AET 2050 - DAW Production


8. Interconnection

Objectives:

Identify the various streaming digital formats in terms of:

  1. number of channels
  2. sample rate and bit depth
  3. physical medium
  4. clocking
  5. source or origin.

Reading:

Chapter 6.3-6.5, Desktop Audio Technology - Rumsey

Chapter 2, The Desktop Studio - Menaché


Data Formats and Packaging

Digital audio is arranged in logical methods for transmission between devices

Transmitted data includes not only audio, but information such as samplr rate, bit depth, user data and error detection.

Example: data layout for AES/EBU transmission

Data is assembled into sections known as frames and blocks.

Each frame carries the information for one sample in two channels.

Each frame has two subframes. Each subframe defines a sample value for each of two channels.

A Subframe has a length of 32 bits:

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Two Subframes are combined to make a Frame which has a length of 64 bits:

                                                                                                                               

192 frames make up a data block.

The channels status bits (30) are collected at the receiver from the 192 successive frames to form two Channel Status Blocks which consist of 192 bits each, organized into 24 bytes.

Status block data includes number of channels, sample rate, wordlength.

User bits are configured similarly. They can convey different data, such as names, adates, etc, according to system design.

TWO CHANNEL FORMATS

AES/EBU and S/PDIF use a similar method to encode data but use different cables and connectors.

AES/EBU is used primarily on professional gear

S/PDIF was created for consumer products.

A few differences in conveyed data, but mostly interchangeable

AES/EBU (Audio Engineering Society/European Broadcast Union)

aes

Data transmission speed is 64x the sampling rate (at 48 kHz, rate is 3.072 Mbps)

Transmision speed will vary with sampling rate

S/PDIF (Sony Philips Digital Interface Format)

There are two basic formats for S/PDIF:

MULTICHANNEL FORMATS

ADAT Optical (ADI)

TDIF (Tascam Digital Interface Format)

Multichannel Audio Digital Interface (MADI)

 


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