CM6533,CM6533N,CM6533X1,CM6533DH
USB Audio Chip
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Rev.1.7
Copyright© C-Media Electronics Inc.
Coding format: biphase mark except the headers (preambles), for sync purposes
Bandwidth occupation: 100kHz up to 6Mhz (no DC)
Signal bitrate as following table:
Sampling Rate (KHz) SPDIF Bit Rate (MHz, 64*Fs)
96
6.144
88.2
5.6448
48
3.072
44.1
2.8224
1 0 1 1 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 1 0
1
0
0
1
1
0
1
0
0
1
0
0
Clock
Data Signal
Biphase Mark
Signal
Figure -17 Biphase Mark signal of SPDIF
Preamble cell-order
cell-order
(last cell "0")
(last cell "1")
------------------------------------------------------
"B"
11101000
00010111
"M"
11100010
00011101
"W"
11100100
00011011
Preamble “B”:
Marks a word containing data for channel A (left) at the start of the data-block.
Preamble “M”:
Marks a word with data for channel A that is not at the start of the data-block.
Preamble “W”:
Marks a word containing data for channel B (right, for stereo). When using more than 2 channels, this could also be
any other channel (except for A).
The number of subframes that are used depends on the number of channels that is transmitted. A CD-player uses
Channels A and B (left/right) and so each frame contains two subframes. A block contains 192 frames and starts with
a preamble "B":
