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The bit allocation is the same as that given in table 1. Therefore, the version is bit stream interoperable with the full (G.729) version. It has also the same delay (speech frame of 10 ms and look ahead of 5 ms). The major algorithmic changes are summarised below. The perceptual weighting filter is simplified. The open-loop pitch analysis is simplified by using decimation. The computation for the impulse response is reduced. The search of the adaptive and fixed coodbook are modified. The harmonic postfilter is replaced by a simple integer delay. The concealment of frame erasure detection is simplified. No voicing detection is used therefore, the excitation is always the addition of both adaptive and fixed codebook contributions. |