Public MP3 Listening Test @ 128 kbps (October 2008)

A lot of development happened since the last public MP3 listening test @ 128 kbps conducted by Roberto Amorim. All encoders experienced major or minor updates that should improve audio quality or encoding speed and we have a totally new encoder on board.

The purpose of this test is to find out which popular MP3 VBR encoder outputs the best quality on bitrates around 128 kbps.

Warning: As Hydrogenaudio Forums members and I found out, there is a bug in the iTunes MP3 encoder that is present in all iTunes versions since 5.0.1.4 (including the tested version 8.0.1.11). The problem manifests itself only on multi-core CPUs (both PCs and Macs) and leads to a significantly lower bitrate of the encoded samples. Apple engineers confirmed our findings and assured me that the next iTunes release will contain a fix for this problem. Please notice that the only functioning work-around is to disable all but one core in your computer's BIOS or to start Windows with the /numproc=1 parameter. Setting the iTunes process affinity to one core does NOT help.

If you have any questions, feel free to contact me via e-mail: mail@listening-tests....

Best regards,
Sebastian Mares