The MP3 format has difficulty storing content above 16 KHz without sacrificing quality and increasing the bitrate requirements of the lower frequency bands.
The MP3 format has a technical limitation that forces a trade-off: the more accurately the highest frequency band (16 KHz and up, normally) is encoded, the greater the space required to encode the lower frequency bands with similar quality. In other words, if the highest frequencies are preserved well, the quality of the much-more audible lower frequencies is sacrificed, and the bitrate has to be increased significantly to compensate, and it might not always be possible to fully compensate because of the 320 kbps limit on bitrate.
I think the main issue is that after the 3.99.5 release the main SVNbranch (trunk) has been (mis-)used a a feature branch for someimprovements to the psycho-acoustic model. However, these improvementsnever really took off, the changes were rather considered asregressions and after the main developer lost time (and/ot interest?),nobody really dared to touch that code.Then came the first patches and fixes addressed at the 3.99.5 releaseand were applied on top of the current development state, but nobodydared to do the overdue point release because of all the other changesto the code . As such, the code wasn't touched at all anymore,because it couldn't get released as is and no preparations were evermade to do a point release with minimal changes to the previous one.This is at least how I perceived what has happened. However, thisdoesn't mean that it really was like this.
What do you think? Is it still okay to use lame3100m?