PCMU

PCMU, also known as G.711 mu-law, is a non-linear, 8-bit per sample, speech-audio compression algorithm. It is standardized by the ITU-T under recommendation G.711. PCMU is primarily used for encoding telephone-quality speech.

The algorithm uses a mu-law companding technique to compress the dynamic range of the speech signal. This means that quieter sounds are amplified more than louder sounds, which helps to reduce quantization noise and improve the perceived quality of speech, especially in systems with limited bandwidth or dynamic range. PCMU is a variant of G.711, with a specific companding curve denoted by 'mu' (μ).

PCMU is a lossy compression algorithm, meaning that some information is lost during the compression process. However, for speech, the loss is generally imperceptible to human listeners. The uncompressed audio data is 64 kbit/s.

PCMU is widely used in Voice over IP (VoIP) systems, particularly in North America and Japan. It is also used in traditional digital telephony systems. Due to its simplicity and low computational requirements, PCMU remains a popular choice for real-time audio transmission where low latency is critical. It is often used in conjunction with other codecs or protocols.