EtherSound
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EtherSound is one of several Audio over Ethernet technologies currently used in audio engineering and broadcast engineering applications. EtherSound is developed and licensed by Digigram [1]. Fostex NetCIRA products [2] use EtherSound technology, as do products from:
- Allen & Heath [3]
- Archean Technologies [4]
- Audio Performance [5]
- AuviTran [6]
- Bittner Audio International GmbH [7]
- Bouyer [8]
- CAMCO [9]
- DiGiCo [10]
- Digigram [11]
- Focusrite Audio Engineering Ltd] [12]
- InnovaSON [13]
- Klein + Hummel [14]
- Martin Audio Ltd. [15]
- Mediachip Sistemas Multimedia LDA [16]
- Nexo [17]
- Peavey Electronics Corporation [18]
- Pinanson [19]
- Richmond Sound Design Ltd. [20]
- Tesi [21]
- VTG Audio [22]
- Whirlwind [23]
- Wisycom srl [24]
- Yamaha Corporation [25]
EtherSound is intended by the developer to be fully compliant with Ethernet standards, which are maintained by the IEEE 802 LAN/MAN Standards Committee of the Institute of Electrical and Electronics Engineers [26] as IEEE802.3x (Carrier Sense Multiple Access with Collision Detection (CSMA/CD) standards. Just as the IEEE defines both 100 Megabit and Gigabit Ethernet standards, EtherSound is being developed as both ES-100 (for use on dedicated 100 Megabit Ethernet networks or within a Gigabit network as a VLAN) and ES-Giga (for use on dedicated Gigabit Ethernet networks). EtherSound is compliant with IEEE Ethernet standards, so standards-compliant hardware (switches and media converters) and cables (Cat 5e or Cat 6 copper and/or fiber optic cable can be used. However, EtherSound is not designed to share Ethernet LANs with typical office operations data or Internet traffic such as email. Like all audio-over-Ethernet technologies, EtherSound adapts the non-deterministic nature of CSMA/CD protocols to provide a continuous stream of high-sample rate, 24-bit resolution audio data. The Ethernet protocol allows every device equal access to the network (Carrier Sense Multiple Access) and accepts the inevitability of "collisions" as a result. Ethernet data is sent in bursts. Ethernet frames are sent in a serial stream (one after the other) and contain addresses, protocol control information and data.EtherSound's solution to the problem of using a non-deterministic equal-priority network to transmit deterministic, prioritized audio data is proprietary, as are the solutions adopted by other audio-over-ethernet technologies.
Latency is a key specification for many users of audio-over-ethernet technologies. One of the most critical applications involves picking up sound from a vocalist's or instrumentalist's microphone on a live performance stage, mixing that signal with those received from other microphones (and performers) and delivering the mix (called a monitor mix to the performer via in-ear monitors. Latency in this application is particularly annoying to vocalists (who are, in turn, famous for annoying their monitor engineers). This is because a singer hears his or her own voice through bone conduction as well as through the outer ear. If the sound from the in-ear monitor lags the bone-conduction sound by more than a few milliseconds, phase shifts and comb filtering will become audible.
EtherSound has been engineered to deliver up to 64 channels of 48 kHz, 24-bit PCM audio data with a network latency of 125 microseconds. Each device in a daisy-chain network adds 1.5 microseconds of latency. EtherSound's network latency is stable and deterministic: the delay between any two devices on an EtherSound network can be calculated.
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Me, Ink LLC 17:00, 14 February 2007 (UTC)
