Padding
A method to adjust the average length of an audio frame in time to the duration of the corresponding PCM samples, by conditionally adding a slot to the audio frame.


Parameter
A variable which may take one of a large range of values. A variable which can take one of only two values is a flag and not a parameter.


Parser
Functional stage of a decoder which extracts from a coded bitstream a series of bits representing coded elements.


PCM (Pulse Code Modulation)
Coding where input signal is represented by a given number of fixed-width samples per second. Often used for the coding employed in the telephone network.


Polyphase filterbank
A set of equal bandwidth filters with special phase interrelationships, allowing for an efficient implementation of the filterbank.


Prediction
The use of a predictor to provide an estimate of the data element currently being decoded.


Prediction error
The difference between the actual value of a predicted element or data element and its predictor.


Predictor
A linear combination of previously decoded pel values or data elements.


Presentation channel
An audio channel at the output of the decoder.


Profile
A defined sub-set of the syntax of a specification.


Program
A set of main audio channels, coupling channel elements, lfe channel elements, and associated data streams intended to be decoded and played back simultaneously. A program may be defined by default or specifically by a program configuration element. A given single channel element, channel pair element, coupling channel element, lfe channel element or data channel may accompany one or more programs in any given bitstream.


Psychoacoustic model
A mathematical model of the masking behaviour of the human auditory system.