Many location sound recorders can write several audio channels into a single WAV file, known as a PolyWAV. Depending on the recording, those channels may carry a boom microphone, lavalier microphones, a mix track, additional microphones or other isolated channels.
In some workflows, it is useful or even necessary to extract these channels as separate mono WAV files. This article explains what that operation does and what to keep in mind before doing it.
WHAT IS A POLYWAV FILE?
A PolyWAV is a multichannel WAV file: several audio channels are stored together inside one WAV container. The channels share the same length and start time, so they stay in sync as a single file.
The audio itself can be identical in both cases. What changes is how the channels are packaged and how easily each one can be handled on its own.
WHY SPLIT A POLYWAV INTO MONO FILES?
Splitting is not always necessary. Many professional editing and post-production applications work directly with multichannel PolyWAV files. Separate mono files can still be useful when you need to:
- access individual microphone channels on their own;
- work with software or workflows that handle mono files more conveniently;
- isolate specific channels from the rest of the recording;
- prepare files for another editing or post-production workflow;
- inspect or organize individual tracks.
WHAT HAPPENS WHEN A POLYWAV IS SPLIT?
Splitting separates each channel of the PolyWAV into its own file. The channels are not mixed together: each output file contains exactly one channel from the source.
A six-channel PolyWAV therefore becomes six mono WAV files, one per channel.
CHANNEL ORDER MATTERS
Before splitting a multichannel recording, it helps to know what each channel represents. In production sound, channels may correspond to different microphones, isolated tracks or a mix track.
There is no universal channel assignment. The layout depends on the original recording and on how the recorder was configured. When in doubt, inspect the file and its metadata, or check the sound report, before splitting. For more on how recording information is structured, see sound metadata.
SPLIT A POLYWAV IN YOUR BROWSER
If you only need to extract the individual channels from a PolyWAV file, Audio Tool Kit provides a dedicated browser-based PolyWAV splitter designed for this operation: Split a PolyWAV with Audio Tool Kit.
BEFORE YOU SPLIT THE FILE
POLYWAV OR MONO WAV?
Neither format is universally better. A PolyWAV is convenient for keeping multiple synchronized channels together in one file. Individual mono WAV files are useful when channels need to be accessed, organized or processed separately.
The right choice depends on the production and post-production workflow the files are going into.