Ages back I tried comparing the quality of the fraunhoffer and xing codecs. The old xing codec had problems with general noise from the low quality algorithm, and despite Xing claiming they filtered all frequencies above 16kHz, they still got through somewhat, and the filter itself caused lots of distortion to frequencies just at the limit. No such problems with fraunhoffer. Removing high frequencies is cheating, anyway - that's just throwing data away which you want compressing. If you really don't want high frequencies, use 22 or 36kHz sampling rates.

I also came across very audible problems with a version of BladeEnc - not sure which one because I haven't managed to reproduce it myself. It would encode fine, but it would 'ring' loudly at around 15kHz - and then only in the left channel. Quite obviously a bug, which has hopefully since been fixed. It's also a bloody slow algorithm. My best efforts at optimizing it have come up with a 25% speed increase, but I don't see it getting any faster without the author rethinking some of the dreadfully slow operations performed (e.g arc tangents).

The new Xing codec in audiocatalyst sounds pretty much fine to me. I should try to analyse the results of the new codecs at some point to get a more quantitative picture of which is best.

- John.

(The above may not represent the views of Empeg :)