audio.cpp

void Audio::initI2SDac() {
    adc1_config_channel_atten(I2S_ADC_CHANNEL, ADC_ATTEN_11db);
    i2s_config_t i2s_config = {
        .mode = static_cast<i2s_mode_t>(I2S_MODE_MASTER | I2S_MODE_RX |
                                        I2S_MODE_ADC_BUILT_IN),
        .sample_rate = I2S_SAMPLE_RATE,
        .bits_per_sample = static_cast<i2s_bits_per_sample_t>(I2S_SAMPLE_BITS),
        .channel_format = static_cast<i2s_channel_fmt_t>(I2S_FORMAT),
        .communication_format =
            static_cast<i2s_comm_format_t>(I2S_COMM_FORMAT_I2S_MSB),
        .intr_alloc_flags = 0,
        .dma_buf_count = 2,
        .dma_buf_len = SAMPLES,
        .use_apll = false,
        .tx_desc_auto_clear = false,
        .fixed_mclk = 0};
    i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
    i2s_set_adc_mode(I2S_ADC_UNIT, I2S_ADC_CHANNEL);
}

void Audio::audioTask() {
    size_t bytes_read;
    uint32_t dac_value = 0;
    int fftFrames = 0;
    int chain = 0;
    bool clipping = false;

    char* i2s_read_buff = (char*)calloc(SAMPLE_BYTES, sizeof(char));
    i2s_adc_enable(I2S_NUM);
    i2s_read(I2S_NUM, (void*)i2s_read_buff, SAMPLE_BYTES, &bytes_read, 2);

    while (1) {
        // read data from I2S bus, in this case, from ADC.
        i2s_read(I2S_NUM, (void*)i2s_read_buff, SAMPLE_BYTES, &bytes_read, 2);

        if (bytes_read == SAMPLE_BYTES) {
            int clips = 0;
            for (size_t i = 0; i < bytes_read / 2; i++) {
                dac_value =
                    ((((uint16_t)(i2s_read_buff[i * 2 + 1] & 0xf) << 8) |
                      ((i2s_read_buff[i * 2]))));
                if (dac_value < 2 || dac_value > 4094) {
                    clips++;
                }
                vReal[chain][i] = ((float)dac_value - MIDPOINT) / DIVISOR;
                vImag[chain][i] = 0;
            }
            chain = (chain + 1) % SAMPLE_CHAIN_NUM;

            if (clips > SAMPLES / 8) {
                audioClipping = true;
                clipping = true;
            } else {
                audioClipping = false;
            }

            // Build sample chain from all chunks
            for (size_t i = 0; i < SAMPLE_CHAIN_NUM; i++) {
                int chainNum = (chain + i) % SAMPLE_CHAIN_NUM;
                std::copy_n(vReal[chainNum], SAMPLES, vRealChain + i * SAMPLES);
                std::copy_n(vImag[chainNum], SAMPLES, vImagChain + i * SAMPLES);
            }

            arduinoFFT fft(vRealChain, vImagChain, TOTAL_CHAIN,
                           I2S_SAMPLE_RATE);

            fft.Windowing(FFT_WIN_TYP_BLACKMAN, FFT_FORWARD);
            fft.Compute(FFT_FORWARD);
            fft.ComplexToMagnitude();

            for (size_t i = 0; i < FFT_BUCKETS; i++) {
                if (vRealChain[i] > vMax[i]) {
                    vMax[i] = vRealChain[i];
                }
                vRealChain[i] =
                    (vRealChain[i] - noiseFloor[i]) / (vMax[i] - noiseFloor[i]);
            }

            for (size_t i = 0; i < bands.size(); i++) {
                bands[i]->update(vRealChain);
            }
        } else {
            ESP_LOGE(tagAudio, "DIDN'T GET ALL SAMPLES!!!");
        }

        vTaskDelay(0);
    }
    i2s_adc_disable(I2S_NUM);
    free(i2s_read_buff);
    i2s_read_buff = NULL;

    vTaskDelete(NULL);
}