If you are extracting audio from a video simply to listen to it, MP3 is the right answer and you can stop reading. But a lot of extracted audio has work ahead of it: a recorded interview that needs noise reduction, a talk that needs levelling, several clips that need cutting together, or a recording heading into a transcription tool. In those cases the format you extract to matters more than it first appears.
The problem with editing lossy audio
Lossy compression discards data the encoder judges you will not miss. That judgement is made about the audio as it stands at that moment — and editing changes it.
Apply noise reduction to an MP3 and you are processing audio that has already had detail removed, so the algorithm has less to work with and artefacts get amplified along with the signal. Raise a quiet section and you raise compression artefacts with it. Then, when you export, the whole thing is encoded lossily again — a second generation of loss on top of the first, applied to material the first pass never anticipated.
Each round of this compounds. It is the audio equivalent of repeatedly saving a JPEG: fine once, visibly degraded after several passes.
Extract to WAV instead
Converting to WAV decodes the video's audio to uncompressed 16-bit PCM and stops there. No second lossy pass. Every edit operates on the full decoded signal, every save is exact, and you encode to MP3 exactly once, at the end, when the audio is finished.
WAV is also simply what audio software expects. Audacity, Reaper, Audition, Logic, Pro Tools, Premiere and every transcription engine take it natively with no conversion prompt and no codec question.
The cost is size — roughly 10 MB per minute of stereo, so a one-hour interview is about 600 MB. That is a working-storage problem, not a permanent one: the WAV is scratch, the exported MP3 is the deliverable.
A clean workflow
- Extract to WAV. Send the video through MP4 to WAV. Batch a whole shoot or a whole course at once.
- Edit in WAV throughout. Trim, denoise, level, compress, splice. Save intermediate versions as WAV — they cost disk space but no quality.
- Export once. When the audio is final, encode to MP3 at 192 kbps for music-bearing material or 96 kbps for speech. Now the single lossy pass is applied to finished audio rather than a work in progress.
- Delete the WAVs once you are confident, or archive them somewhere cheap if the material is irreplaceable.
Transcription is the clearest case
Speech-to-text engines are unusually sensitive to compression artefacts, particularly on quiet speakers, crosstalk and accented speech. Most of them accept WAV natively and transcode anything else internally first — so handing them an MP3 means they decode a lossy file and work from that, while handing them a WAV skips a step and gives them more to work with.
If you are transcribing hours of interviews or lectures, extracting to WAV is the single easiest accuracy improvement available. It costs nothing but disk space.
When MP3 straight out is fine
Plenty of the time, honestly. If the plan is to listen on a commute, load a podcast onto a phone, or archive a talk you attended, extracting directly to MP3 is entirely sensible — one lossy pass on already-lossy source audio is inaudible at 192 kbps, and the file is a fiftieth of the size.
The rule of thumb: if the next step is listening, extract to MP3. If the next step is processing, extract to WAV.
A middle option
There is a third path worth knowing about. The audio in an MP4 is almost always AAC, and MP4 to M4A keeps it in that same codec family rather than translating it across to MP3. It is still lossy, but it is a gentler re-encode than a cross-codec one, and the file is smaller than the MP3 equivalent at the same perceived quality.
For light editing where WAV feels excessive — trimming the start and end of a recording, say, with no processing in between — M4A is a reasonable compromise. For anything involving actual signal processing, WAV is still the right call.
In short
Extracted audio that is going to be edited should be extracted losslessly. MP4 to WAV takes the same amount of time as extracting to MP3 and costs only disk space, and it means the one lossy encode in the whole chain happens at the end, to finished audio. The bitrate guide covers what to export at, the step-by-step guide covers the extraction itself, and the batch guide covers doing it across a whole project.