M4A audio export — Input checklist

Worked example

Before exporting M4A, find out what is inside the source: an .m4a can hold AAC or Apple Lossless, and a protected track may not open.

Take a musician who wants FLAC masters on a phone. A 3-minute 44.1 kHz stereo FLAC is typically 15 to 25 MB, and the M4A made from it at 192 kbps will be about 4.3 MB. Before converting, play the FLAC end to end and note the duration, because the exported file must match it.

M4A is a container, not a codec. This tool always writes AAC audio into that container, so a source that is already AAC at 128 kbps gets encoded a second time. That second pass is the lossy-on-lossy trap: prefer the original WAV or FLAC when you have it, and use a previous M4A only when nothing better exists.

The mistake that wastes the most time is feeding in a file that only looks like audio. A voice memo recorded as .m4a works, but an iTunes-style purchase with copy protection, or a .mp4 that is really a video, will not. Fix it by dropping the file into a plain media player first; if it plays there and the converter rejects it, check that it is not a video container.

A concrete check: open the file properties or a player info panel and write down the sample rate (44.1 or 48 kHz) and channel count. You will compare them with the exported file later.

Accessible source audio

M4A export

Album art and tags may not be carried across a re-encode, so keep the original file if those matter.