AES

Audio Engineering Society

The AES and the EBU have defined a standard for digital audio, now adopted by ANSI.

Commonly referred to as ‘AES/EBU’, this digital audio standard permits a variety of sampling frequencies, for example CDs at 44.1 kHz, or digital VTRs at 48 kHz. 48 kHz is widely accepted as the standard frequency for the post production industry. It is a serial transmission format for two-channel linearly-represented digital audio data. Each audio sample is carried by a sub-frame containing: 20 bits of sample data, 4 bits of auxiliary data (which may be used to extend the sample to 24 bits), 4 other bits of data and a 4-bit preamble. Two sub-frames make up a frame which contains one sample from each of two audio channels.

Frames are further grouped into 192 frame blocks. AES/EBU signal includes channel status data containing information about signal emphasis, sampling frequency, channel mode (stereo, mono, etc.), use of auxiliary bits (extend to 24bits or other uses), and a CRC for error checking. There are several allowed sampling frequencies within the 32 kHz to 48 kHz range, the most common of which are 44.1 kHz and 48 kHz.

Of potential interest in electronic production are the following: SC-2, Subcommittee on Digital Audio; SC-3, Subcommittee on the Preservation and Restoration of Audio Recording; and SC-4. Subcommittee on Acoustics.

For more information on this organisation please see the AES Website