WAV to MP3
Compress an uncompressed WAV recording into MP3. This is the one pair here where real compression happens for the first time, so the file shrinks by roughly a factor of ten at the default quality.
WAV to MP3 turns an uncompressed recording into a genuinely smaller MP3, at a quality preset, medium by default. Because WAV stores every sample raw, this is the only pair in this batch where real compression starts for the first time, cutting the size down by roughly ten times. Encoding runs through WebCodecs, so this page needs a browser tab.
Questions
How much smaller does the file get?
Roughly a factor of ten at the default quality, the largest size drop of any pair here, since WAV stores audio completely uncompressed and this is the first real compression the audio goes through.
Is this lossy?
Yes. MP3 discards audio detail to reach that size, controlled by the quality option, low, medium or high, medium by default. The WAV itself carries no loss going in, so this conversion is where the loss starts.
Which engine handles this, and where can it run?
mediabunny and WebCodecs decode the uncompressed WAV, and mediabunny loads a LAME-based MP3 extension on demand as a separate chunk to encode the result. This is browser only; the command line and MCP refuse it and point to the web page.
What size should I expect?
A real MP3 comfortably over a kilobyte for a couple of seconds of audio in the fixture test, roughly a tenth of what the equivalent WAV needs for the same duration.
What is the reverse page?
MP3 to WAV runs the opposite direction, the reverse pair of this one, decoding the MP3 back to uncompressed samples without restoring anything the MP3 discarded.