WM8948ECSSLASHR datasheet(36/189 Pages) WOLFSON

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WM8948

Production Data

PD, May 2011, Rev 4.1

3D SURROUND

The 3D-stereo surround effect is part of the SE1 block. This function uses time delays and controlled

cross-talk mechanisms to adjust the depth or width of the stereo audio. The 3D-stereo surround

effect includes programmable high-pass or low-pass filtering to limit the 3D effect to specific

frequency bands if required. The structure of the 3D surround processing is illustrated in Figure 15.

Figure 15 3D Surround Processing

The 3D surround depth is programmable; the default setting is OFF. The 3D surround processing

can also be configured to create a mono mix of the Left and Right channels.

The 3D enhancement is enabled on the left and right channels using the SE1_3D_L_ENA and

SE1_3D_R_ENA register bits defined in Table 13. These bits can be enabled independently of each

other. For the derivation of the other associated registers, refer to the configuration tools supplied

with the WM8948 Evaluation Kit.

5-NOTCH FILTER

The 5-notch filter is part of the SE1 block. This function allows up to 5 programmable frequency

bands to be attenuated. The frequency and width of each notch is configurable; the depth of the

attenuation may also be adjusted. The default setting is bypass (OFF). The notch filters may be

enabled on the left and right channels using the SE1_NOTCH_L_ENA and SE1_NOTCH_R_ENA

configuration tools supplied with the WM8948 Evaluation Kit. Note that, although the 5-notch filter

can be enabled on the left/right channels independently, the parameters that define the notch filters

apply equally to the left and right channels, when enabled.

Typical applications for the notch filters are filtering of fixed-frequency noise or resonances; these

might arise from a motor (eg. DSC zoom lens motor) or from characteristics of the application

housing. Example plots of the Notch filter response are shown in Figure 16.

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