MP4 to M4A Converter

Pull the AAC soundtrack out of an MP4 as M4A without re-encoding: identical audio in seconds, even from huge files. Runs in your browser, no upload.

Runs in your browser

Browser-only · packet copy, no re-encoding · exact length kept · non-AAC videos get their own original format.

MP4 → M4A Open Video to MP3

Nothing is re-encoded: the M4A holds the video's own AAC packets, byte for byte.

Drop files here or click to browse

MP4 · MOV · M4V · MKV · WebM · TS · Files never leave your device.

Output

MP4 → M4A

Lossless: the sound packets are copied without re-encoding, as .m4a, .ogg, .flac, .wav or .mp3 depending on the codec. Write tags Title, artist and date from the video; the file name becomes the title if there isn't one.

Files

Add video files to start.

Files are read on this device and never uploaded.

What "without re-encoding" means

An AAC sound track is a sequence of small compressed packets, each about 21 ms long at 48 kHz. Extracting without re-encoding means those packets are copied unchanged into a new M4A file; nothing is decoded and compressed again, so not a single bit of the sound differs from what is inside the video.

Converters that "convert MP4 to M4A" by re-encoding AAC at 128 or 256 kbps lose a little quality each time and change the file's bitrate. Here the bitrate, sample rate and channels are always the video's own.

Why it finishes in seconds

Copying packets needs no decoding, only reading. In tests, a 90-minute MP4 gave its 87 MB M4A in 6 to 14 seconds, and a 2.08 GB MOV gave its sound in under 3 seconds, including on Firefox. The picture data is skipped, not read into memory.

Phones work just as well, because memory use is about the size of the sound itself.

Proof that the audio is identical

The tool's tests compare a SHA-256 hash of every sound packet in the video with the same packets in the M4A; they match exactly for MP4, MOV, MKV and MPEG-TS sources (TS only drops the 7-byte ADTS frame headers that M4A doesn't use). For MP4, MOV and MKV sources the start delay of AAC (1,024 samples) is carried over in the M4A's edit list, so the file plays exactly as long as the video's sound: 10.000 seconds stays 480,000 samples at 48 kHz.

Your own check: the result shows the same bitrate as the source, and the badge "No re-encoding" appears only when the packet copy succeeded.

Where M4A plays, and ringtones

M4A (AAC in an MP4 audio file) plays on iPhone and iPad, Android, Windows 10 and 11, macOS, Chromebooks, VLC and most car systems from the last decade, and imports into Apple Music, iTunes and most editors.

For an iPhone ringtone, cut a section of up to 30 seconds with "Cut a section", rename the .m4a to .m4r and add it through Finder or iTunes on a computer.

Videos whose sound is not AAC

M4A can only hold AAC (or Apple Lossless) without re-encoding. A WebM or MKV with Opus sound gives the original as .ogg, Vorbis as .webm, FLAC as .flac, camera PCM as .wav and Dolby Digital as .mka, and the result explains why. If you need a file that plays everywhere, use MP4 to MP3 instead; that path re-encodes once.

How to use

Drop MP4 videos onto the box, or tap to pick them from your gallery.
Nothing to set: the sound is copied as it is. Leave "Write tags" on to keep the video's title.
Optional: open "Cut a section" to keep only part of the sound.
Press Extract, then read each result: size, length and notes.
Download each file, or everything as a ZIP.

FAQ

Is M4A the same as AAC?

AAC is the codec, M4A the file around it. A raw .aac file has no seeking index or tags, so M4A is the better container for the same AAC packets.

Can I shrink the M4A?

Not without re-encoding, which this page avoids by design. For a smaller file, convert to MP3 at a lower bitrate (96 kbps mono for speech) in MP4 to MP3.

Does it keep the video's title?

Yes, with "Write tags" on: title, artist and date stored in the video are written to the M4A; otherwise the file name is used as the title.

Related tools

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