Harmonic Vector Excitation Coding

Harmonic Vector Excitation Coding ( HVXC ) is optimized for the transmission of voice method of compressing audio data. Despite very low bit rates HVXC -encoded data for the transmission of speech are useful in a acceptable quality. It is used in digital broadcasting, satellite communications and internet telephony and for language databases. This method is part of the MPEG -4 standard, it is described in ISO / IEC 14496-3.

Technology

Is a two stage codec HVXC. In the first step, the output signal with a linear predictive coding is compressed. The result is decoded and compared with the output signal. The resulting Residien (differences between output signal and the decoded signal ) are then compressed with Parametric Audio Coding one more time. In HVXC However, this algorithm is used exclusively in voiced speech for use; other signals are compressed with Code Excited Linear Prediction.

HVXC is optimized for voice transmission with variable bit rates below 2 kbit / s and fixed bit rate of 2 kbit / s and 4 kbit / s. It operates at a sampling frequency of 8 kHz, a frequency band of 300-3400 Hz and an algorithmic delay of 33.5 to 56 msec.