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static void init_i2s_dac()
{

    i2s_config_t i2s_config = {
        .mode = I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN,          // Only TX
        .sample_rate = 44100,
        .bits_per_sample = 8,                                                   // Only 8-bit DAC support
        .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,                           // 2-channels
        .communication_format = I2S_COMM_FORMAT_I2S_MSB,
        .dma_buf_count = 14,                                                    // number of buffers, 128 max.
        .dma_buf_len = 32*2,                                                    // size of each buffer
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1                                // Interrupt level 1
    };

    i2s_pin_config_t pin_config = {
        .bck_io_num = 26,
        .ws_io_num = 25,
        .data_out_num = 22,
        .data_in_num = I2S_PIN_NO_CHANGE                                          // Not used
    };

    i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
    i2s_set_pin(I2S_NUM, &pin_config);
}

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static int convert_sample(short s) {

    // convert 16bit to 8bit and duplicate mono sample to both channels
    char eightBit = s >> 8;
    short samp = eightBit;
    samp = (samp) & 0xff;
    samp = (samp << 8) | samp;
    return samp;
}

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static int convert_sample(short s) {

    return s & 0xff00 | s >> 8;
  
}

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return (unsigned short) s & 0xff00 | (unsigned short) s >> 8;