The first WMA codec was based on earlier work by Henrique Malvar and his team which was transferred to the Windows Media team at Microsoft.[4] Malvar was a senior researcher and manager of the Signal Processing Group at Microsoft Research,[5] whose team worked on the MSAudio project.[6] The first finalized codec was initially referred to as MSAudio 4.0.[7][8] It was later officially released as Windows Media Audio,[9] as part of Windows Media Technologies 4.0. Microsoft claimed that WMA could produce files that were half the size of equivalent-quality MP3 files;[10] Microsoft also claimed that WMA delivered "near CD-quality" audio at 64 kbit/s.[10] The former claim however was rejected by some audiophiles.[11] RealNetworks also challenged Microsoft's claims regarding WMA's superior audio quality compared to RealAudio.[9]