Appendix 6
AES/EBU interface channel status data
The 24 bytes (0-23) are arranged as in the following table:
The specific organization of the data is as follows:
Byte 0
| a Bit 0 | 0 | Consumer use of channel status block |
| 1 | Professional use of channel status block | |
| b Bit 1 | 0 | Normal audio mode |
| 1 | Non-audio mode | |
| c Bits 2-4 | Encoded audio signal emphasis | |
| bit | 234 | |
| 0 0 0 | Emphasis not indicated. Manual selection enabled | |
| 1 0 0 | No emphasis. Manual selection disabled | |
| 1 1 0 | 50/15 jus. Manual selection disabled | |
| 1 1 1 | CCITT J. 17 emphasis. Manual selection disabled | |
| All other bit states are reserved | ||
| d Bit 5 | 1 | Source sampling frequency unlocked |
| 1 | Sources sampling frequency locked | |
| e Bits 6-7 | Encoded sampling frequency | |
| bit 6 7 | ||
| 0 0 | Sampling frequency not specified. Default is 48 kHz. Manual selection enabled | |
| 0 1 | 48 kHz. Manual selection disabled | |
| 1 0 | 44.1 kHz. Manual selection disabled | |
| 1 1 | 32 kHz. Manual selection disabled. | |
Byte 1
| f Bits 0-3 | Encoded channel mode | |
| bit | 0 1 2 3 | |
| 0 0 0 0 | Mode not indicated. Manual selection enabled | |
| 0 0 0 1 | Two channel mode. Manual selection disabled | |
| 0 0 1 0 | Single channel (Mono) mode. Manual selection disabled | |
| 0 0 1 1 | Primary/secondary mode (sub-frame 1 is primary). Manual selection disabled | |
| 0 1 0 0 | Stereo mode (channel 1 is left). Manual selection disabled | |
| 0 1 0 1 | Reserved for user-defined applications | |
| 0 1 1 0 | Reserved for user-defined applications | |
| 1 1 1 1 | Vector to Byte 3. Reserved for future use | |
| All other states are reserved | ||
| g Bits 4-7 | Encoded user bits management | |
| bit | 4 5 6 7 | |
| 0 0 0 0 | Default mode. No information indicated | |
| 0 0 0 1 | 192-bit block structure. Preamble Z indicates the start of the block | |
| 0 0 1 0 | Reserved for future use | |
| 0 0 1 1 | User defined use | |
| All other states are reserved | ||
All other states are reserved
Byte 2
| h Bits 0-2 | Encoded use of auxiliary sample bits | |
| bit | 0 1 2 | |
| 0 0 0 | Maximum audio sample is 20 bits (default). Use of aux sample not defined | |
| 0 0 1 | Maximum audio sample is 24 bits. Aux sample bits used for audio data | |
| 0 1 0 | Maximum audio sample is 20 bits. Aux sample bits used to carry voice quality (talkback) signal | |
| 0 1 1 | Reserved for future use | |
| i Bits 3-5 | Encoded audio sample word length | |
| bit | 3 4 5 | Audio sample wordlength Audio sample wordlength |
| if maximum wordlength is if maximum wordlength is | ||
| 24 bits as indicated in bits 20 bits as indicated in bits | ||
| 0-2 above 0-2 above | ||
| 0 0 0 | Not defined (Default) Not defined (Default) | |
| 0 0 1 | 23 bits 19 bits | |
| 0 1 0 | 22 bits 18 bits | |
| 0 1 1 | 21 bits 17 bits | |
| 1 0 0 | 20 bits 16 bits | |
| 1 0 1 | 24 bits 20 bits | |
| All other states are reserved | ||
| r Bits 6-7 | These are reserved for future use | |
Byte 3
| j Bits 0-7 | Vectored target byte from byte 1. Reserved for future use and currently set at logical 0 |
Byte 4
| k Bits 0-1 | Digital audio reference signal (per AES11) |
| bit 0 1 | |
| 0 0 | Not a reference signal (Default) |
| 0 1 | Grade 1 reference signal |
| 1 0 | Grade 2 reference signal |
| 1 1 | Reserved for future use |
| r Bits 2-7 | Reserved for future use and currently set at logical 0 |
| r Bits 0-7 | Reserved for future use and currently set at logical 0 |
Bytes 6-9
| Alphanumeric channel origin data. First character in message is byte 8 | |
| Bits 0-7 (each byte) | 7-bit ISO 646 characters with no parity bit. LSBs are transmitted first, with logical 0 in bit 7. Non-printed control characters (&01 to &1F and &7F) are not permitted |
Bytes 10-13
| Alphanumeric channel destination data. 1st character in message is byte 10 | |
| Bits 0-7 (each byte) | 7-bit ISO 646 characters with no parity bit. LSBs are transmitted first, with logic 0 in bit 7. Non-printed control characters (&01 to &1F &7F) are not permitted |
Bytes 14-17
| Local sample address code (32-bit binary). Value is of 1st sample of current block | |
| Bits 0-7 (each byte) | LSBs are transmitted first |
Bytes 18-21
| Time-of-day sample address code (32-bit binary). Value is of 1st sample of current block. | |
| Bits 0-7 (each byte) | LSBs are transmitted first |
Byte 22
| Channel Status Information reliability flags. If information is reliable, the appropriate bit is set to logical 0; if unreliable, it is set to logical 1 | |
| Bits 0-3 | Reserved and currently set to logical 0 |
| Bit 4 | Refers to bytes 0 to 5 |
| Bit 5 | Refers to bytes 6 to 13 |
| Bit 6 | Refers to bytes 14 to 17 |
| Bit 7 | Refers to bytes 18 to 21 |
Byte 23
Cyclic redundancy check character
Generating polynomial is:
G(x) = x8 + x4 + x3 + x2 + 1
LSB is transmitted first.
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