How To Use The Pro Tools Ultimate Field Recorder Workflow
In our recent podcast on all things Dialog, we discussed that the Pro Tools Field Recorder Workflow, introduced in Pro Tools 7, is still very much a thing in modern audio post-production workflows.
Using embedded metadata and timecode from the BWAV files, the field recorder workflow in Pro Tools is able to rebuild the multi-channel recordings, expanding the various microphone channels to new tracks in Pro Tools and matching the edits made by the video editor.
This involves designating a track as a field recorder guide track and then using Field Recorder Match Criteria to specify to Pro Tools what constitutes a match to the edited rough mix.
A Glossary Of Terminology For Field Recorder Workflow
Before we go any further let’s acquaint ourselves with the terminology used...
Timecode - There are four types of timecode, depending on your production:
Keycode - Each frame of film stock is embedded during manufacturing with a unique identifying timecode position known as keycode.
SMPTE Timecode - Also known as LTC or linear timecode. The generating clock of this timecode can be based on the time of day or can be set to ascend beginning from a certain starting time of day.
Minutes:Seconds - Timecode based on minutes and seconds.
Wild - No timecode. Most consumer digital video recorders do not have the ability to generate timecode.
Production Sound Mixer - The production sound mixer uses a field recorder to record multichannel audio during a shoot, and later delivers those source files to one or more parties:
Telecine Operator (only when the project has been shot on film). telecine is the tool that converts the film into video footage.
Digital Image Technician (DIT) - Although the DIT is officially part of the camera teams, will of course also be handling media management, storage, and backup.
Video Editor - On smaller projects, it may well be the video editor, or more likely their assistant, will be responsible for the ingest of the rushes from the location.
Pro Tools Editor -Alternatively the Pro Tools Editor, which in this case is likely to be an assistant in the sound post-production team can be responsible for the ingesting of the raw audio rushes.
Shootlist - The shootlist is a document in which the camera assistant records each scene and take, relative to its keycode value on the film stock. It is later used by the telecine operator to synchronise the audio and video together.
Sound Log - The sound log is a document in which the production sound mixer records each scene and take relative to its beginning timecode position.
Slate Operator and Clapboard Information - The slate operator holds and labels the slate (also known as a clapboard) for each new scene and take. At the start of each take, the slate operator claps the slate, which simultaneously captures the following information:
The scene, take, and timecode information is captured visually on film.
The sound of the slate clapping is captured by the field recorder, which should be using the same timecode as displayed on the slate.
If the project is being shot on film, the telecine operator uses all of this information to synchronise the film stock to the recorded audio in order to create the telecine video files.
FLEx File - The FLEx file is a text file generated during a telecine session that relates film keycode, field recorder timecode, and telecine videotape timecode. When the telecine video files are ingested into the video editing application, the information in the FLEx file is used to assign the original (location) timecode to the resulting audio and video source files.
Metadata is used to describe the following:
Information embedded in a media file. This may include scene, take, sample rate, bit depth, external clip names, the name of the media( which used to be tape) from which the media file was captured, and even timecode values.
Information embedded in Pro Tools sessions or other sequences, including what files are used, where they appear in a timeline, and automation.
For AAF or OMF sequences, information about automation or clip-based gain.
Digital Field Recorders - A field recorder, also known as a hard disk location audio recorder, is a device used by a production sound mixer during a film or video shoot to make a multichannel recording of multiple microphone inputs recorded simultaneously.
Depending on the capabilities and settings of a field recorder, multichannel recordings can include one or more tracks (up to 32) and are saved as monophonic or polyphonic audio files onto a hard drive, DVD-RAM, or cards.
Multichannel recordings made by a field recorder should be encoded with start and end timestamps representing SMPTE timecode or linear timecode (also known as LTC). Most field recorders also allow the manual entry of additional types of metadata, including Channel Name/Number, Scene, Take, Circled Take, User Bits, and more.
Pro Tools can import monophonic and polyphonic files and certain types of metadata entered on field recorders.
Production Sound Mix - For each multichannel recording made by a field recorder, the production sound mixer may designate a production sound mix comprising either a representative channel or a mixdown of other selected channels in the recording.
The production sound mix is intended to function as a general reference of all audio recorded within an individual multichannel recording and is typically used by the video editor when assembling a sequence.
Broadcast WAV Files (BWF) - A WAV file containing a BEXT chunk is known as a Broadcast WAV file (or BWF) while still maintaining a .WAV file extension. Broadcast WAV files can contain both BEXT and iXML chunks, or a BEXT chunk by itself.
BEXT and iXML Chunks - These are sets of metadata found within a Broadcast WAV file.
The following limitations apply to the handling of imported metadata from field recorders.
The BEXT specification as described here adds some features that conform to standards used by video editing applications and Pro Tools, specifically, description metadata is interpreted differently.
When you import multiple files in which the same metadata are populated with different values, Pro Tools imports the value that is first present based on the following order…
Avid OMF-wrapped media or MXF media
Any iXML chunk metadata in a BWF
Any BEXT chunk metadata in a BWF
Supported Field Recorder Audio Files and Metadata - Pro Tools supports the following audio files recorded by field recorders:
OMF wrapped media
AAF wrapped media
MXF
Broadcast WAV (BWF) files with the following metadata:
Both BEXT and iXML chunks
BEXT metadata but no iXML metadata
Example Workflow: Working with a Guide Track
For live concert videos, the video is usually captured separately from the audio. The video editor uses a guide audio track that is edited along with the video in their video editing software. The edited guide track is then returned to Pro Tools, and then the field recorder workflow is used to expand the conformed original source tracks for mixing and mastering.
Multitrack audio is recorded with timecode. A mono or stereo mix is provided as a guide track for the video editor.
The picture and audio guide tracks are edited in a video editing application (such as Avid Media Composer).
The edited audio guide tracks are exported from the video editor as an AAF (or OMF) sequence, including handles of at least 2 frames.
The AAF (or OMF) sequence is imported into Pro Tools as a new session.
The original source audio files and unedited guide track are also imported into the session.
The original unedited guide track is relinked to the session. To relink the original unedited guide track do the following…
Open a Workspace browser. Select your session in the Locations column, then open or expand the Session Audio Files folder.
Right-click the edited guide track audio file in the browser and choose Relink Selected Items.
In the upper pane of the Relink window, navigate to the original unedited guide track audio file that was recorded in Pro Tools.
If the original unedited file is not available, you can relink to any of the source audio files as long as they have the same start and end times as the guide track.
In the Select Files To Relink pane, select the edited guide track file.
Drag the original unedited guide track audio file into the Candidates pane. If a dialog appears stating that one or more files are shorter than the media file you are trying to relink, click Yes to select it for relinking anyway.
Check the box to the left of the file in the Candidates pane so that the Link icon appears.
Click Commit Links at the top of the Relink window and then close the Relink window.
Right-click the name of the guide track and select Expand Channels to New Tracks > By Timecode Only. The original source tracks expand to new tracks with edits and fades, that match the guide track.
To help demonstrate this, in this free video tutorial, Paul Maunder show how the field recorder workflow, which is only available in Pro Tools Ultimate, works in practice….