after all of the tracklay is completed and the Director has approved the work.

The Re-recording Mixer will use a combination of software tools to sculpt the mix, ensuring that dialogue is consistent, the foley is realistic, sound effects have an interesting surround field, the music blends well and there is a pleasant tonal balance overall.

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Acknowledgements

A special thanks must go to my team at 344 Audio for their help in creating the bulk of this audio post-production guide.

Thanks also to all the Pro Tools Expert audio post-production contributors.

We all hope that you have found this guide helpful. If so, all the hard work will have been worth it.

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