Erik Ekudden

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In this paper, we describe the Adaptive Multi-Rate (AMR) speech coder currently under standardization for GSM systems as part of the AMR speech service. The coder is a multi-rate ACELP coder with 8 modes operating at bit-rates from 12.2 kbit/s down to 4.75 kbitls. The coder modes are integrated in a common structure where the bit-rate scalability is(More)
In CELP, the use of codebooks with entries with only a few non-zero samples provides high speech quality and facilitates fast computation. With decreasing bit-rate, the intervals between the pulses increase, and the quality of the reconstructed signal begins to su er from a particular type of artifact, which is strongest for noise-like segments. In this(More)
This paper describes the 6.4 kbit/s CS-ACELP coder being standardized as annex D to ITU-T G.729. The coder is based on the same building blocks as the 8 kbit/s G.729 to facilitate low complexity extensions to G.729 in terms of additional memory usage. It is fully switchable with the 8 kbit/s coder and provides additional flexibility to existing and emerging(More)
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