What? Most all FLAC is created (converted) from a WAV source. If your source is MP3, then yes, FLAC is irrelevant... But FLAC is basically a lossless compression format for WAV.
I'm really confused by what you're talking about lol... especially "up"convert...??? WAV is the ultimate lossless audio on PC. It really doesn't get any better than WAV. There is no "up" from WAV. FLAC is a compression format for WAV, that does not lose any data. The output of FLAC will be identical to the WAV file, even though its compressed. MP3 is a compression format for WAV that loses data, and will not be identical to the original WAV file.
In 1988, Apple developed the Audio Interchange File Format (AIFF), which is uncompressed pulse code modulation (PCM). PCM is what is stored on CDs, so any Mac with a CD-ROM drive attached will recognize the PCM information on Red Book audio CD's as AIFF files.
Inexplicably, 3 years later, Microsoft and IBM developed the Resource Interchange File Format (RIFF) in 1991, of which the WAV format is one implementation. RIFF doesn't store PCM. Instead it stores various formats of data in 4 byte "chunks."
Depending on the audio file format specified, one can always distinguish a Windows user from an audio professional (or a Mac user), because since about 1990, the vast majority of professional audio recording (tracking, mixing and mastering) studios have been exclusively Mac shops, including such greats as Skywalker Sound and Abbey Road Studios.
All these formats, IFF, AIFF, and RIFF, use named chunks for organization, and store PCM basically the same way, though there are other payloads possible.
My post was BS. The reason Macs became ubiquitous in audio had nothing to do with file formats and likely had everything to do with pro audio software and hardware developers that initially ignored Windows and PCs, and by the time these became platform independent, Mac was too ingrained to be dislodged. But AIFF does have smooth and sexy contours compared to WAV's clunky aesthetic. There I go again.
PSA: If you want to recreate the original file (WAV, AIFF, etc), including metadata, you should use the --keep-foreign-metadata switch to flac, otherwise it only preserves what’s needed for the audio.
I'm really confused by what you're talking about lol... especially "up"convert...??? WAV is the ultimate lossless audio on PC. It really doesn't get any better than WAV. There is no "up" from WAV. FLAC is a compression format for WAV, that does not lose any data. The output of FLAC will be identical to the WAV file, even though its compressed. MP3 is a compression format for WAV that loses data, and will not be identical to the original WAV file.