Robust MELP vocoder 2400 bps

Common description

Robust MELP vocoder with rate 2400 bit/s (RMELP 2400 bps) is intended for using in discrete channels with bit error rates (BER) up to 5-7%.

Robust MELP vocoder is built on the base of low bit rate MELP vocoder and original channel coding scheme using codes with high bit error correction capability.

Low bit rate MELP (Mixed Excitation Linear Prediction) speech coders use classical parametric model of description of speech signals. This model is implemented on the base of linear prediction filter with mixed excitation in several frequency bands.

Independent estimation of voiced/unvoiced decision in different frequency bands is providing more natural synthetic speech sounding then quality of classical LPC vocoders with binary voiced/unvoiced decision for single band.

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Implementation

RMELP 2400 bps is implemented as fixed-point ANSI-C models for PC. Real-time implementation on the base of TMS320c54x/c55x DSP families will be done in near future. Please ask for its parameters.

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Speech samples

Here you can test speech quality of RMELP 2400 bps vocoder with different BER rates by listening following speech samples:

For example here you can listen the standard MELP 2400 bps vocoder in the same channel conditions:

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