Three AAC bitrates
Choose 128 kbps for speech, 192 kbps for balance, or 256 kbps for music-oriented output.
MP4 to M4A Converter
Convert the first audio track in an MP4 to AAC in an M4A file at 128, 192, or 256 kbps. Trim and process locally without uploading the video.
Local conversion workspace
Convert video to audio
Your video stays on this device. Processing starts only after you click Convert.
0 bytes uploaded
0 bytes uploadedMulti-thread mode is used only when this browser supports SharedArrayBuffer and cross-origin isolation.
MP4 to M4A
Compact AAC audio with explicit trade-offs
Create an audio-only M4A for modern playback without claiming a lossless stream copy.
Honest re-encoding
Current M4A mode decodes and encodes AAC even when the MP4 may already contain AAC.
Audio-only result
Video, captions, and visual metadata are removed while the first audio stream is converted.
Delivery workflow
How to convert MP4 to M4A
Use M4A when efficient playback matters more than an editing-grade PCM file.
Choose the MP4
Select one local file up to 500 MB and let the browser read its duration.
Choose range and bitrate
Trim first, then select 128, 192, or 256 kbps according to the content.
Check the M4A
Listen to the result in its intended phone, player, or podcast workflow before removing the source.
Local conversion
No MP4 upload is required
The AAC encoder runs through ffmpeg.wasm in the current browser session.
- Video and output stay on the device
- Processing begins only after Convert is selected
- Worker cleanup follows completion or cancellation
FAQ
MP4 to M4A questions
Clarifying containers, AAC, re-encoding, quality, and compatibility.
They are related MPEG-4 containers, but MP4 commonly signals video plus audio while M4A normally signals audio-only content.
No. The current M4A preset uses the AAC encoder at the selected bitrate. Use Original mode when avoiding a new encode is the priority.
128 kbps is compact for speech, 192 kbps is a balanced default, and 256 kbps is the highest available M4A preset.
Size is determined mainly by bitrate and duration. A 256 kbps M4A will be larger than a 128 or 192 kbps MP3 of the same length.
Original mode may contain an audio codec that ordinary phone players cannot open, so it uses MKA rather than promising M4A compatibility.
No. M4A mode re-encodes the selected range. Packet-boundary trimming applies specifically to Original stream-copy mode.