Cirrus Logic AN22 - Manual (Page 7)

AN22
AN22REV2 7
Currently the standards committees are trying to
define a minimum implementation as well as levels
of implementation of channel status data.
A scheme for providing copy protection is also cur-
rently being developed. It includes knowing the
category code and then utilizing the Copy and L
bits to determine if a copy should be allowed. Dig-
ital processing of data should pass through the copy
and L bits as defined by their particular category
code. If mixing inputs, the highest level of protec-
tion of any one of the sources should be passed
through. If the copy bit indicates no copy protec-
tion (copy = 1), then multiple copies can be made.
If recording audio data to tape or disk, and any
BYTE 0
bit 0 PRO = 0 (consumer)
0 Consumer use of channel status block
1 Professional use of channel status block
bit 1 Audio
0
1 Digital Audio
Non-Audio
bits 2 Copy / Copyright
0
1 Copy inhibited / copyright asserted
Copy permitted / copyright not asserted
bits 3 4 5 Pre-emphasis - if bit 1 is 0 (dig. audio)
0 0 0 None - 2 channel audio
1
0
1
X
0
1
1
X
0
0
0
1 50/15
µ
s - 2 channel audio
Reserved - 2 channel audio
Reserved - 2 channel audio
Reserved - 4 channel audio
bits 3 4 5 if bit 1 is 1 (non-audio)
0 0 0 Digital data
X X X All other states of bits 3-5 are reserved
bits 6 6 Mode
0 0 Mode 0 (defines bytes 1-3)
X X All other states of bits 6-7 are reserved
BYTE 1 - Category Code 001
bits 3 4 5 6 Broadcast reception of digital audio
*
0 0 0 0 Japan
* 0 0 1 1 United States
* 1 0 0 0 Europe
* 0 0 0 1 Electronic software delivery
X X X X All other states are reserved
BYTE 1 - Category Code 100
bits 3 4 5 6 Laser Optical
0 0 0 0 CD - compatible with IEC-908
* 1 0 0 0 CD - not comp. with IEC-908
(magneto-optical)
X X X X All other states are reserved
BYTE 1
bits 0 1 2 3 4 5 6 Category Code
0 0 0 0 0 0 0 General
* 0 0 1 Experimental
X X X Reserved
* 0 0 0 1 X X X Solid state memory
* 0 0 1 X X X X Broadcast recep. of digital audio
0 1 0 X X X X Digital/digital converters
* 0 1 1 0 0 X X A/D converters w/o copyright
* 1 X X A/D converters w/ copyright
(using Copy and L bits)
* 0 1 1 1 X X X Broadcast recep. of digital audio
1 0 0 X X X X Laser-optical
* 1 0 1 X X X X Musical Instruments, mics, etc.
1 1 0 X X X X Magnetic tape or disk
1 1 1 X X X X Reserved
bit 7 L: Generation Status.
Only category codes:001XXXX,
0111XXX,100XXXX
* 0 Original/Commercially pre-recorded data
* 1 No indication or 1st generation or higher
All other category codes
* 0 No indication or 1st generation or higher
* 1 Original/Commercially pre-recorded data
The subgroups under the category code groups listed above
are described in tables below. Those not listed are reserved.
The Copy and L bits form a copy protection scheme for
original works. Further explanations can be found in the
proposed amendment (TC84) to IEC-958.
BYTE 1 - Category Code 010
bits 3 4 5 6 Digital/digital conv. & signal processing
0 0 0 0 PCM encoder/decoder
* 0 0 1 0 Digital sound sampler
* 0 1 0 0 Digital signal mixer
* 1 1 0 0 Sample-rate converter
X X X X All other states are reserved
Table 4. Consumer Channel Status Bytes 0 and 1.