MP4 to M4A
Save an MP4’s AAC audio as an M4A, with no re-encoding. Nothing is uploaded.
Drop MP4 files here
Converted on your device. Files are never uploaded.
Up to 20 files at a time.
An M4A is an MP4 that holds only audio, the format iTunes and iPhones use for music and recordings. Turning a video into an M4A keeps its soundtrack exactly as recorded and drops the picture. FormatJet copies the audio in your browser, so the MP4 never leaves your device.
About the formats
MP4MP4 video
MP4 is the most widely supported video format, used by phones, cameras and websites. It usually holds H.264 or HEVC video with AAC audio.
M4AM4A audio
M4A is an MP4 file that holds only audio, usually AAC. iPhones, iTunes and voice recorders use it; files are smaller than MP3 at the same quality, but some players and sites only take MP3.
Converted with Mediabunny, Media engine (FFmpeg).
Questions
Does MP4 to M4A lose quality?
No. The AAC audio track is copied into the M4A exactly as it is, without being decoded or encoded again, so it sounds identical to the MP4.
Why is the conversion so quick?
Because nothing is re-encoded. FormatJet only moves the audio from one container to another and leaves the video behind, which takes far less work than converting the sound.
Does it work in every browser?
In any browser that runs this site. Copying the audio needs no decoder, so it doesn’t depend on WebCodecs support the way MP4 to MP3 does.
Should I choose M4A or MP3?
M4A keeps the MP4’s audio untouched and plays in Apple Music, iTunes and most current players. MP3 plays on even more devices but means a second lossy encode, so use MP4 to MP3 when compatibility matters more.
MP4 to M4A with the API
The conversion API opens later this year.
curl https://api.formatjet.com/v1/convert?to=m4a \
-H "Authorization: Bearer fj_test_…" \
-F file=@input.mp4 -o output.m4a