Audio Codec '97

AC ‘97 Component Specification Revision 2.3 Rev 1.0
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• SRC mechanisms
• slot mapping configurations
• internal gains and phase inversions
5.4.2.1 Default Slot to DAC Mappings for Secondary Audio Codecs
The AMAP bit, D9 in the Extended Audio ID Register (Register 28h), indicates whether or not the audio Codec
supports AC ‘97 compliant default AC-link slot to audio DAC mappings. AMAP = 1 in D9 indicates that the
default (following cold or warm reset) Codec slot to DAC mappings (configured via hardwiring, strap pin(s), or
other methods) conform to Table 13.
All Audio Codecs must implement the following power-up default AC-link to DAC mapping behavior:
A Secondary audio Codec by default always assigns its DACs to AC-link slots in a fixed sequence {L, R, LS, RS, C,
LFE to 3, 4, 7, 8, 6, 9} with the Codec ID indicating where in the sequence to begin (see table below). Default
S/PDIF assignment always begins with the first slots not assigned to DACs.
Optional baseline (see Section 5.8.1) or vendor specific slot to DAC re-mapping capability is also recommended.
Default AC-link to DAC mapping by Codec ID
Function Codec ID 3&4 7&8 6&9 10&11
2-ch Primary 00 L&R − − −
2-ch Secondary* 01 − Surr − −
+2-ch Secondary 10 − Surr − −
+2-ch Secondary 11 − − C/LFE −
2-ch Primary with S/PDIF 00 L&R S/PDIF − −
+2-ch Secondary with S/PDIF* 01 − Surr S/PDIF −
+2-ch Secondary with S/PDIF 10 − Surr S/PDIF −
+2-ch Secondary with S/PDIF 11 − − C/LFE S/PDIF
4-ch Primary 00 L&R Surr − −
+4-ch Secondary* 01 − Surr C/LFE −
+4-ch Secondary 10 − Surr C/LFE −
+4-ch Secondary 11 − - C/LFE −
4-ch Primary with S/PDIF 00 L&R Surr S/PDIF −
+4-ch Secondary with S/PDIF* 01 − Surr C/LFE S/PDIF
+4-ch Secondary with S/PDIF 10 − Surr C/LFE S/PDIF
+4-ch Secondary with S/PDIF 11 − - C/LFE S/PDIF
Codec ID is available to the Controller via Register 28h, bits D15 & D14.
*These new defaults for a Secondary Codec configured as ID 01 replace AC ‘97 2.1 AMAP recommendations for dock Codec
functionality. Since docking is by nature proprietary, the vendor specific support should be used to reconfigure Codec 01 as
necessary. All other mappings are compatible with AC ‘97 2.1 AMAP.
Table 13. Default Slot to DAC Mappings Based on Codec ID
5.4.2.2
DAC Management across Multiple Audio Codecs
The use of multiple AC ‘97 Codecs to achieve multi-channel audio requires that the driver writer knows where to
access DAC Ready status and Powerdown control for all channels. In monolithic multi-channel Codecs, for Front
L&R DACs bit D1 in Register 26h indicates Ready and bit D9 controls Powerdown. For Center, Surround L&R,
and LFE channels, bits D6, D7, and D8 in Register 2Ah indicates DAC Ready respectively. Bits D11, D12, and