Summary and References
The knowledge of delay encountered while transmitting audio data is key to designing time critical systems. We have the algorithmic delay encountered in MPEG audio codecs and looked at the modules which contribute to this delay. We have also looked at how to synchronize the parametric coding tools to the core waveform coding algorithms. Table 1 summarizes the algorithmic delay in various codecs discussed.
Table 1. Algorithmic Delay in MPEG Audio codecs
We observe that achieving a good quality at lower bit rates comes at the cost of delay parameter as in AAC-LC and AAC-LD. AAC-LD being the least delay codec is suited for telephony and conferencing applications while codecs like HE-AAC and MPEG Surround are suited for broadcast and streaming applications due to the advantage they offer in terms of bit rate and audio quality.
The delays of the popular audio codecs are derived, thus serving as a ready reference for designs needing A/V sync, in transcoder applications for broadcast space, conferencing and for other real-time systems which have a delay budget.
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5. ISO/IEC MPEG Audio Codec Specifications.
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