Does it make sense to extract both?

In a particular workflow, yes, it makes a lot of sense. If you are going to edit the audio, you extract WAV first, finish all the work on that, then save the final version you will distribute as MP3. That way there is only one link in your lossy compression chain. But there is no benefit in keeping two separate files just for listening, you only waste disk space.

Does WAV always sound better than MP3?

No. Because the audio inside the source MP4 has already been compressed with AAC, WAV cannot bring those losses back; what you get is a file that sounds practically identical to the source but is much larger. Under normal listening conditions it is extremely hard to hear a difference between WAV and an MP3 extracted at a high enough bitrate. WAV's advantage is not in the quality you hear but in the fact that it adds no further loss during subsequent operations.

Which is more suitable for transcription and speech recognition?

WAV is usually preferred, because most of these tools work more comfortably with a raw signal free of compression artefacts, and they convert audio to WAV in their own pipelines anyway. Giving them WAV directly removes that step. For recordings that contain speech only, choosing mono to reduce the file size is also perfectly reasonable and does not noticeably affect accuracy.

Does it make sense to archive a long recording as WAV?

Usually it is unnecessary. If your original video file is still there you can extract the audio again whenever you need it, so keeping a huge WAV in the archive most often has no point. Keeping the WAV is only valuable if the edits you made live in that file. If you want a lossless but compressed archive, a format such as FLAC takes up noticeably less space than WAV.

Should You Extract WAV or MP3 from MP4? Deciding by Purpose

The decision is not really technical, it is about purpose

The question "is WAV or MP3 better" has no single right answer, because the two were designed for completely different jobs. It is like comparing a hammer with a screwdriver. The right question is this: what are you going to do with this audio?

Even so, before you can decide you need some shared technical ground, because the most common misconception hides exactly there.

The one fact everybody needs to know

The audio track in your MP4 file is most likely compressed with AAC. AAC is a lossy format — it shrank the file by discarding the information the human ear is least likely to notice. The discarded information is permanently gone.

That means:

When you extract WAV, the audio is decoded into raw PCM data and stored without compression. No new loss is added in that step. But the information AAC threw away earlier does not come back either. The result: a file that sounds practically identical to the source, many times larger.

When you extract MP3, the audio is decoded to its raw form and recompressed with the MP3 encoder. That means a second round of discarding, so a small additional loss occurs. The result: a small file that sounds very close to the source.

So WAV does not add quality, it adds no loss. MP3 adds smallness, it adds a small loss. The whole comparison revolves around those two sentences.

Axis 1: File size

Here MP3 has an overwhelming advantage, and this is beyond dispute.

WAV applies no compression at all, so the file size depends directly on the duration of the audio, the sample rate, the bit depth and the number of channels. On a long recording the WAV output can come out even larger than the source video.

MP3, on the other hand, was designed precisely to bring that size down, and it does so very successfully. Storing on a phone, uploading to the cloud, sending to somebody — all of it is practical with MP3 and painful with WAV.

Winner: MP3, by a clear margin.

Axis 2: Compatibility and portability

MP3 is the common language of digital audio. Phones, car stereos, old MP3 players, browsers, messaging apps, presentation software — all of them open MP3 without trouble. When you send a file you do not have to wonder whether the other person will be able to open it.

WAV is in fact also very widely supported, and you will have no trouble on that front. The real problem is size: sending WAV files through messaging apps is usually impossible, they do not fit as an email attachment, and cloud uploads take a long time.

Winner: MP3.

Axis 3: Editing and processing

Here the table turns completely, and the difference is at least as pronounced as the previous ones.

Working on MP3 has a concrete problem: every save means a new round of lossy compression. You cut the audio and saved, then you cleaned up noise and saved again, then you corrected the levels and saved once more — at every step the encoder performs a new round of discarding. Those losses accumulate, and after a few steps they can become audible.

With WAV that accumulation never happens. You edit as much as you like and save as much as you like, and raw data is stored every time. Audio editing software also processes WAV directly with no decoding step; on large projects that makes a serious difference in speed.

The situation is similar with transcription and speech recognition tools: most of them work more comfortably with a raw signal free of compression artefacts, and they convert audio to WAV in their own pipelines anyway.

Winner: WAV, by a clear margin.

The decision table

Extract MP3 if:

You want the audio in order to listen to it — on the phone, in the car, in the background
You are going to send the file to somebody
You are archiving a podcast episode or a lecture to follow later
Your device space is limited
You are not going to do anything else with the audio

Extract WAV if:

You are going to edit, cut or join the audio
You are going to apply noise removal, level correction or effects
You are going to import it into an editing program or music software
You are going to feed it to a transcription or speech recognition tool
You are going to work on this audio in more than one step

Use both in sequence if: you are going to edit and then share. This is the most robust workflow: first take the raw audio with the MP4 to WAV extraction tool, finish all the editing on that, and at the very end save the version you will distribute as MP3 in a single pass. That way there is only one link in your lossy compression chain.

Two common mistakes

Mistake 1: "WAV has better quality, so let me make everything WAV." If the source is already AAC, WAV gives you no extra quality, only huge files. Storing audio you are only going to listen to as WAV is a waste of disk space.

Mistake 2: "MP3 is enough, I will edit in it too." For a single cut it may be no problem, but in multi-step work the losses accumulate. What is more, that accumulation cannot be undone; by the time you notice it you have to start over.

Legitimate ways to ease the size problem

If WAV is necessary but the size is a strain, there are two reasonable options. If you are only working on speech, choosing mono halves the file and does not noticeably affect transcription accuracy. If you want a lossless but smaller archive, a losslessly compressed format such as FLAC stores the same data as WAV in noticeably less space; however, some audio software does not work with it as smoothly as with WAV.

Deciding through concrete scenarios

Instead of abstract rules, let us look at situations you often run into; your own job probably resembles one of them.

You recorded a lecture or a conference to listen to. MP3, 128 kbps. Speech sits in a narrow frequency range, it stays fully intelligible at this setting, and the file fits comfortably on your phone. Extracting WAV brings you no benefit at all.

You are going to transcribe an interview. WAV, preferably mono. Transcription tools work more comfortably with a raw signal, and choosing mono halves the file without affecting accuracy. When the job is done you can delete the WAV, because what is valuable is the text that came out.

You are going to edit your podcast episode. Start with WAV, do all the cutting and cleaning on that, and save the final file you will publish as MP3 in a single pass. This reduces your lossy compression chain to a single link.

You are going to separate the music from a concert video and only listen to it. MP3, 256 kbps. Because the source is already AAC, WAV gives you no extra quality; a high-bitrate MP3 sounds practically identical and is far more useful.

You are going to use the music from the video in another project. WAV. You will be cutting, adjusting levels and probably applying effects; it matters that no new loss is added at each step.

As you can see, the distinction always ties itself in the same place: is the audio the final product, or the raw material?

In summary

The choice between WAV and MP3 is not a quality contest but a matter of purpose. WAV does not bring back the loss in the source, but it prevents further loss from being added after that point — which is why it is the right starting point if you are going to work on the audio. MP3, in exchange for a small additional loss, makes the file portable and practical; it is the right choice for listening and sharing. In short: WAV if you are going to work, MP3 if you are going to listen. If you are going to do both, use them in sequence and leave the compression to the very end.