Converting audio file & adjusting it's tempo



I downloaded once for trial a program for converting audio files. They claimed the conversion is done in a special way (if I remember well, they were talking of “digital” conversion) and that program enabled also to change the tempo of the file. Ultimately, I didn’t purchase it, because each conversion was very time consuming (today I am converting with the dBPowerAmp converter). However, I remember that the above mentioned program enabled also adjustment of the tempo of the audio file without changing it’s pitch, and that’s why I would like to check it again. Unfortunately, I forgot the name of that program.
Is there somebody who, by any chance, knows the name/s of such a proogram/s ? And if not, is there somebody who can recommend some good programs specially for adjustment of the tempo of audio files without changing their pitch.
Thanks in advance

P.S. I know that one can do it with Audacity, however, as fare as I remember, the above mentioned program did it better