I heard an interview a month or two back with one of
the developers of the
MP3 format. He said that the real litmus test for them was the acappella
version of "Tom's Diner" by Suzanne Vega. Every time they thought they
had
problems with artifacting licked, they'd try to encode that song. It was
only when they encoded that acceptably that they felt they were successful.
That was Brandenburg IIRC, and an early FhG encoder. Many mp3
encoders still have trouble with that track because of all the HF
content.
I know I sound like a broken record, but a format is only as good as
its encoder, and each has many different encoders. Encoding is
NP-hard.
Monty