AES Standards News Blog

A call for comment on draft revised AES11-xxxx, AES recommended practice for digital audio engineering - Synchronization of digital audio equipment in studio operations, has been published 2009-02-23

http://www.aes.org/standards/comments/cfc-draft-rev-aes11-xxxx.cfm

This standard specifies test methods for estimating the storage life expectancy (LE) of information stored on compact discs (CD-ROM). Only the effects of temperature and relative humidity are considered. Block error rate (BLER) is the measured response and the end-of-life criterion. An Eyring model is developed from accelerated test results. Data are normalized to 25 °C and 50 % relative humidity, and the LE, percent compliance, and confidence intervals at these conditions are calculated.

http://www.aes.org/publications/standards/search.cfm?docID=30

Weighted peak flutter is measured using a 3150-Hz tone transmitted through the equipment. The tone is frequency demodulated, frequency-response weighted, peak-to-peak detected, time-response weighted, and read out on a two-sigma statistical voltmeter over a period of at least 5 s. Results are reported as "weighted peak flutter of the recorder (or reproducer, or recording/reproducing system): ± __ percent."

A toleranced graph and table give the frequency-response weighting (approximately at 6-dB-per-octave drop above and below 4 Hz, with an additional drop below 0,5 Hz). The statistical voltmeter is described; it is preferred, and replaces the quasi-peak meter (now deprecated) of the original standard.

Good engineering practices are given for the meter design. The rationale for this standard is given in an annex. This standard has technical requirements identical to IEC 60386 Ed.1 1972 as amended by IEC 60386-am1, 1988. Measurement results according to this standard are identical to those made according to the older standards originally published as IEEE Std-193, IEC 60386 Ed.1 1972, CCIR 409-2, and DIN 45 507.

http://www.aes.org/publications/standards/search.cfm?docID=15

This standard provides recommendations concerning the storage conditions, storage facilities, enclosures, and inspection for recorded polyester-base magnetic tapes in roll form. It covers analog and digital tape and includes tape made for audio, video, instrumentation, and computer use.

http://www.aes.org/publications/standards/search.cfm?docID=25

This standard describes the data organization for a multichannel audio digital interface. It includes a bit-level description, features in common with the AES3 two-channel format, and the data rates required for its utilization. The specification provides for the serial digital transmission of 32, 56, or 64 channels of linearly represented digital audio data at a common sampling frequency within the range 32 kHz to 96 kHz, having a resolution of up to 24 bits per channel. The format makes possible the transmission and reception of the complete 28-bit channel word (excluding preamble) as specified in AES3, providing for the validity, user, channel status, and parity information allowable under that standard. The transmission format is of the asynchronous simplex type and is specified for a single 75-ohm coaxial cable point-to-point interconnection or the use of fibre-optic cables.

This revision includes minor changes to conform to recent revisions of AES3 and AES5 and provides clarifications of sync reference signals and link transmission-rate tolerance, and references for 'NRZI' and the 4B5B coding scheme.

http://www.aes.org/publications/standards/search.cfm?docID=17

The 32-bit address space of a Wave file limits its maximum size to 4 GB. Some practical computer systems may impose a lower limit of 2 GB. This is not a significant obstacle for mono files at basic rate sampling frequencies, but the limitation becomes increasingly significant as the number of channels in the file is increased or when double- or quadruple-rate sampling frequencies are used. The Extended Broadcast Wave Format (BWF-E) file format described in this amendment is designed to be a compatible extension of the Broadcast Wave Format (BWF) already defined in AES31-2. It extends the maximum size capabilities of the RIFF/WAVE format by increasing its address space to 64 bits where necessary. BWF-E is also designed to be mutually compatible with the EBU T3306 "RF64" extended format.

http://www.aes.org/publications/standards/search.cfm?docID=74

This Amendment adds code points in the ATM Adaptation Layer Parameters Information Element to signal that the time to which each audio sample relates can be identified as specified in AES53.

http://www.aes.org/publications/standards/search.cfm?docID=75