Preparing Modern Movie Digital Audio Files for Archive

Preparing Modern Movie Digital Audio Files for Archive

On this page

  1. Executive Summary
  2. Purpose
  3. Elements to Archive
  4. Audio Configurations
  5. General Notes and Preparation for Archiving

Executive Summary

It is very important to treat movie digital audio files correctly all through the process of capture, editing, mixing, mastering and distribution. It is then critical that these be organized for archiving in a manner that will be straightforward and easily usable in the future. This document details how to organize movie audio files for archive. The details of the actual media archiving and recommended procedures are left to a second document.

Elements to Archive presents a comprehensive list of audio elements to archive, from master elements to original source elements, as well as audio dubbed into local languages. Each element has a link to a page that depicts the audio configurations and file types to be archived for that element, with detailed information on organizing and formatting each audio element in preparation for final data archiving.

Audio Configurations presents a snapshot table of audio elements with their corresponding audio configurations that should be archived.

General Notes and Preparation for Archiving presents overall specifications and recommendations for the preparation of audio for archive, including a short summary of technical metadata to capture.

This recommended practice is intended to serve as an “uber guide” to movie audio archiving, based on what is created for today’s tentpole titles. Lower budget productions may not create all of these audio elements, but should still organize and archive what is created in a similar manner. The recommendations presented here should serve as a template that can be referenced by any movie studio or facility, ensuring that movie soundtracks are properly archived and available in the future.

Purpose

Audio production and post-production are entirely digital in today’s world, from the on-camera sound recordings through to the final audio that comes off the mixing stage. The entire workflow is dependent on the interoperability of the audio files that are generated in every part of the process. As these files are often shared over networks and common storage, no physical media is generated anywhere during the process (as was the case with analog production). Digital files by nature are ephemeral and only exist as bits on a storage device or in RAM. They can easily be mishandled, lost or erased. Tracking, managing, formatting, organizing, and naming of the files is a full-time job during the creation process, necessitating systematic, delineated procedures. Once the mixing is done and the project is complete, the audio should be archived in an organized and robust way that allows for reliable retrieval and future use. This presents its own unique set of challenges.

This document provides a recommended practice for preparing digital audio for archiving. It describes the audio elements that should be archived, with guidance for formatting and organization to ensure a consistent final turnover to the archive team.

Elements to Archive

Below is a list of audio elements that should be archived. Each links to detail on what should be archived for that element, pertinent notes about the element, and recommendations for its formatting and preparation.

Original Version (OV)

Master Elements

Ancillary Elements

Final Mix Source Materials

Production

Dubbed

Master Dubbed Elements

Script & Paperwork

Audio Configurations

Master and ancillary elements are archived in the configurations below. These differ by element — they are not uniform.

ElementContextImmersive7.15.1Two-Track
PrintmastersTheatrical●●●
Nearfield●●●●
StemsTheatrical●●●
Nearfield●●●
Music and Effects (M & E)Theatrical●●●
Nearfield●●●●
M & E StemsTheatrical●●●
Nearfield●●●
Fully-Filled Effects StemTheatrical●●●
Nearfield●●●
Dubbed PrintmastersTheatrical●●●
Nearfield●●●●
Dubbed Dialogue StemsTheatrical●●●
Nearfield●●●

A dot means the configuration is normally made for that element; a blank means it is not. Any configuration created on the mix stage should be archived. Stems and Dubbed Dialogue Stems, nearfield, additionally include the stem that made the two-track printmaster. Immersive Dubbed Dialogue Stems are created only where an immersive Dubbed Printmaster is.

What immersive is delivered as

ElementSessionADMIAB
Printmasters●●●
Stems●●
Music and Effects (M & E)●●
M & E Stems●●
Fully-Filled Effects Stem●●
Dubbed Printmasters●●●
Dubbed Dialogue Stems●●

Immersive delivery does not vary between theatrical and nearfield.

Predubs/Premixes, Temp Dubs, Mix Sessions and the editorial and production elements vary by project; their configurations are documented on their own pages.

General Notes and Preparation for Archiving

General Notes on Archive Deliverables

  • For each Master audio element, there should be a DAW session in the project folder that contains the session file and all audio files that the session references, and is thus self-contained.
  • A checksum (e.g. MD5) should be included in the project folder that indicates the collective sum of the files in the folder.
  • Each Master audio element should also have a READ ME in its project folder that acts as a table of contents of what is in the folder, plus stating any unique information pertaining to the element.
  • Input/Output (I/O) configuration files should be delivered for every workstation session in the session folder. An example file type is .pio. This will vary by workstation type. These are generally created from the I/O setup page by exporting.
  • All immersive sessions must have a renderer setup file. This should include the renderer type and version as well as specifics on the renderer setup. These are generally created by exporting from the renderer used.
  • All Master audio elements must be conformed to the final picture version.
  • Picture references at the frame rate of conform must be supplied. Both reels and long form picture should be supplied if audio is partitioned both ways.
  • File naming is extremely important and should be done in a consistent manner, following an agreed file naming schema that is well-documented and available as a Rosetta Stone for future parsing of the archived files. One such schema is posted (Audio Deliverables Naming).
  • The file naming “Rosetta Stone” used (procedure and any associated material) should be part of the archive for each title. Years down the road, links will not work. Archiving the Rosetta Stone with the archive ensures that the file names can be decoded and used many years hence.

Specifications

  • Reverbs should be recorded into the OV printmasters, stems and M&E, as well as dubbed printmasters and Dialogue stems.
  • Audio files must be Broadcast Wave (.wav).
  • Sample rates and frame rates should reflect those used to natively create the elements. No conversions should be done prior to archiving.
  • Sample rate should be 48.00 kHz or 96.00 kHz. No fractional sample rates should be used.
  • Frame rates are generally 24.00 for theatrical elements and 23.976 or 24.00 for nearfield elements. However, if the theatrical elements were mixed natively in 23.976, they should be archived as such.

Formatting

  • Partitioning can be in reels or long form.
  • If the partitioning is in reels, it is recommended that all reels be in the same session.
  • The file start for each reel should be at even timecode hours, hour = reel number. For example, reel 3’s files should start at 03:00:00:00.
  • If the partitioning is in reels, there should be a standard leader in front of program, typically 8 seconds long. For example, reel 3 would start at 03:00:00:00 with the leader, and the program would start at 03:00:08:01
  • If the partitioning is long form, the file and picture start should be 30 seconds ahead of program. Program should start on the even hour. For example, file start at 00:59:30, and program start at 01:00:00:00
  • Audio file start and picture file start should be the same with no offset required for them to run in sync.
  • Both head and tail sync pops should be on reference picture and all audio elements.

Validation and Handoff

  • Data validation must be performed via checksum. Checksums must be created and supplied by the file creators to the archive team.
  • A checksum (e.g. MD5) must be generated that indicates the collective sum of the files in a master session folder and put in that folder. For example, the 5.1 stems folder should have a checksum that represents all of the stem audio files and the workstation session plus any other files in the folder per the general delivery specs.
  • Each audio file should have a checksum generated and placed in the broadcast wave header that represents the entire file, including the header with the checksum.
  • Checksum example types:
    • MD5 (most commonly used as of this writing)
    • xxHash
    • SHA-1
    • SHA-256