Texas Instruments PCM5122 Evaluation Module PCM5122EVM-U PCM5122EVM-U Datenbogen
Produktcode
PCM5122EVM-U
SLAS759A – AUGUST 2012 – REVISED SEPTEMBER 2012
Table 33. Biquad Filter Coefficients (continued)
Filter
Channel
Coefficient
Register
N0
C65 (Pg 46, Reg 28, 29, 30, 31)
N1
C66 (Pg 46, Reg 32, 33, 34, 35)
Lch,
BIQUAD (7) - 2 BIQUAD (8) - 2
N2
C67 (Pg 46, Reg 36, 37, 38, 39)
Rch
D1
C68 (Pg 46, Reg 40, 41, 42, 43)
D2
C69 (Pg 46, Reg 44, 45, 46, 47)
Dynamic Range Compression
Dynamic range compression (DRC) improves the overall listening experience. Typical music signals are
characterized by crest factors (the ratio of peak signal power to average signal power) of 12dB or more. To avoid
audible distortion due to clipping of peak signals, the gain of the DAC channel must be adjusted so as not to
cause hard clipping. As a result, the low applied gain during nominal periods causes the perception that the
signal is not loud enough. To overcome this problem, the DRC in the PCM514x continuously monitors the output
of the DAC Digital Volume control to detect its power level with respect to 0dB full-scale. When the power level is
low, the DRC increases the input signal gain to make it sound louder, and reduces the gain during peaks to
avoid hard clipping. The DRC enables louder audio during nominal periods with a clearer, more pleasant
listening experience.
characterized by crest factors (the ratio of peak signal power to average signal power) of 12dB or more. To avoid
audible distortion due to clipping of peak signals, the gain of the DAC channel must be adjusted so as not to
cause hard clipping. As a result, the low applied gain during nominal periods causes the perception that the
signal is not loud enough. To overcome this problem, the DRC in the PCM514x continuously monitors the output
of the DAC Digital Volume control to detect its power level with respect to 0dB full-scale. When the power level is
low, the DRC increases the input signal gain to make it sound louder, and reduces the gain during peaks to
avoid hard clipping. The DRC enables louder audio during nominal periods with a clearer, more pleasant
listening experience.
The 3-band DRC function applies DRC to 3 different mono/stereo signals with 3 different time constants. The
same DRC curve is applied on all the signals, enabling a multi-band DRC solution. The underlying DRC
algorithm is the same as that available with the DRC component in PurePath Studio. In this instance, the DRC
gain acts on each signal in time-multiplexed order, for example, 1-2-3, 1-2-3, 1-2-3.
same DRC curve is applied on all the signals, enabling a multi-band DRC solution. The underlying DRC
algorithm is the same as that available with the DRC component in PurePath Studio. In this instance, the DRC
gain acts on each signal in time-multiplexed order, for example, 1-2-3, 1-2-3, 1-2-3.
Table 34. DRC Coefficients
Coefficient
Register
Description
DRC_MB_1_DRC_1_DRCAE
C70 (Pg 46, Reg 48, 49, 50, 51)
DRC_MB_1_DRC_1_DRC1AE
C71 (Pg 46, Reg 52, 53, 54, 55)
DRC_MB_1_DRC_1_DRCAA
C72 (Pg 46, Reg 56, 57, 58, 59)
DRC_MB_1_DRC_1_DRC1AA
C73 (Pg 46, Reg 60, 61, 62, 63)
DRC_MB_1_DRC_1_DRCAD
C74 (Pg 46, Reg 64, 65, 66, 67)
DRC_MB_1_DRC_1_DRC1AD
C75 (Pg 46, Reg 68, 69, 70, 71)
DRC_MB_1_DRC_2_DRCAE
C76 (Pg 46, Reg 72, 73, 74, 75)
DRC_MB_1_DRC_2_DRC1AE
C77 (Pg 46, Reg 76, 77, 78, 79)
DRC_MB_1_DRC_2_DRCAA
C78 (Pg 46, Reg 80, 81, 82, 83)
DRC_MB_1_DRC_2_DRC1AA
C79 (Pg 46, Reg 84, 85, 86, 87)
DRC_MB_1_DRC_2_DRCAD
C80 (Pg 46, Reg 88, 89, 90, 91)
DRC_MB_1_DRC_2_DRC1AD
C81 (Pg 46, Reg 92, 93, 94, 95)
DRC_MB_1_DRC_3_DRCAE
C82 (Pg 46, Reg 96, 97, 98, 99)
DRC_MB_1_DRC_3_DRC1AE
C83 (Pg 46, Reg 100, 101, 102, 103)
DRC_MB_1_DRC_3_DRCAA
C84 (Pg 46, Reg 104, 105, 106, 107)
DRC_MB_1_DRC_3_DRC1AA
C85 (Pg 46, Reg 108, 109, 119, 111)
DRC_MB_1_DRC_3_DRCAD
C86 (Pg 46, Reg 112, 113, 114, 115)
DRC_MB_1_DRC_3_DRC1AD
C87 (Pg 46, Reg 116, 117, 118, 119)
DRC_MB_1_DRC_DRCK0
C88 (Pg 46, Reg 120, 121, 122, 123)
DRC_MB_1_DRC_DRCK1
C89 (Pg 46, Reg 124, 125, 126, 127)
DRC_MB_1_DRC_DRCK2
C90 (Pg 47, Reg 8, 9, 10, 11)
DRC_MB_1_DRC_DRCMT1
C91 (Pg 47, Reg 12, 13, 14, 15)
DRC_MB_1_DRC_DRCMT2
C92 (Pg 47, Reg 16, 17, 18, 19)
DRC_MB_1_DRC_DRCOFF1
C93 (Pg 47, Reg 20, 21, 22, 23)
DRC_MB_1_DRC_DRCOFF2
C94 (Pg 47, Reg 24, 25, 26, 27)
DRC_MB_1_MinusOne_Q22
C95 (Pg 47, Reg 28, 29, 30, 31)
58
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