G.711 μ-law and A-law Vocoder
Toronto, Canada - GAO Research
Inc. recommends its G.711 Vocoder implementing independent
user-callable functions that perform all of the μ-law and A-law encoding and
decoding operations. The most common application for GAO's G.711 Vocoder is
data compression over telephone networks.
G.711 vocoder provides a compression /decompression
(companding) algorithm to deliver precision transmissions of encoded speech
signals sampled at the rate of 8 kHz in conformance with the ITU-T G.711
standard. It uses pulse code
modulation (PCM) to compress, decompress, encode, and decode analog speech,
which can then be transmitted and received as binary data.
This vocoder operates at a 64
kbps bit stream. It specifies two forms of companding standards: the
µ-law and the A-law. The A-Law G.711 PCM encoder
converts 13 bit linear PCM samples into 8 bit compressed PCM (logarithmic form)
samples, and the decoder reverses the process. The µ-Law G.711 PCM encoder
converts 14 bit linear PCM samples into 8 bit compressed PCM samples.
This G.711 vocoder belongs to
GAO's family of speech vocoders Other featured products in this
line include G.729,G729A, and G.729B speech vocoder which is based
on Code Excited Linear Prediction Model (CELP) and Conjugate-Structure
Algebraic CELP (CS-ACELP) and is suitable for visual telephony, wireless
communications, and digital satellite communication systems; G.7231 vocoder which encodes 16-bit PCM samples into 16-bit code-words yielding 10 or 12
code-words per 240 sample frames for the 5.3 Kbps and 6.3 Kbps channels
respectively; and G722 vocoder. utilizing a SB-ADPCM decoder
which performs the reverse operation to the encoder.
About GAO Research Inc.
GAO Research Inc. is a
world-renowned provider of high quality, reliable telecommunications software
including embedded modem software,
fax modem software, speech
codes, and telephony software for a wide range of DSPs and microprocessors.
