G.723标准

Draft Recommendation G.723
Dual Rate Speech Coder for Multimedia Communications Transmitting at 5.3 & 6.3 kbit/s
1. Introduction
1.1 Scope
This recommendation specifies a coded representation that can be used for compressing the speech or other audio signal component of multimedia services at a very low bit rate. In the design of this coder, the principal application considered was very low bit rate visual telephony as part of the overall H.324 family of standards.
1.2 Bit rates
This coder has two bit rates associated with it.  These are 5.3 and 6.3 kbit/s.  The higher bit rate has greater quality.  The lower bit rate gives good quality and provides system designers with additional flexibility. Both rates are a mandatory part of the encoder and decoder. It is possible to switch between the two rates at any 30 ms frame boundary.  An option for variable rate operation using discontinuous transmission and noise fill during non-speech intervals is also possible.