#include <stdio.h>
#include <inttypes.h>
#include <sdkconfig.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include "esp_log.h"
#include "esp_dsp.h"
#include "bsp/esp-bsp.h"
#include <stdint.h>
#include <math.h>

Include dependency graph for external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c:

Macros
#define	BUFFER_SIZE (64)
#define	SAMPLE_RATE (16000)
#define	DEFAULT_VOLUME (100)

Typedefs
typedef enum audio_set	audio_set_t

Enumerations
enum	audio_set { AUDIO_VOLUME , AUDIO_BASS , AUDIO_TREBLE }

Functions
static void	btn_handler (void button_handle, void usr_data)
struct	__attribute__ ((packed))
static void	buttons_process_task (void *arg)
static void	audio_read_task (void *arg)
static void	audio_process_task (void *arg)
static void	convert_short2float (int16_t int16_data, float float_data, int len)
static void	convert_float2short (float float_data, int16_t int16_data, int len)
void	digitalLimiter (float input_signal, float output_signal, int signal_length, float threshold, float attack_value, float release_value, float *in_envelope)
void	app_main (void)

Variables
static const char *	TAG = "example"
static QueueHandle_t	audio_button_q = NULL
	dumb_wav_header_t
static esp_codec_dev_handle_t	spk_codec_dev = NULL
static FILE *	play_file = NULL
static const char	play_filename [] = BSP_SPIFFS_MOUNT_POINT"/16bit_mono_44_1_khz.wav"
static dumb_wav_header_t	wav_header
static audio_set_t	current_set = AUDIO_VOLUME
float	iir_coeffs_lpf [5]
float	iir_w_lpf [5] = {0, 0}
float	iir_coeffs_hpf [5]
float	iir_w_hpf [5] = {0, 0}
float	lpf_gain = 0
float	lpf_qFactor = 0.5
float	lpf_freq = 0.01
float	hpf_gain = 0
float	hpf_qFactor = 1
float	hpf_freq = 0.15
float	full_volume = 1
int	full_volume_db = -12
float	full_envelope = 0
float	processing_audio_buffer [(64)] = {0}
int16_t	triple_audio_buffer [3 *(64)] = {0}
int	audio_buffer_write_index = 0
int	audio_buffer_read_index = 0
static SemaphoreHandle_t	sync_read_task

Macro Definition Documentation

◆ BUFFER_SIZE

#define BUFFER_SIZE (64)

Definition at line 23 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

◆ DEFAULT_VOLUME

#define DEFAULT_VOLUME (100)

Definition at line 25 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

◆ SAMPLE_RATE

#define SAMPLE_RATE (16000)

Definition at line 24 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

Typedef Documentation

◆ audio_set_t

typedef enum audio_set audio_set_t

Enumeration Type Documentation

◆ audio_set

enum audio_set

Enumerator
AUDIO_VOLUME
AUDIO_BASS
AUDIO_TREBLE

Definition at line 50 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

                       {
    AUDIO_VOLUME,
    AUDIO_BASS,
    AUDIO_TREBLE,
} audio_set_t;

Function Documentation

◆ attribute()

struct __attribute__ ( (packed) )

Definition at line 31 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

{
    uint8_t ignore_0[22];
    uint16_t num_channels;
    uint32_t sample_rate;
    uint8_t ignore_1[6];
    uint16_t bits_per_sample;
    uint8_t ignore_2[4];
    uint32_t data_size;
    uint8_t data[];
} dumb_wav_header_t;

References audio_button_q, and button_pressed.

◆ app_main()

void app_main ( void )

Definition at line 365 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

{
    ESP_ERROR_CHECK(bsp_spiffs_mount());
 
    // Create FreeRTOS tasks and queues
    audio_button_q = xQueueCreate(10, sizeof(int));
    assert (audio_button_q != NULL);
 
    BaseType_t ret = xTaskCreate(audio_process_task, "audio_process_task", 4096, NULL, 6, NULL);
    assert(ret == pdPASS);
 
    // Init audio buttons
    button_handle_t btns[BSP_BUTTON_NUM];
    ESP_ERROR_CHECK(bsp_iot_button_create(btns, NULL, BSP_BUTTON_NUM));
    for (int i = 0; i < BSP_BUTTON_NUM; i++) {
        ESP_ERROR_CHECK(iot_button_register_cb(btns[i], BUTTON_PRESS_DOWN, btn_handler, (void *) i));
    }
}

References audio_button_q, audio_process_task(), and btn_handler().

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◆ audio_process_task()

void audio_process_task ( void * arg )

static

Definition at line 155 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

{
    // Init codeac and apply the initial volume to maximum
    spk_codec_dev = bsp_audio_codec_speaker_init();
    assert(spk_codec_dev);
    esp_codec_dev_set_out_vol(spk_codec_dev, DEFAULT_VOLUME);
 
    // Open file and het the WAV header to set up the sample frequency, amount of channels and resolution
    play_file = fopen(play_filename, "rb");
    if (play_file == NULL) {
        ESP_LOGW(TAG, "%s file does not exist!", play_filename);
    }
    // Read WAV header
    if (fread((void *)&wav_header, 1, sizeof(wav_header), play_file) != sizeof(wav_header)) {
        ESP_LOGW(TAG, "Error in reading file");
        return;
    }
 
    ESP_LOGI(TAG, "Number of channels: %" PRIu16 "", wav_header.num_channels);
    ESP_LOGI(TAG, "Bits per sample: %" PRIu16 "", wav_header.bits_per_sample);
    ESP_LOGI(TAG, "Sample rate: %" PRIu32 "", wav_header.sample_rate);
    ESP_LOGI(TAG, "Data size: %" PRIu32 "", wav_header.data_size);
    esp_codec_dev_sample_info_t fs = {
        .sample_rate = wav_header.sample_rate,
        .channel = wav_header.num_channels,
        .bits_per_sample = wav_header.bits_per_sample,
    };
    if (spk_codec_dev != NULL) {
        int result = esp_codec_dev_open(spk_codec_dev, &fs);
    }
    // Calculate initial volume value
    full_volume = exp10f((float)full_volume_db / 20);
    // Calculate initial state for LPF
    dsps_biquad_gen_lowShelf_f32(iir_coeffs_lpf, lpf_freq, lpf_gain, lpf_qFactor);
    // Calculate initial state for HPF
    dsps_biquad_gen_highShelf_f32(iir_coeffs_hpf, hpf_freq, hpf_gain, hpf_qFactor);
 
    BaseType_t ret = xTaskCreate(buttons_process_task, "buttons_process_task", 4096, NULL, 4, NULL);
    assert(ret == pdPASS);
 
    sync_read_task = xSemaphoreCreateCounting(1, 0);
 
    ret = xTaskCreate(audio_read_task, "audio_read_task", 4096, NULL, 7, NULL);
    assert(ret == pdPASS);
    vTaskDelay(1);
 
    ESP_LOGW(TAG, "To select volume/bass/treble please use the 'Set' button. And adjust the value with +/- buttons.");
 
    for (;;) {
        /* Get data from SPIFFS and send it to codec */
        int16_t *wav_bytes = &triple_audio_buffer[audio_buffer_write_index * BUFFER_SIZE];
        // Write samples to audio codec
        esp_codec_dev_write(spk_codec_dev, wav_bytes, BUFFER_SIZE * sizeof(int16_t));
        audio_buffer_write_index++;
        if (audio_buffer_write_index >= 3) {
            audio_buffer_write_index = 0;
        }
        // Check the triple buffer overflow
        if (audio_buffer_write_index == audio_buffer_read_index) {
            // Call delay to switch the task to fill the buffer
            vTaskDelay(1);
            // Check and indicate overflow status
            if (audio_buffer_write_index == audio_buffer_read_index) {
                ESP_LOGW(TAG, "Audio buffer overflow!");
            }
        }
        // Generate synt event to read task:
        xSemaphoreGive(sync_read_task);
    }
}

References audio_buffer_read_index, audio_buffer_write_index, audio_read_task(), BUFFER_SIZE, buttons_process_task(), DEFAULT_VOLUME, dsps_biquad_gen_highShelf_f32(), dsps_biquad_gen_lowShelf_f32(), full_volume, full_volume_db, hpf_freq, hpf_gain, hpf_qFactor, iir_coeffs_hpf, iir_coeffs_lpf, lpf_freq, lpf_gain, lpf_qFactor, play_file, play_filename, spk_codec_dev, sync_read_task, TAG, triple_audio_buffer, and wav_header.

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◆ audio_read_task()

void audio_read_task ( void * arg )

static

Definition at line 229 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

{
    while (1) {
        // Wait the sync semaphore
        if (xSemaphoreTake(sync_read_task, 100)) {
            // Get the pointer to the current audio buffer
            int16_t *wav_buffer = &triple_audio_buffer[audio_buffer_read_index * BUFFER_SIZE];
            // Read the data from the file
            uint32_t bytes_read_from_spiffs = fread(wav_buffer, sizeof(int16_t), BUFFER_SIZE, play_file);
            // Convert input samples from int16 to float for processing
            convert_short2float((int16_t *)wav_buffer, processing_audio_buffer, BUFFER_SIZE);
            // Apply bass
            dsps_biquad_f32(processing_audio_buffer, processing_audio_buffer, BUFFER_SIZE, iir_coeffs_lpf, iir_w_lpf);
            // Apply treble
            dsps_biquad_f32(processing_audio_buffer, processing_audio_buffer, BUFFER_SIZE, iir_coeffs_hpf, iir_w_hpf);
            // Apply voluve
            dsps_mulc_f32_ansi(processing_audio_buffer, processing_audio_buffer, BUFFER_SIZE, full_volume, 1, 1);
            // Apply limiter
            digitalLimiter(processing_audio_buffer, processing_audio_buffer, BUFFER_SIZE, 0.5, 0.5, 0.0001, &full_envelope);
            // Convert from float to int16 for audio codec
            convert_float2short(processing_audio_buffer, (int16_t *)wav_buffer, BUFFER_SIZE);
 
            if (bytes_read_from_spiffs != BUFFER_SIZE) {
                // Rewind the file and read the WAV header
                rewind(play_file);
                fread((void *)&wav_header, 1, sizeof(wav_header), play_file);
                // Read data to the audio buffer
                bytes_read_from_spiffs = fread(wav_buffer, sizeof(int16_t), BUFFER_SIZE, play_file);
            }
            audio_buffer_read_index++;
            if (audio_buffer_read_index >= 3) {
                audio_buffer_read_index = 0;
            }
        } else {
            // Error in case of timeout
            ESP_LOGE(TAG, "Audio timeout!");
        }
    }
}

References audio_buffer_read_index, BUFFER_SIZE, convert_float2short(), convert_short2float(), digitalLimiter(), dsps_biquad_f32, dsps_mulc_f32_ansi(), full_envelope, full_volume, iir_coeffs_hpf, iir_coeffs_lpf, iir_w_hpf, iir_w_lpf, play_file, processing_audio_buffer, sync_read_task, TAG, triple_audio_buffer, and wav_header.

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◆ btn_handler()

void btn_handler	(	void *	button_handle,
		void *	usr_data )

static

Definition at line 31 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

{
    int button_pressed = (int)usr_data;
    xQueueSend(audio_button_q, &button_pressed, 0);
}

◆ buttons_process_task()

void buttons_process_task ( void * arg )

static

Definition at line 269 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

{
    while (1) {
        int btn_index = 0;
        if (xQueueReceive(audio_button_q, &btn_index, portMAX_DELAY) == pdTRUE) {
            switch (btn_index) {
            case BSP_BUTTON_SET: {
                current_set += 1;
                if (current_set > 2) {
                    current_set = AUDIO_VOLUME;
                }
                switch (current_set) {
                case AUDIO_VOLUME:
                    ESP_LOGW(TAG, "Select volume");
                    break;
                case AUDIO_BASS:
                    ESP_LOGW(TAG, "Select bass");
                    break;
                case AUDIO_TREBLE:
                    ESP_LOGW(TAG, "Select treble");
                    break;
                default:
                    break;
                }
                break;
            }
            case BSP_BUTTON_VOLDOWN: {
                switch (current_set) {
                case AUDIO_VOLUME:
                    full_volume_db -= 3;
                    if (full_volume_db < -36) {
                        full_volume_db = -36;
                    }
                    full_volume = exp10f((float)full_volume_db / 20);
                    ESP_LOGI(TAG, "Volume Down: %i dB", full_volume_db);
                    break;
                case AUDIO_BASS:
                    lpf_gain -= 1;
                    if (lpf_gain < -12) {
                        lpf_gain = -12;
                    }
                    ESP_LOGI(TAG, "Bass Down: %i", (int)lpf_gain);
                    dsps_biquad_gen_lowShelf_f32(iir_coeffs_lpf, lpf_freq, lpf_gain, lpf_qFactor);
                    break;
                case AUDIO_TREBLE:
                    hpf_gain -= 1;
                    if (hpf_gain < -12) {
                        hpf_gain = -12;
                    }
                    ESP_LOGI(TAG, "Treble Down: %i", (int)hpf_gain);
                    dsps_biquad_gen_highShelf_f32(iir_coeffs_hpf, hpf_freq, hpf_gain, hpf_qFactor);
                    break;
                default:
                    break;
                }
                break;
            }
            case BSP_BUTTON_VOLUP: {
                switch (current_set) {
                case AUDIO_VOLUME:
                    full_volume_db += 3;
                    if (full_volume_db > 0) {
                        full_volume_db = 0;
                    }
                    full_volume = exp10f((float)full_volume_db / 20);
                    ESP_LOGI(TAG, "Volume Up: %i dB", full_volume_db);
                    break;
                case AUDIO_BASS:
                    lpf_gain += 1;
                    if (lpf_gain > 12) {
                        lpf_gain = 12;
                    }
                    ESP_LOGI(TAG, "Bass Up: %i", (int)lpf_gain);
                    dsps_biquad_gen_lowShelf_f32(iir_coeffs_lpf, lpf_freq, lpf_gain, lpf_qFactor);
                    break;
                case AUDIO_TREBLE:
                    hpf_gain += 1;
                    if (hpf_gain > 12) {
                        hpf_gain = 12;
                    }
                    ESP_LOGI(TAG, "Treble Up: %i", (int)hpf_gain);
                    dsps_biquad_gen_highShelf_f32(iir_coeffs_hpf, hpf_freq, hpf_gain, hpf_qFactor);
                    break;
                default:
                    break;
                }
                break;
            }
            default:
                ESP_LOGI(TAG, "No function for this button");
                break;
            }
        }
    }
}

References AUDIO_BASS, audio_button_q, AUDIO_TREBLE, AUDIO_VOLUME, current_set, dsps_biquad_gen_highShelf_f32(), dsps_biquad_gen_lowShelf_f32(), full_volume, full_volume_db, hpf_freq, hpf_gain, hpf_qFactor, iir_coeffs_hpf, iir_coeffs_lpf, lpf_freq, lpf_gain, lpf_qFactor, and TAG.

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◆ convert_float2short()

void convert_float2short	(	float *	float_data,
		int16_t *	int16_data,
		int	len )

static

Definition at line 119 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

{
    float multiplier = (float)(INT16_MAX + 1);
    for (int i = 0 ; i < len ; i++) {
        int16_data[i] = (int16_t)((float)multiplier * (float)float_data[i]);
    }
}

Referenced by audio_read_task().

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◆ convert_short2float()

void convert_short2float	(	int16_t *	int16_data,
		float *	float_data,
		int	len )

static

Definition at line 110 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

{
    float multiplier = 1.0 / (float)(INT16_MAX + 1);
    for (int i = 0 ; i < len ; i++) {
        float_data[i] = (float)int16_data[i] * multiplier;
    }
}

Referenced by audio_read_task().

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◆ digitalLimiter()

void digitalLimiter	(	float *	input_signal,
		float *	output_signal,
		int	signal_length,
		float	threshold,
		float	attack_value,
		float	release_value,
		float *	in_envelope )

Definition at line 133 of file external_examples/1fa4e38f/lyrat_board_app/main/audio_amp_main.c.

{
    float envelope = *in_envelope;
    for (int i = 0; i < signal_length; i++) {
        // Calculate envelope
        float abs_input = fabsf(input_signal[i]);
        if (abs_input > envelope) {
            envelope = envelope * (1 - attack_value) + attack_value * abs_input;
        } else {
            envelope = envelope * (1 - release_value) + release_value * abs_input;
        }
 
        // Apply compression
        if (envelope > threshold) {
            output_signal[i] = input_signal[i] * (threshold / envelope);
        } else {
            output_signal[i] = input_signal[i];
        }
    }
    *in_envelope = envelope;
}