When to Export WAV vs. MP3: Understanding Audio File Formats

When to Export WAV vs. MP3: Understanding Audio File Formats

This is a question I get frequently from my students, and it's a perfectly reasonable one! Deciding between WAV and MP3 can seem technical, but it boils down to a simple principle.

Here's my rule of thumb for determining which format is appropriate:

Will the recipient of the audio need to make changes to the audio?

If the answer is "yes," then – in general – you should provide them with a WAV file. Of course, there will always be exceptions, but this is a great starting point for maintaining audio quality throughout your workflow.

Understanding the Difference: Lossless vs. Lossy

It's helpful to understand the core difference between these two common formats. A quick search will provide more detailed information, but for the sake of simplicity, here's an overview:

  • WAV format: This is what is referred to as a "lossless" format. Think of it like a perfect, uncompressed digital copy of your audio. Rendering your audio to WAV results in no loss of original data. This means the file will be larger, but it retains the highest possible audio quality.
  • MP3 format: This is a "lossy" format. When you render audio to MP3, the encoding process "throws away" certain data it determines isn't essential to perceived sound for the sake of creating a much smaller file. This process is generally optimized to minimize audible quality loss, but some data and therefore some quality is permanently discarded.

The logic behind our rule of thumb is simple: we want to maintain the highest degree of quality throughout the entire production process. You should save the "lossy" MP3 conversion as the absolute final step, only when the audio is complete and ready for its end-use or distribution.

Common Audiobook Production Scenarios & Recommended Formats:

Here are some common audiobook production scenarios and the recommended file format for each:

  • Deliver Audio to Proofer:
    • Rule of Thumb: Does the proofer need to make changes? The answer is generally "no." The proofer will listen to the audio and review the manuscript, noting any issues encountered (like flubs, mouth noise, or pacing issues).
    • Recommended Format: MP3s. These are smaller files, making them easier to send and review quickly.
  • First 15 Minutes / Sample (for Rights Holder Review):
    • Rule of Thumb: The rights holder is listening for performance, voice fit, and overall quality, but they aren't directly editing the audio at this stage.
    • Recommended Format: MP3s. Again, smaller files are more convenient for review.
  • Deliver Audio to Editor / Mixer / Mastering Engineer:
    • Rule of Thumb: The editor will make significant changes to the audio, including removing noise, trimming for narrative flow, compiling chapters, and performing overall mixing and mastering.
    • Recommended Format: WAV files (typically 16-bit, 44.1 kHz). This is crucial. Always provide the highest quality, uncompressed files to anyone who will be working on your audio.
  • Export Before Processing (e.g., before batch processing in iZotope RX):
    • Rule of Thumb: If you are performing a specific processing step (like running a large section of audio through a cleanup suite like iZotope RX), and it's an intermediary step, you are inherently "changing the audio."
    • Recommended Format: WAV format. You want to ensure no quality is lost by converting to a "lossy" format before cleanup and final processing.
  • Upload Final Files to ACX (or other distributors like Findaway Voices):
    • Rule of Thumb: This is a primary exception to the "always use WAV if changes are made" rule for your own workflow. ACX (and many other distributors) requires that the final version of the audio be delivered as MP3s. They will perform some degree of final processing or re-encoding on the audio to prepare it for retail distribution.
    • Recommended Format: MP3 (usually 192kbps or higher constant bit rate - CBR). Always check the specific requirements of the platform you're uploading to, but MP3 is standard for final delivery to these platforms.

By following this simple guideline, you'll ensure that your audio retains its integrity and highest possible quality throughout the entire production workflow, only converting to a smaller, "lossy" format when it's truly time for final delivery or casual review.