Paper Review:
Adaptive Playout Mechanisms for Packetized Audio Applications in Wide-Area Networks

Reviewer: Robert Dugas


The problem addressed is that of variations in network delays affecting the reception and playback of packetized audio.


Proposed and evaluated are 4 algorithms for coping with such problematic delays in audio transmission.

Main Ideas


This paper describes some useful techniques both in estimating delay, and in applying that knowledge to optimizing voice playback. As IP telephony and other packetized audio applications gain popularity, these techniques and others like them will become necessary for adapting from current circuit switched networks.
Four algorithms are presented and evaluated based on performance of the NeVoT audio terminal application. Traces are presented for loss percentages given experimentally obtained delay measurements of audio traffic between several different sites. Although the specifics of that sampling are somewhat dubious, the results presented seem to conform to expections of the effects of the different algorithms.
The techniques described in this paper will only apply well to voice audio packets. Since the author takes advantage of the silence periods inherent in human voice to adjust the buffering status, such techniques will not apply to other audio sources.
The data presented indicates that dynamic adjustment of delay measurements can enhance playback performance when applied to receiver buffering.