How does browser audio conversion work?
An audio converter decodes a supported source into raw samples and encodes those samples in a selected output format. It can make recordings compatible with another editor or player, but changing from one lossy format to another cannot restore detail already discarded from the source.
The Web Audio API decodes locally, a custom encoder produces WAV, and an unmodified lamejs dependency produces MP3. Browser codec support determines accepted inputs, and large files can exhaust device memory. Review sample rate, channels, quality, tags, and playback before deleting the original.