STV82X6 datasheet(17/95 Pages) STMICROELECTRONICS

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STV82x6

Audio Processor Block

required, it complements the dedicated prescaler for FM, NICAM or SCART sources. The internal

level can be measured using the peak detector.

The SVC can be used either in the Loudspeaker or Headphone path (but not both simultaneously).

When used in the Headphone path, the SVC prevents the sound level from becoming suddenly too

strong, causing ear damage. The SVC is configured in registers SVC_SEL and SVC_CTRL.

3.3

ST WideSurround

STV82x6 offers three preset ST WideSurround effects on the Loudspeaker path:

●

Music, a concert hall effect

●

Movie, for films on TV

●

Simulated Stereo, which generates a pseudo-stereo effect from mono source

“ST WideSurround” is an extension of the conventional stereo concept which improves the spatial

characteristics of the sound. This could be done simply by adding more speakers and coding more

channels into the source signal as is done in the cinema, but this approach is too costly for normal

home use. The ST WideSurround system exploits a method of phase shifting to achieve a similar

result using only two speakers. It restores spatiality by adding artificial phase differences.

The Surround/Pseudo-stereo mode is automatically selected by the Automatic Standard

Recognition System (AUTOSTD) depending on the detected stereo or mono source. By default,

“Movie” is selected for Surround mode. This value may be changed to “Music” by the STS_MODE

bit in the LS_SRD_CTRL register.

Additional user controls are provided to better adapt the spatial effect to the source. The ST

WideSurround Gain (LS_STS_GAIN) and ST WideSurround Frequency (LS_STS_FREQ) registers

can be used to enhance music predominance in Music mode and theater effect + voice

predominancy in Movie mode.

3.4

5-Band Audio Equalizer

The Loudspeaker audio spectrum is split into 5 frequency bands and the gain of each of them can

be adjusted within a range from -12 dB to +12 dB in steps of 1 dB. The Audio Equalizer may be

used to pre-define frequency band enhancement features dedicated to various kinds of music or to

attenuate frequency resonances of loudspeakers or the listening environment. The Equalizer is

enabled by the EQ_ON bit in the LS_EQ_CTRL register. The Bass, Medium and Treble values are

programmed in registers LS_EQ_BAND[1:5].

3.5

Bass/Treble Control

The gain of bass and treble frequency bands for the headphone can be also tuned within a range

from -12 dB to +12 dB in steps of 1 dB. It may be used to pre-define frequency band enhancement

Figure 9: Equalizer

f1=100Hz f2=330Hz

f3=1KHz

f4=3.3KHz f5=6.6KHz

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