6 min read
AAC vs MP3 vs WAV: which format belongs at which stage of your film
Three formats, three jobs. Problems start when a review format ends up in the mix session.
AAC, MP3 and WAV are not competing for the same job. One is a working master, two are delivery wrappers, and the difference matters most when a file crosses from one stage of production to another.
WAV: the working format
Uncompressed PCM, no generation loss, carries BWF metadata such as timecode, scene, take and track names. Big files, universal support. Everything that is going to be edited, mixed or archived should be WAV.
AAC: the modern lossy default
AAC is what sits inside almost every MP4 and MOV delivered for the web, and what most cameras write for their scratch audio. At the same bitrate it outperforms MP3, particularly below 128 kbps and on high frequency content. It also supports multichannel, which MP3 handles poorly.
MP3: still everywhere, still older
MP3 survives on compatibility rather than merit. For a stereo review copy at 192 kbps or more, nobody will complain. For anything else, AAC does the same job smaller, and WAV does the real job properly.
What conversion actually costs
- WAV to AAC or MP3: lossy, discards audio permanently, strips BWF metadata.
- MP3 to WAV: lossless as a container change, but the discarded audio does not come back.
- AAC to MP3: transcoding one lossy format into another, which stacks two sets of artefacts. Avoid it.
- WAV to WAV at a different sample rate: a real conversion, so use good resampling rather than a rename.
The practical rule on a shoot
Keep every master as WAV. Generate AAC or MP3 only at the end of a chain, for a specific viewer or platform. When you receive a lossy file and need it in a session, convert it to WAV so the DAW is not decoding on every playback, but do not expect the conversion to improve anything.
You can do all of this here: extract PCM from an MP4, convert WAV to MP3 for a review link, or take an MP3 into WAV for a session, entirely in the browser with nothing uploaded.