G.728

G.728 is a ITU-T standard for speech coding operating at 16 kbit/s. Technology used is LD-CELP, low-delay code excited linear prediction. Delay of the codec is only 5 samples (0.625 ms). The linear prediction is calculated backwards with a 50th order LPC filter. The excitation is generated with gain scaled VQ. The standard was finished in 1992 in the form of algorithm exact floating point code. In 1994 a bit exact fixed point codec was released. G.728 passes low bit rate modem signals up to 2400 bit/s. Also network signaling goes through. The complexity of the codec is 30 MIPS. 2 kilobytes of RAM is needed for codebooks.

See also

*G.711 (a-law and mu-law/u-law)
*G.18
*G.719
*G.722
*G.722.1
*G.722.2
*G.723
*G.723.1
*G.726
*G.729
*G.729a
*List of codecs

External links

* [http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-G.728 ITU-T G.728 page]
* [ftp://svr-ftp.eng.cam.ac.uk/pub/comp.speech/coding/ldcelp-2.0.tar.gz C source code for G.728]