AES Standards News Blog

September 2011

AES60-2011 standard for core audio metadata published

AES60-2011 addresses the creation, management and preservation of material that can be re-used as originally produced, or may provide input material for new production projects. Material is expected to be exchanged between various organisations or between production facilities in a distributed environment.

The core set of metadata presented in this specification is a co-publication of EBU Tech3293-2008 EBU Core, itself an extension to and a refinement of the Dublin Core. EBUCore is a minimum list of attributes characterizing video and / or audio media resources. An XML representation is also provided in case this metadata would be implemented, for example in archive exchange projects using the Open Archive Initiative's Protocol for Metadata Harvesting (OAI-PMH).

Posted: Thursday, September 22, 2011

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AES57-2011 Metadata - Audio object structures for preservation and restoration

AES57-2011 sets out the vocabulary to be used in describing digital and analog audio formats, including both those formats that exist in some tangible form such as a reel of tape and those that exist only as a set of bits, untied to a single audio carrier, such as a broadcast wave file. This vocabulary takes the form of an Extensible Markup Language (XML) schema. By doing so it provides a structured human readable instance document that can be easily parsed and manipulated using any of a number of freely available programming libraries and tools. The schema is designed for flexibility, providing a number of data elements that are optional. This is necessary since often there will be certain information that cannot be known, particularly in archive settings where technicians are asked to preserve materials that have little or no accompanying documentation. As a result the base set of required elements does not necessarily represent the minimal description necessary for preservation, but rather is the set of elements that is expected to be known or determinable at a minimum.

Posted: Thursday, September 22, 2011

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New revision of AES50, High-resolution multi-channel audio interconnection (HRMAI)

AES50-2011, AES standard for digital audio engineering - High-resolution multi-channel audio interconnection (HRMAI) has been published.  This new edition revises AES50-2005 and contains amendments resulting from a real-world implementation of the standard.

AES50 specifies a means to carry multiple channels of digital audio in AES3 or bit-stream formats, plus system synchronisation information, over a structured data cable using the IEEE Std 802.3 physical layer. It includes a means to convey arbitrary packet-based data over the link, in addition to the specified audio interconnection.

HRMAI provides a professional multi-channel audio interconnection with a number of distinctive characteristics:

• Support for a wide range of commonly-used digital audio coding formats, including “high-resolution” formats such as high sample-rate linear PCM, and one-bit delta-sigma modulated formats.

• Low and deterministic latency (< 100 μs)

• Use of ubiquitous “Category-5” data cable

• Interconnect span up to 100 m

• High-quality full-duplex clocks transmitted in parallel with audio data

• Full-duplex audio interconnection

• 5 Mbit/sec full-duplex auxiliary data connection, compatible with Ethernet networks.

HRMAI is a high-performance point-to-point audio interconnection, rather than a network (although the auxiliary data may operate as a true network, independently of the audio). It is thus an alternative to AES10 (MADI). AES10 lacks many of the features listed above, which are enabled by developments in underlying technology in the thirteen years since AES10 was introduced. However, for applications which do not need these additional facilities, AES10 will continue to be appropriate.

Posted: Thursday, September 22, 2011

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New revision of AES-R6, Guidelines for AES50

 AES-R6-2011, AES project report - Guidelines for AES standard for digital audio engineering - High resolution multi-channel audio interconnection (HRMAI), AES50 has been published

This edition revises AES-R6-2005 to complement the latest revision of AES50.

This report is intended to accompany AES50, “High-resolution multi-channel audio interconnection”. It provides additional background, rationale and implementation advice and should be read in conjunction with AES50-2011 which revises the earlier AES50-2005. In particular, the first clause of this document provides an overview of the technology, which may aid understanding of the context of the standard.

The High Resolution Multi-channel Audio Interconnection provides a bi-directional, point-to-point connection for up to 48 channels of digital audio in a variety of formats. The link uses a single Category 5 (or better) structured-wiring data cable, and is designed for operation in a studio environment.

The system uses the 100Base-TX physical layer of Fast Ethernet (ISO/IEC 8802.3:2000(E) Sections 22/23, together with ANSI X3.263-1995) to transfer framed digital audio data. Audio synchronization is maintained by transmitting a 64fs (for example, 2,8224 MHz, if fs = 44,1 kHz) audio clock signal in parallel with the audio data, utilising the extra signal pairs on a structured wiring data cable.

Throughout this document, the term “fs” is used to denote a base audio sampling frequency. This may be 44,1 kHz or 48 kHz, irrespective of sampling frequency multipliers typically used for high-resolution digital audio (e.g. 2, 4, 8). If variable sample rate operation (“varispeed”) is required, fs may range from 44,1 kHz -12,5 % to 48 kHz +12,5 % (38,5875 kHz to 54 kHz). Varispeed capability is optional.

Posted: Thursday, September 22, 2011

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