G.728

From VideoLAN Wiki

??	This is a video codec. The name to use at the command line is unknown.

G.728 is a codec for storing speech created by ITU-T. It is based on Low Delay Code Excited Linear Prediction (LD-CELP).

28_8

28_8 is a variation on G.728 which uses 28.8 kbits/sec. It is used in RealMedia files.