Digital Audio Interfacing and Networking 1469Bits 3–5 Encoded audio word length (see notes 1, 2, 3, and 4).
Bit 3 4 5 Audio word length if
bits 0–2 indicate max-
imum 20 bit length.Audio word length if
bits 0–2 indicate max-
imum 24 bit length.
State 0 0 0 Length not indicated,
defaultLength not indicated,
default
0 0 1 19 bits 23 bits
0 1 0 18 bits 22 bits
0 1 1 17 bits 21 bits
1 0 0 16 bits 20 bits
1 0 1 20 bits 24 bits
All other possible states of bits 3 – 5 are reserved and
are not to be used unless defined by the AES in the
future.
Bits 6–7 Alignment level indication.
Bit 6 7
State 0 0 Not indicated.
0 1 SMPTE RP155 (alignment level is 20 dB
below maximum level).
1 0 EBU R68 (alignment level is 18.06 dB
below maximum level).
1 1 Reserved for future use.
Note 1. If the default state or bits 3–5 is indicated, the receiver
should default to 20 or 24 bits as specified by bits 0–2, but allow
manual override or auto set.
Note 2. If other than the default state of bits 3–5 is indicated, the
receiver should not allow manual override or auto set.
Note 3. No matter which audio word length is indicated, the MSB
representing the signal polarity is always bit 27 of the subframe.
Note 4. Knowledge of the actual encoded audio word length can
be used to allow the receiving device to properly re-dither the
audio to a different word length if so required.
Byte 3
Bit 7 Defines the meaning of bits 0–6.
State 0 Undefined multichannel mode, default.
1 Defined multichannel modes.
Bits 0–6 Channel number if bit 7 is 0. Channel number is value
of bits 0–6 (bit 0 is LSB) plus 1.
Bits 4–6 Multichannel mode if bit 7 is 1.
Bit 4 5 6
State 0 0 0 Multichannel mode 0. Bits 0–3 specify the
channel.
1 0 0 Multichannel mode 1. Bits 0–3 specify the
channel.
0 1 0 Multichannel mode 2. Bits 0–3 specify the
channel.
1 1 0 Multichannel mode 3. Bits 0–3 specify the
channel.
1 1 1 User defined multichannel mode. Bits 0–3
specify the channel.
Bits 0–3 Channel number if bit 7 is 1. Channel number is value
of bits 0–3 (bit 0 is LSB) plus 1.
Note 1. It is intended that the defined multichannel modes will
identify mappings between channel numbers and function. Stan-
dardized mappings have yet to be defined.Table 39-1. Channel Status Data Format Details
(Continued)
Note 2. Some equipment may only consider the channel status
data carried in one of the two subframes. Therefore if both sub-
frames specify the same channel number, subframe 2 has a chan-
nel number one above channel 1 unless single channel double
sampling frequency mode is in use.
Note 3. If bit 7 is 1, bits 0–3 correspond to the consumer mode
channel status specified in IEC 60958-3. Consumer mode channel
A is equivalent to channel 2, and Consumer mode channel B to
channel 3 and so on.
Byte 4
Bits 0–1 Digital audio reference signal to the AES11 Standard.
Bit 0 1
State 0 0 This is not a reference signal, default.
0 1 Grade 1 reference signal.
1 0 Grade 2 reference signal.
1 1 Reserved for future use.
Bit 2 Reserved.
Bits 3–6 Sampling frequency.
Bit 3 4 5 6
State 0 0 0 0 No frequency indicated, default.
1 0 0 0 24 kHz.
0 1 0 0 96 kHz.
1 1 0 0 192 kHz.
0 0 1 0 Reserved.
1 0 1 0 Reserved.
0 1 1 0 Reserved.
1 1 1 0 Reserved.
0 0 0 1 Reserved for vectoring.
1 0 0 1 22.05 kHz.
0 1 0 1 88.2 kHz.
1 1 0 1 176.4 kHz.
0 0 1 1 Reserved.
1 0 1 1 Reserved.
0 1 1 1 Reserved.
1 1 1 1 User defined.
Bit 7 Sampling frequency scaling flag.
0 No scaling, default.
1 Multiply sampling frequency indicated in
byte 0 bits 6–7, or byte 4 bits 3–6, by 1/1.001.
Note 1. The sampling frequency as indicated in byte 4 is indepen-
dent of the channel mode as indicated in byte 1.
Note 2. There is no requirement to use a particular sampling fre-
quency, nor to use a sampling frequency that can be indicated in
bytes 0 or 4. If the transmitter does not support indication of sam-
pling frequency, the frequency is unknown, or the sampling fre-
quency is not one that can be indicated in this byte, then bits 3–6
should be set to “0 0 0 0.”
Note 3. It is intended to assign sampling frequencies in the future
to the currently reserved states of byte 4 bits 3– 6 (except 0 0 0 1)
such that if the rates are related to 44.1 kHz bit 6 will be set, and if
they are related to 48 kHz bit 6 will be cleared. Do not use these
reserved states unless defined in the future by the AES.
Byte 5Table 39-1. Channel Status Data Format Details
(Continued)