Over the last decade the way we find, store, and listen to music has undergone a huge change. Online media has changed many aspects of the audio industry, but some things just don’t change. The debate over audio quality still goes on. Ethernet AVB, USB Audio Class 2.0 aid audio quality article discusses on some facets of audio quality and how they relate to USB and Ethernet. It has few points really worth to share.
CDs are sampled at 44.1 kHz using 16-bit samples. Most pro audio equipment now supports sample rates of 96 kHz, and some even support 192 kHz. High-quality audio probably demands data rates of at least 128 kbits/s in AAC forma (AAC at 256 kbits/s is the default encoding used by Apple iTunes). There are a number of other audio codec “standards” around, including FLAC (Free Lossless Audio Codec).
According to Ethernet AVB, USB Audio Class 2.0 aid audio quality article USB is ubiquitous and well suited to audio. USB 2.0 High Speed and USB Audio Class 2.0 (a driver for any USB 2.0 port) include a number of features to ensure the audio is transferred reliably and with high quality: USB Audio Class 2.0 enables 192-kHz, and even 384-kHz, 24-bit audio, and many audio channels. It allows also low latency and asynchronous clocking of D/A converters. Articles USB audio simplified and USB-to-I2S audio bridge chip simplifies audio design give some more details on USB audio.
The interest in audio over Ethernet is increasing. Ethernet AVB, USB Audio Class 2.0 aid audio quality article mentions that in live sound and professional applications Ethernet has found a place to distribute audio signals. Ethernet Audio Video Bridging addresses this problem related to reliably transporting audio by providing reliable transport of audio across Ethernet networks. AVB is a collection of IEEE standards which augment Ethernet to provide functionality needed for AV distribution in professional and consumer applications, and is even finding its way into automotive.
Many other audio over Ethernet solutions also exist and are used. From them first comes to my mind are CobraNet (first commercially successful implementation of audio over Ethernet), RockNet and NetJack. Audio over Ethernet is a nowadays a viable alternative to analog audio, which suffers from signal degradation over long cable runs due to electromagnetic interference, high-frequency attenuation, and voltage drop. Additionally, the use of digital multiplexing allows audio to be transmitted using much less cabling than analog audio.