Plenty of things worth listening to arrive as video: a recorded lecture, a webinar, a band rehearsal filmed on a phone, an interview you want to transcribe, a voice memo someone sent as a screen recording. As MP4 files they are large, need a screen and drain the battery. As MP3 they are a fraction of the size and play in the background on any phone, car stereo or podcast app.
This converter reads MP4 files, discards the picture and encodes the audio as MP3 at the bitrate you choose. Add one file or a whole folder's worth, press Convert, and download each MP3 or all of them in one ZIP. Everything runs locally in your browser.
What extracting audio from an MP4 actually does
An MP4 file is a container with separate streams inside it. In almost every MP4 from a phone, camera or video platform, the sound is an AAC stream sitting next to the H.264 or HEVC picture. Extracting it means reading only that audio stream, decoding it and encoding it again with the LAME MP3 encoder. The video stream is skipped entirely and never decoded, which is why this is far quicker than converting the video itself.
The result is an ordinary MP3 file of the same length as the soundtrack, named after the video. MP3 holds at most two channels, so a surround soundtrack is mixed down to stereo. The MP4 itself is left untouched on your device.
When MP4 to MP3 is the tool you need
Lectures, talks and webinars on the go
A one-hour talk as 1080p video might be several hundred megabytes. As a 128 kbps MP3 it is around 55 MB and can be played with the screen off during a commute or a run.
Preparing audio for transcription
Many transcription services and apps accept MP3 more readily than video and process it faster. Sending only the sound also keeps faces and screens out of a third-party system when you only need the words.
Keeping your own recordings as music or memos
Rehearsals, voice notes recorded with a camera app and family events filmed on a phone often matter mainly for their sound. An MP3 copy is easy to archive, tag and play in any music library.
Choosing a bitrate
The Bitrate menu offers 128, 192, 256 and 320 kbps at a constant rate, with 192 as the default. Each step trades size for fidelity: 128 kbps uses about 1 MB per minute and is fine for speech; 192 kbps, roughly 1.4 MB per minute, is a safe choice for music; 256 and 320 kbps use about 1.9 and 2.4 MB per minute and give the most headroom. Keep in mind that the source is already compressed. The AAC track inside a typical MP4 often runs at 96 to 256 kbps, and converting it to a higher MP3 bitrate cannot bring back detail that was never there; it only makes the file bigger.
The extraction is done by ffmpeg compiled to WebAssembly. It is downloaded once, about 31 MB, the first time you press Convert, and your browser keeps it for next time. It runs on a single thread, so a long video takes longer on a phone than on a laptop, but because only audio is processed it is usually much quicker than any video conversion. Each MP4 can be up to 500 MB, and above 200 MB some phones and browsers may run short of memory.
Bu araç nasıl kullanılır
- Drop one or more MP4 files on the box above, or click it to browse.
- Open the Bitrate menu and pick 128, 192, 256 or 320 kbps.
- Press Convert. On first use the converter downloads before the audio is extracted.
- Download each MP3, or press Download all (.zip) to save them in one archive.
Limitations
- Only MP4 files are accepted here. For audio files such as M4A, WAV or FLAC, use Convert Audio instead.
- The whole soundtrack is converted. To keep only part of it, trim the MP3 afterwards with Trim Audio.
- An MP4 without an audio track, such as some screen recordings, cannot produce an MP3 and shows an error.
- If a video carries several audio tracks, for example two languages, only one of them is extracted.
- Files over 500 MB are not accepted.