The AES11 standard published by the
Audio Engineering Society provides a systematic approach to the
synchronization of digital audio signals.
AES11 recommends using an
AES3
AES3 is a standard for the exchange of digital audio signals between professional audio devices. An AES3 signal can carry two channels of pulse-code-modulated digital audio over several transmission media including balanced lines, unbalanced ...
signal to distribute audio clocks within a facility. In this application, the connection is referred to as a Digital Audio Reference Signal (DARS).
Further recommendations are made concerning the accuracy of sample clocks as embodied in the interface signal and the use of this format as a convenient synchronization reference where signals must be rendered co-timed for digital processing. Synchronism is defined, and limits are given which take account of relevant timing uncertainties encountered in an audio studio.
Related developments
AES11 Annex D (in the November 2005 or later printing or version) shows an example method to provide
isochronous
A sequence of events is isochronous if the events occur regularly, or at equal time intervals. The term ''isochronous'' is used in several technical contexts, but usually refers to the primary subject maintaining a constant period or interval ( ...
timing relationships for distributed AES3 structures over asynchronous networks such as
AES47
AES47 is a standard which describes a method for transporting AES3 professional digital audio streams over Asynchronous Transfer Mode (ATM) networks.
The Audio Engineering Society (AES) published AES47 in 2002. The method described by AES47 is al ...
where reference signals may be locked to common timing sources such as
GPS
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...
.
In addition, the
Audio Engineering Society has now published a related standard called
AES53, that specifies how the timing markers already specified in
AES47
AES47 is a standard which describes a method for transporting AES3 professional digital audio streams over Asynchronous Transfer Mode (ATM) networks.
The Audio Engineering Society (AES) published AES47 in 2002. The method described by AES47 is al ...
may be used to associate an absolute time-stamp with individual audio samples. This may be closely associated with AES11 and used to provide a way of aligning streams from disparate sources, including synchronizing audio to video in networked structures.
The media profile defined in annex A of
AES67
AES67 is a technical standard for audio over IP and audio over Ethernet (AoE) interoperability. The standard was developed by the Audio Engineering Society and first published in September 2013. It is a layer 3 protocol suite based on existing ...
provides a means of using AES11 synchronization via the
Precision Time Protocol
The Precision Time Protocol (PTP) is a protocol used to synchronize clocks throughout a computer network. On a local area network, it achieves clock accuracy in the sub-microsecond range, making it suitable for measurement and control systems. ...
.
References
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Audio engineering
Sound
Broadcast engineering
Audio Engineering Society standards