Convert M4A to FLAC
Drop an .m4a file and download a FLAC holding the decoded AAC audio. Sample rate and channel count carry through untouched.
The value here is stopping further degradation. Once the audio sits in FLAC, editing and re-exporting it as many times as you like adds nothing new, because each pass starts from the same samples.
What you are actually storing
The FLAC is lossless with respect to its input, not to the original session. An M4A recorded at 128 kbps produces a large FLAC that still contains 128 kbps worth of audio information.
Nothing about this conversion is dishonest as long as the file is labeled for what it is: a lossless copy of a lossy source.
Size
Expect roughly 25 MB for a 4-minute stereo track, against about 5 MB as M4A. Long exports stream to browser disk storage when the browser provides it, so duration does not drive memory use.