我结合了GitHub上esp-idf repo中的一些i2 s-adc和sd卡示例，制作了一个程序，对模拟麦克风进行采样，并将录音作为WAV文件存储在SD卡中。问题是，我录制的音频总是以设置为采样的频率的一半播放。
如下面的代码所示，I2S_SAMPLE_RATE被设置为44100 Hz，但如果我播放，听起来好像是在88200 Hz附近采样的。

-I2 s驱动程序以较高的采样率工作。

我已经试过用i2s_set_clk对频率进行编码，但没有运气。

-录制时深度较低，因此会出现一些失真。

我知道esp 32有一个12位ADC，我将BIT_SAMPLE设置为16，但这是否足以导致我所描述的失真类型？

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <sys/unistd.h>
#include <sys/stat.h>
#include "esp_log.h"
#include "esp_err.h"
#include "esp_system.h"
#include "esp_vfs_fat.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/i2s.h"
#include "driver/gpio.h"
#include "driver/spi_common.h"
#include "sdmmc_cmd.h"
#include "sdkconfig.h"
#include "esp_adc_cal.h"
#include "driver/adc.h"

#define V_REF 1100

#define I2S_COMM_MODE 0 // ADC/DAC Mode
#define I2S_SAMPLE_RATE 44100
#define I2S_SAMPLE_BITS 16
#define I2S_BUF_DEBUG 0        // enable display buffer for debug
#define I2S_READ_LEN 16 * 1024 // I2S read buffer length
#define I2S_FORMAT (I2S_CHANNEL_FMT_RIGHT_LEFT)
#define I2S_CHANNEL_NUM 0              // I2S channel number
#define I2S_ADC_UNIT ADC_UNIT_1        // I2S built-in ADC unit
#define I2S_ADC_CHANNEL ADC1_CHANNEL_0 // I2S built-in ADC channel GPIO36

#define SPI_MOSI_GPIO 23
#define SPI_MISO_GPIO 19
#define SPI_CLK_GPIO 18
#define SPI_CS_GPIO 5

static const char *TAG = "I2S_ADC_REC";

#define BIT_SAMPLE 16

#define SPI_DMA_CHAN SPI_DMA_CH_AUTO
#define NUM_CHANNELS 1 // For mono recording only!
#define SD_MOUNT_POINT "/sdcard"
#define SAMPLE_SIZE (BIT_SAMPLE * 1024)
#define BYTE_RATE (I2S_SAMPLE_RATE * (BIT_SAMPLE / 8)) * NUM_CHANNELS

// When testing SD and SPI modes, keep in mind that once the card has been
// initialized in SPI mode, it can not be reinitialized in SD mode without
// toggling power to the card.
sdmmc_host_t host = SDSPI_HOST_DEFAULT();
sdmmc_card_t *card;

static int16_t i2s_readraw_buff[SAMPLE_SIZE];
size_t bytes_read;
const int WAVE_HEADER_SIZE = 44;

/**
 * @brief Initializes the slot without card detect (CD) and write protect (WP) signals.
 * It formats the card if mount fails and initializes the card. After the card has been
 * initialized, it print the card properties
 */
void mount_sdcard(void)
{
    esp_err_t ret;
    // Options for mounting the filesystem.
    // If format_if_mount_failed is set to true, SD card will be partitioned and
    // formatted in case when mounting fails.
    esp_vfs_fat_sdmmc_mount_config_t mount_config = {
        .format_if_mount_failed = true,
        .max_files = 5,
        .allocation_unit_size = 8 * 1024};
    ESP_LOGI(TAG, "Initializing SD card");

    spi_bus_config_t bus_cfg = {
        .mosi_io_num = SPI_MOSI_GPIO,
        .miso_io_num = SPI_MISO_GPIO,
        .sclk_io_num = SPI_CLK_GPIO,
        .quadwp_io_num = -1,
        .quadhd_io_num = -1,
        .max_transfer_sz = 4000,
    };
    ret = spi_bus_initialize(host.slot, &bus_cfg, SPI_DMA_CHAN);
    if (ret != ESP_OK)
    {
        ESP_LOGE(TAG, "Failed to initialize bus.");
        return;
    }

    // This initializes the slot without card detect (CD) and write protect (WP) signals.
    // Modify slot_config.gpio_cd and slot_config.gpio_wp if your board has these signals.
    sdspi_device_config_t slot_config = SDSPI_DEVICE_CONFIG_DEFAULT();
    slot_config.gpio_cs = SPI_CS_GPIO;
    slot_config.host_id = host.slot;

    ret = esp_vfs_fat_sdspi_mount(SD_MOUNT_POINT, &host, &slot_config, &mount_config, &card);

    if (ret != ESP_OK)
    {
        if (ret == ESP_FAIL)
        {
            ESP_LOGE(TAG, "Failed to mount filesystem.");
        }
        else
        {
            ESP_LOGE(TAG, "Failed to initialize the card (%s). "
                          "Make sure SD card lines have pull-up resistors in place.",
                     esp_err_to_name(ret));
        }
        return;
    }

    sdmmc_card_print_info(stdout, card); // Card has been initialized, print its properties
}

/**
 * @brief Generates the header for the WAV file that is going to be stored in the SD card.
 * See this for reference: http://soundfile.sapp.org/doc/WaveFormat/.
 */
void generate_wav_header(char *wav_header, uint32_t wav_size, uint32_t sample_rate)
{
    uint32_t file_size = wav_size + WAVE_HEADER_SIZE - 8;
    uint32_t byte_rate = BYTE_RATE;

    const char set_wav_header[] = {
        'R', 'I', 'F', 'F',                                                  // ChunkID
        file_size, file_size >> 8, file_size >> 16, file_size >> 24,         // ChunkSize
        'W', 'A', 'V', 'E',                                                  // Format
        'f', 'm', 't', ' ',                                                  // Subchunk1ID
        0x10, 0x00, 0x00, 0x00,                                              // Subchunk1Size (16 for PCM)
        0x01, 0x00,                                                          // AudioFormat (1 for PCM)
        0x01, 0x00,                                                          // NumChannels (1 channel)
        sample_rate, sample_rate >> 8, sample_rate >> 16, sample_rate >> 24, // SampleRate
        byte_rate, byte_rate >> 8, byte_rate >> 16, byte_rate >> 24,         // ByteRate
        0x02, 0x00,                                                          // BlockAlign
        0x10, 0x00,                                                          // BitsPerSample (16 bits)
        'd', 'a', 't', 'a',                                                  // Subchunk2ID
        wav_size, wav_size >> 8, wav_size >> 16, wav_size >> 24,             // Subchunk2Size
    };

    memcpy(wav_header, set_wav_header, sizeof(set_wav_header));
}

/**
 * @brief I2S ADC mode init.
 */
void init_microphone(void)
{
    int i2s_num = I2S_COMM_MODE;
    i2s_config_t i2s_config = {
        .mode = I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN | I2S_MODE_ADC_BUILT_IN,
        .sample_rate = I2S_SAMPLE_RATE,
        .bits_per_sample = I2S_SAMPLE_BITS,
        .communication_format = I2S_COMM_FORMAT_STAND_MSB,
        .channel_format = I2S_FORMAT,
        .intr_alloc_flags = 0,
        .dma_buf_count = 6,
        .dma_buf_len = 256,
        .use_apll = 1,
    };

    // Call driver installation function and adc pad.
    ESP_ERROR_CHECK(i2s_driver_install(i2s_num, &i2s_config, 0, NULL));
    ESP_ERROR_CHECK(i2s_set_adc_mode(I2S_ADC_UNIT, I2S_ADC_CHANNEL));
}

void record_wav(uint32_t rec_time)
{
    // Use POSIX and C standard library functions to work with files.
    int flash_wr_size = 0;
    ESP_LOGI(TAG, "Opening file");

    char wav_header_fmt[WAVE_HEADER_SIZE];

    uint32_t flash_rec_size = BYTE_RATE * rec_time;
    generate_wav_header(wav_header_fmt, flash_rec_size, I2S_SAMPLE_RATE);

    // First check if file exists before creating a new file.
    struct stat st;
    if (stat(SD_MOUNT_POINT "/record.wav", &st) == 0)
    {
        // Delete it if it exists
        unlink(SD_MOUNT_POINT "/record.wav");
    }

    // Create new WAV file
    FILE *f = fopen(SD_MOUNT_POINT "/record.wav", "a");
    if (f == NULL)
    {
        ESP_LOGE(TAG, "Failed to open file for writing");
        return;
    }

    // Write the header to the WAV file
    fwrite(wav_header_fmt, 1, WAVE_HEADER_SIZE, f);

    i2s_adc_enable(I2S_CHANNEL_NUM);
    // Start recording
    while (flash_wr_size < flash_rec_size)
    {
        // TODO: The part below needs to be replaced with analog microphone reading //

        // Read the RAW samples from the microphone
        // Read data from I2S bus, in this case, from ADC. //
        i2s_read(I2S_CHANNEL_NUM, (char *)i2s_readraw_buff, SAMPLE_SIZE, &bytes_read, 100);

        // TODO: The part above needs to be replaced with analog microphone reading //

        // Write the samples to the WAV file
        fwrite(i2s_readraw_buff, 1, bytes_read, f);
        flash_wr_size += bytes_read;
    }

    ESP_LOGI(TAG, "Recording done!");
    fclose(f);
    ESP_LOGI(TAG, "File written on SDCard");

    // All done, unmount partition and disable SPI peripheral
    esp_vfs_fat_sdcard_unmount(SD_MOUNT_POINT, card);
    ESP_LOGI(TAG, "Card unmounted");
    // Deinitialize the bus after all devices are removed
    spi_bus_free(host.slot);
}

void app_main(void)
{
    int rec_time = 5;

    ESP_LOGI(TAG, "Analog microphone recording Example start");
    // Mount the SDCard for recording the audio file
    mount_sdcard();

    // I2S ADC mode microphone init.
    init_microphone();

    ESP_LOGI(TAG, "Starting recording for %d seconds!", rec_time);

    // Start Recording
    record_wav(rec_time);

    // Stop I2S driver and destroy
    ESP_ERROR_CHECK(i2s_driver_uninstall(I2S_COMM_MODE));
}

让我知道你认为问题出在哪里，或者/以及你是否有关于这个主题的学习材料的好建议。