Question 1

Will converting MP4 to MP3 lose quality?

Accepted Answer

A little, and it is worth knowing why rather than being reassured. The audio inside an MP4 is almost always AAC, which is already a compressed format: part of the original recording was discarded when the video was made. Writing an MP3 compresses what is left a second time, by different rules, so a little more goes. At 192 kbps from a normal source almost nobody hears the difference on normal speakers. Where it does show is on a recording that was already thin, or on a file that gets converted again later. If you want none of that at all, pick 'Copy it out untouched' and the original track comes out exactly as it went in.

Question 2

Which bitrate should I choose for MP4 to MP3?

Accepted Answer

128 kbps for a voice, 192 kbps for music and general listening, and 320 kbps only when the source is genuinely better than that, which it usually is not. A phone recording, a video call and most web video carry between 96 and 128 kbps, and encoding one of those at 320 kbps gives you a file two and a half times the size that sounds identical, because the detail 320 kbps exists to preserve was thrown away before you opened the file. The source's own number is the ceiling, and it is on screen next to every file. Leaving the setting on 'Match the source' picks the nearest standard step at or above each file's own bitrate, which is why the page starts there.

Question 3

How do I convert MP4 to M4A without re-encoding it?

Accepted Answer

Pick 'Copy it out untouched' under the output format. The audio track is lifted out of the container exactly as it is, byte for byte, with nothing decoded and nothing encoded in between, so it takes about as long as reading the file and loses nothing at all. What comes out is an .m4a, because an AAC track on its own is what an .m4a holds; writing those same bytes into a file named .mp3 would produce something most players refuse to open. The Music app, VLC, Windows Media Player, Android phones and every iPhone play .m4a. Choose MP3 instead only when the destination will not, and that is usually a car stereo or an older MP3 player.

Question 4

Can I convert MP4 to WAV instead?

Accepted Answer

Yes. Pick WAV under the output format and everything already in the list is rewritten. WAV is uncompressed, so no encoder touches the audio: what came out of the decoder is what lands in the file. That is what transcription services and audio editors ask for, and the right choice when the file is going somewhere that will process it rather than play it. The cost is size. A minute of 44.1 kHz stereo comes to about 10 MB, so an hour-long recording is roughly 600 MB. Switching the channels to mono halves that, with no audible difference on a recorded voice.

Question 5

Can I get FLAC or OGG out of this?

Accepted Answer

Not at the moment, because no browser can write either one. They all play FLAC and Ogg Vorbis; none of them carries an encoder for them, so there is nothing here to call. The page checks every time it loads and the options appear on their own the day that changes. What people are usually after is covered anyway: if the point is losing nothing, copying the track out untouched beats FLAC, since it does not re-encode at all, and if the point is a small file, MP3 plays everywhere and Opus is smaller still.

Question 6

Is there a limit on file size or length?

Accepted Answer

No. Nothing caps how large a file is, how long a recording runs, or how many are in the list, because the work happens on your own processor and costs nobody anything. The video is read in pieces off your disk rather than loaded whole, so a multi-gigabyte recording never has to fit in memory at once. What a long one costs is time: encoding runs several times faster than real time, so a ninety-minute lecture at 192 kbps takes a few minutes rather than ninety, with a progress bar for the batch and a second one inside each file. Copying the track out untouched is the fast path, because nothing is decoded on the way.

Question 7

Can I convert a whole folder of recordings at once?

Accepted Answer

Yes. Press 'Choose a folder' and pick the folder itself rather than the files inside it, which is what a lecture series or a set of interviews actually is once it is sitting on your disk. Everything in it that holds audio joins the queue, and the slide decks, notes and thumbnails are left where they are. Several convert at the same time, across as many of your processor's cores as it can spare, and you can take the lot as one ZIP. Two recordings with the same name from different folders each get a name of their own.

Question 8

Can I extract audio from a MOV, MKV or AVI file?

Accepted Answer

Yes, on this same page with the same settings. Converting MOV to MP3 is the same operation MP4 to MP3 is: MP4, MOV, MKV, WebM and AVI are containers, and the audio track sits inside each of them the same way. A MOV off an iPhone or a screen recording, an MKV from a download, a WebM from a browser capture and an AVI from an old camera all read alike. Audio files go through as well, for when what you have is an M4A that will not play somewhere rather than a video.

Question 9

Do my files get uploaded anywhere?

Accepted Answer

No, and there is no server here that could receive one. Your video is read, decoded and written back out by your own browser on your own machine. If you would rather check than take that on trust, open the network tab and convert something: nothing goes out. That is the part that matters when the recording is an interview, a client call or a session you were asked to keep private, which is a large share of what gets dropped on a page like this. Clear the list afterwards and nothing is left.

Question 10

Can I convert a YouTube video to MP3 here?

Accepted Answer

No. This converts a file you already have on your device, and it has no way to fetch anything from the internet, because there is no server behind it to do the fetching. If the video is one you uploaded yourself, YouTube Studio hands the original file back, and that file works here.

Question 11

How do I convert MP4 to MP3 on a Mac?

Accepted Answer

For one file, macOS can do it without a browser at all. Set the Music app's import format to MP3 first, under Settings, Files, Import Settings, then open the video in Music and use File, Convert, Create MP3 Version. For a single file that is genuinely quicker than any website. Come back here when you have a folder rather than a file, when you want to choose the bitrate rather than accept whatever Music is set to, when you want the track copied out without re-encoding, or when Music refuses the file. Windows has no equivalent built in, which is why the question comes up far more often there.

Question 12

How do I convert MP4 to MP3 in VLC?

Accepted Answer

VLC does it, and if it is already on your machine that is a fair answer: Media, then Convert / Save, add the file, Convert / Save again, choose 'Audio - MP3' as the profile, pick where the file goes, Start. The bitrate lives inside the profile, so changing it means editing the profile first. Where VLC is genuinely better is a file this page cannot read at all, because it carries its own decoders for formats browsers were never given.

MP4 to MP3 Converter

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