Options
2008
Conference Paper
Titel
Adaptive playout for VoIP based on the enhanced low delay AAC audio codec
Alternative
Adaptive VoIP-Wiedergabe über den AAC-Audio-Codec mit geringer Verzögerung
Abstract
The MPEG-4 Enhanced Low Delay AAC (AAC-ELD) codec extends the application area of the Advanced Audio Coding (AAC) family towards high quality conversational services. Through the support of the full audio bandwidth at low delay and low bit rate, it offers excellent support for enhanced VoIP applications. It is provided a brief overview of the AAC-ELD codec and describe how its codec structure can be exploited for IP transport. The overlapping frames and excellent error concealment make it possible to use frame insertion/deletion in order to adjust the playout time to varying network delay. A playout algorithm is proposed which estimates the jitter on the network and adapts the size of the de-jitter buffer in order to minimize buffering delay and late loss. Considering typical network conditions and the same average delay, it is shown that the playout algorithm can reduce the loss rate by more than one magnitude compared to fixed playout.