GPSYCHO

A GPL'd Psycho-Acoustic Model

c. 1999  Mark Taylor


GPSYCHO is an open source psycho-acoustic model for ISO based MP3 encoders.  GPSYCHO fixes some substantial bugs in the ISO demonstration source psycho-acoustic model (ISO psy-model). In addition,  GPSYCHO adds mid/side stereo, real bit reservoir control, much improved critical band bit allocation routines, variable bit rate (optional) and very good pre-echo control.  At 128kbs, the quality is significantly better than that produced by the ISO psy-model (as found in almost all other free encoders).  An example of these improvements is shown in Screenshots .  GPSYCHO is close to the quality of the FhG encoder, but there is still room for improvement.  Read on if you want to help!

As this code is released under the GPL, it can only be used in other GPL'd  projects.  I would also encourage others to help improve GPSYCHO.  Some things that would help:


Quality Information and Listening Tests


Notes on GPSYCHO variable bit rate (VBR)

Notes on GPSYCHO Mid/Side Stereo

Notes on GPSYCHO outer_loop quantization algorithm


New Features (which may need some tuning):

Features to try out:

Bug fixes:

Things I've learned from analyzing FhG produced .mp3 frames (layer 3, 128kbs):