59.1. SMIX

59.1.1. Overview

SMIX example project demonstrates the mixing function of audio stream. In the example project, two different sampling rates of audio are converted into the same sampling rate and mixed for playback.

59.1.2. Project Configuration

• In the file CMakeLists.txt, set a matched audio codec type according to the development board schematic，e.g. “set(CONFIG_CODEC “wm8960”)”

59.1.3. Board Setting

• Connect headphone to the headphone interface on the audio codec chip to play audio data

59.1.4. Known Issue

• When using the headphone interface of Codec to play audio on some development boards, there may be crosstalk. For example, when playing mono audio through the left channel of the headphone, weak sound can be heard on the right channel headphone.

59.1.5. Running the example

When the project runs correctly, the serial port terminal will output the following information and the headphone will play the sound:

Sound mixer example
mixer play one sound
input sound sample rate: 8000Hz
output sound sample rate: 48000Hz
mixer play one sound
input sound sample rate: 16000Hz
output sound sample rate: 48000Hz
mixer play two sound
input sound0 sample rate: 8000Hz
input sound1 sample rate: 16000Hz
output sound sample rate: 48000Hz