An Adaptive Audio Quantizer for Voip Systems

The Internet evolution has been requiring the development of new technology to support multimedia transmission such as images, database access, audio and video in realtime. Such development needs new services and supports like the voice over IP (VoIP) which has a main motivation in the low cost communication and management. VoIP systems have motivated this work which proposes an adaptive audio quantizer named IQ (intervalar quantizer) to reduce the data dimensionality and consequently the entropy, what allows better audio compression. This quantizer is adaptive because it has an error tolerance parameter which can be varied according to the available network bandwidth, allowing to adapt communication. After transmitting, the audio is improved by using a filter with complex poles in the Z plan. This filter attenuates non-important frequencies, privileging the sensitive ones to human audition. Results confirm that IQ and the filter offer good quality (measured using the mean opinion score metrics) and compress ratio.