vol36. Ethernet AVB / Milan プロトコル

技術 AVB

本日、MILANプロトコルが発表された。

Ethernet AVB/TSN に基づいたPro AV 向けのプロコトルで、Certified デバイス間の相互
動作を保証する。概要をまとめてみたい。

MILANとは？

  • AVB/TSNの上位layer(アプリ層)のプロトコル
    • Certified されたAVB/TSN デバイス間の相互接続性を保証する
    • アプリ及びNetwork layerへの要求を定義
      • compatible media streams, formats, media-clocking, redundancy
        and controller software.
  • Pro AV アプリ向け
  • 2018/6/5 にプレスリリースされた

Creators

AVnul Alliance 内のPro AV Marketの企業

  • AudioScience
  • Avid
  • Biamp
  • d&b audiotechnik
  • L-Acoustics
  • Luminex
  • Meyer Sound

概要

  • AVB protocol base (gen1)
  • Stream Format はAAF、Media Clock RecoveryにCRF、Device Discovery やConnection
    Management にAVDECCを採用
  • Redundancy に対する項目もあるが、それを実現するために、どのプロトコルをサポ
    トしないといけないかは規定していない。
  • user-driven protocolとのことなので、user の要求に基づいて、仕様が追加されていく形になるだろう

White Paper

以下、Whilte Paper のポイントを列挙

http://avnu.org/wp-content/uploads/2014/05/Milan-Whitepaper_FINAL-1.pdf

  • Ovewrview
    Milan creates the endpoint solution layer for professional
    audio equipment based on the following AVB IEEE stan-
    dards:

    Therefore, Milan defines a set of technical profiles for these
    IEEE standards dedicated to professional audio endpoints:

    • Media Clocking Specification
    • Stream Format Specification
    • Redundancy Specification
    • AVDECC Specification for Endpoint

  • Media Clocking Specification

    • What Format and Sample Rates are supported?
      • mandatory 48kHz
      • optional: 96kHz, 192kHz
    • CRF (Clock Reference Format) defined in IEEE 1722-2016.

  • Stream Format Specification

    • AAF 32bit (mandatory)
      • max 8ch per stream
    • High Capacity 32 bit (optional)
      • max 56ch per stream
    • High Capacity 24 bit (optional)
      • max 64ch per stream

  • Redundancy Specification

    • duplicating the network infrastructure into two independent logical
      networks (e.g. a broken cable or power loss of a bridge). By
      connecting endpoints to both networks, seamless redundancy can be
      achieved.
    • Milan does not specify a particular implementation, rather defines the
      gen- eral requirements that implementations must adhere to in order to
      achieve interoperability.

  • AVDECC Specification for Endpoint

    • The Milan AVDECC specification provides a consistent set of
      requirements that provides the following features:
      • Automatically discovers the addition and removal of pro audio
        devices on the network
      • Retrieves the entity model of the discovered pro audio devices
      • Connects and disconnects streams between the discovered pro audio devices
      • Obtains status information about the discovered pro audio devices
        and their connections
      • Controls the discovered pro audio devices

  • 参考
    http://avnu.org/milan/
    http://www.inavateonthenet.net/news/article/avb-based-milan-protocol-promises-to-boost-open-standards-networking