In telecommunications and electronics, G.711 is an ITU-T standard for the digital encoding of audio signals with a bandwidth of up to 4 kHz, such as voice. It is based on PCM and is the most widely used coding technique in circuit-switched telephone networks.
In G.711 encoding, the audio signal is sampled at a frequency of 8 kHz, resulting in 8000 samples per second. Each sample is then quantized to 256 levels and represented with 8 bits. The resulting bitstream is therefore 64 kbit/s and can be inserted into a time slot in the lower-level frame of the PDH hierarchy.
The quantization levels are not evenly spaced but have a logarithmic spacing thanks to the use of the companding technique, which allows for a better signal-to-noise ratio. Two quantization laws are specified: the μ-law (used in North America and Japan) and the A-law (used in the rest of the world).
In the absence of errors, G.711 encoding guarantees good voice quality with a MOS (Mean Opinion Score) higher than 4.
To convert files into these formats for free, you can use the G711.org website
