ak4683 AKM Semiconductor, Inc., ak4683 Datasheet - Page 57

• Manufacturer Part Number: ak4683
• Description: Asynchronous Multi-channel Audio Codec With Dir/t
• Manufacturer: AKM Semiconductor, Inc.

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The AK4683 has a Non-PCM steam auto-detection function. When the 32bit mode Non-PCM preamble based on Dolby
“AC-3 Data Stream in IEC60958 Interface” is detected, the AUTO bit goes “1”. The 96bit sync code consists of 0x0000,
0x0000, 0x0000, 0x0000, 0xF872 and 0x4E1F. Detection of this pattern will set the AUTO bit “1”. Once the AUTO bit
is set “1”, it will remain “1” until 4096 frames pass through the chip without additional sync pattern being detected.
When those preambles are detected, the burst preambles Pc and Pd that follow those sync codes are stored to registers.
The AK4683 also has the DTS-CD bitstream auto-detection function. When The AK4683 detects DTS-CD bitstreams,
DTSCD bit goes to “1”. When the next sync code does not come within 4096 flames, DTSCD bit goes to “0” until
when the AK4683 detects the stream again.
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MS0427-E-02
Non-PCM (AC-3, MPEG, etc.) and DTS-CD Bitstream Detection
Burst Preambles in non-PCM Bitstreams
Preamble word
Pa
Pb
Pc
Pd
Pa Pb Pc Pd
0
preamble
Length of field
16 bits
16 bits
16 bits
16 bits
3 4
Aux.
7 8
Figure 37. Data structure in IEC60958
Table 60. Burst preamble words
repetition time of the burst
11 12
sub-frame of IEC60958
Burst_payload
0
LSB
Contents
sync word 1
sync word 2
Burst info
Length code
- 57 -
16 bits of bitstream
stuffing
MSB V U C P
Value
0xF872
0x4E1F
see Table 61
Numbers of bits
27 28 29 30 31
15
[AK4683]
2007/04