How to Convert MP4 to M4A

Most MP4 videos produced today use AAC audio encoded at 128–256 kbps. M4A is also an MPEG-4 container with AAC audio. Converting MP4 to M4A is therefore a container swap, not a transcode — the audio bitstream is moved from the MP4 container to the M4A container without touching the audio data. This means the resulting M4A file is lossless relative to the original audio: no additional compression occurs, no data is discarded, and the process is essentially instant. The output file is smaller than the MP4 (because all video data is removed) with zero quality loss. This is one of the few audio conversions where quality is completely preserved.

Lecture recordings downloaded from Zoom, Teams, or YouTube often come as MP4 files. If you only need the audio for a podcast, study playlist, or transcription service, converting to M4A saves significant storage space (a one-hour video at 720p is ~500 MB; the extracted M4A audio is ~60 MB). Music videos downloaded in MP4 format can be converted to M4A for your music library — the M4A will be identical to the streaming audio quality since music video audio is typically encoded at 192–256 kbps AAC. iPhone voiceovers recorded in video apps and exported as MP4 convert cleanly to M4A for import into GarageBand or Voice Memos.

Open AudioUtils in your browser. Drag the MP4 file onto the converter. Note that large video files may take a moment to load — a 1 GB MP4 file will process in the browser but may require 1–2 minutes depending on your system. Select M4A as the output format. Because this is a container remux rather than a transcode, no quality settings appear — the output mirrors the source audio exactly. Click convert and download the M4A file. The output file size will roughly equal the audio-only portion of the original MP4. For files longer than a few minutes, AudioUtils Pro removes the 10-second preview restriction, allowing full-length M4A extraction from any video file up to 500 MB.

After conversion, verify the M4A file by playing it through your preferred app. Check for clean sync at the beginning (no leading silence or cut-off), consistent audio throughout, and correct duration. MP4 files sometimes contain multiple audio tracks — English and Spanish dubs, for example. AudioUtils extracts the first audio track by default. If you need a specific track from a multi-track MP4, you would need FFmpeg command-line access to specify the track index. For single-track MP4 files, the result is always correct. Metadata from the MP4 file (title, artist, date) may or may not transfer to the M4A depending on how the original MP4 was tagged — verify with your music player and re-tag if needed.

M4A files play natively on every iPhone and iPad via the Music app, Files app, and any third-party audio player. To add M4A files to your iPhone music library, either sync through iTunes/Finder on a Mac, AirDrop from a Mac directly to the Music app, or use iCloud Drive to transfer and then open with the Music app. Podcasting apps like Overcast and Pocket Casts play M4A files if you add them as local files. Voice Memos on iPhone also imports M4A. For editing, GarageBand on iPhone accepts M4A through the Files browser. The M4A format is Apple's native compressed audio container — there is no Apple app that cannot play it.