Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 36. Chapters: Speech coding, Linear predictive coding, Vocoder, Speex, G.711, G.723.1, Adaptive Multi-Rate audio codec, Adaptive Multi-Rate Wideband, Secure voice, Secure Communications Interoperability Protocol, Mixed Excitation Linear Prediction, G.729, G.722.1, PESQ, Code-excited linear prediction, Extended Adaptive Multi-Rate - Wideband, PSQM, G.718, Enhanced full rate, CELT, Mean opinion score, Adaptive DPCM, Continuously variable slope delta modulation, SILK, G.719, Algebraic Code Excited Linear Prediction, G.726, Harmonic Vector Excitation Coding, Advanced Multi-Band Excitation, Selectable Mode Vocoder, QCELP, RALCWI, Internet Low Bit Rate Codec, SVOPC, Enhanced Variable Rate Codec B, Vector sum excited linear prediction, G.729.1, Half Rate, G.728, Variable-Rate Multimode Wideband, FS-1015, Digital Speech Standard, RTAudio, Internet Speech Audio Codec, FS-1016, IS-641, Long-term Predicted Excitation Coding, PDC-EFR, EDACS Provoice, Residual-excited linear prediction, PDC-HR, Improved Multi-Band Excitation, Relaxed code excited linear prediction, 4GV, MPC-MLQ. Excerpt: A vocoder (, short for voice encoder) is an analysis/synthesis system, mostly used for speech. In the encoder, the input is passed through a multiband filter, each band is passed through an envelope follower, and the control signals from the envelope followers are communicated to the decoder. The decoder applies these (amplitude) control signals to corresponding filters in the (re)synthesizer. It was originally developed as a speech coder for telecommunications applications in the 1930s, the idea being to code speech for transmission. Its primary use in this fashion is for secure radio communication, where voice has to be encrypted and then transmitted. The advantage of this method of "encryption" is that no 'signal' is sent, but rather envelopes of the band...