Texas Instruments DEM-PCM2912 EVM, User Manual, Page: 30 / 43

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3.3.3 Sampling Frequency
Basic Operating Set-Up—Mac OS
To set the microphone sidetone:
The volume setting of the microphone sidetone is controlled by the individual application software on
the Mac. For example,
Audio Recording using QuickTime
®
(as shown in Figure 3-15 ) sets the
microphone volume for sidetone from –76dB to 0dB.
Figure 3-15. QuickTime Audio Recording Controls
After this process is complete, the system volume setting for each component is maintained even if EVM
is plugged in/out.
Under the Mac OS X operating system, it is necessary to select a specific sampling frequency because
the sampling frequency cannot be changed on nearly all application software.
To set the DAC sampling frequency:
1. Open the Audio MIDI Settings options ( Application
→
Utility
→
Set Audio MIDI ), as illustrated in
Figure 3-16 .
2. Select the Audio Input tab in the Set Audio MIDI options group, as Figure 3-16 shows.
3. Select the desired DAC sampling frequency from seven options: 8 kHz, 11.025 kHz,16 kHz, 22.5 kHz,
32 kHz, 44.1 kHz, and 48 kHz.
To set the ADC sampling frequency:
1. Open the Audio MIDI Settings options ( Application
→
Utility
→
Set Audio MIDI ), as illustrated in
Figure 3-16 .
2. Select the Audio Output tab in the Set Audio MIDI options group, as shown in Figure 3-16 .
3. Select the desired ADC sampling frequency from seven options: 8 kHz, 11.025 kHz,16 kHz, 22.5 kHz,
32 kHz, 44.1 kHz, and 48 kHz.
30 Set-Up Guide SBAU132 – March 2008
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