Texas Instruments DEM-PCM2912A EVM manual QuickTime Audio Recording Controls

Basic Operating Set-Up—Mac OS www.ti.com

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.

3.3.3 Sampling Frequency

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 3-16shows.

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 SBAU141–January 2009

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