[ESP32]：百度语音识别-编程知识

[ESP32]：百度语音识别

1.开发环境：

esp-idf 5.1
esp32 s3
microphone:MSM261S4030H0

百度文档：短语音识别标准版API

这里请求我们选择RAW方式

Content-Type: audio/pcm;rate=16000

请求格式如下：

POST http://vop.baidu.com/server_api?dev_pid=1537&cuid=******&token=1.a6b7dbd428f731035f771b8d********.86400.1292922000-2346678-124328

2.ESP32

1.整体流程：

录音
转成wav格式，保存至spiffs
读取保存的wav文件到buffer
调用http client

关于这里为什么要保存到spiffs，主要是考虑到录制的时间太长的，malloc一块大buffer容易失败

2.spiffs创建

我的分区表如下

# Name,   Type, SubType, Offset,  Size, Flags
# Note: if you have increased the bootloader size, make sure to update the offsets to avoid overlap
nvs,      data, nvs,     0x9000,  0x6000,
phy_init, data, phy,     0xf000,  0x1000,
factory,  app,  factory, 0x10000, 1M,
storage,  data, spiffs,  ,        2000K,

关于spiffs可以参考idf的例子，我的如下

#include "app_spiffs.h"static const char *TAG = "SPIFFS";esp_err_t app_spiffs_init(char *mount_path)
{esp_err_t ret;esp_vfs_spiffs_conf_t conf = {.base_path = mount_path,.partition_label = NULL,.max_files = 5,.format_if_mount_failed = true, // 如果挂载失败，将格式化文件系统};ESP_ERROR_CHECK(esp_vfs_spiffs_register(&conf));// 检查spiffsret = esp_spiffs_check(conf.partition_label);if (ret != ESP_OK){ESP_LOGI(TAG, "SPIFFS Check failed:%s", esp_err_to_name(ret));}else{ESP_LOGI(TAG, "SPIFFS Check success");}// 获取spiffs的信息size_t total = 0, used = 0;ret = esp_spiffs_info(conf.partition_label, &total, &used);if (ret != ESP_OK){ESP_LOGI(TAG, "Failed to get spiffs partition info:%s", esp_err_to_name(ret));return ESP_FAIL;}else{ESP_LOGI(TAG, "Partition size: total:%d,used:%d ", total, used);}// 如果used > total，再次检查if (used > total){ESP_LOGW(TAG, "Number of used bytes cannot be larger than total. Performing SPIFFS_check().");ret = esp_spiffs_check(conf.partition_label);if (ret != ESP_OK){ESP_LOGE(TAG, "SPIFFS_check() failed (%s)", esp_err_to_name(ret));return ESP_FAIL;}else{ESP_LOGI(TAG, "SPIFFS_check() successful");}}return ret;
}

3.i2s初始化

i2s的录音主要参考idf的例子：IDF I2S录音

#include "hal_i2s.h"
#include "app_spiffs.h"
#include <sys/unistd.h>
#include <sys/stat.h>
#include "esp_log.h"
#include "esp_heap_caps.h"static const char *TAG = "AUDIO";
i2s_chan_handle_t rx_handle = NULL;
record_info_t record_info = {};esp_err_t hal_i2s_microphone_init(i2s_microphone_config_t config)
{esp_err_t ret_val = ESP_OK;i2s_chan_config_t chan_cfg = I2S_CHANNEL_DEFAULT_CONFIG(config.i2s_num, I2S_ROLE_MASTER);ret_val |= i2s_new_channel(&chan_cfg, NULL, &rx_handle);i2s_std_config_t std_cfg = {.clk_cfg = I2S_STD_CLK_DEFAULT_CONFIG(config.sample_rate),.slot_cfg = I2S_STD_PHILIPS_SLOT_DEFAULT_CONFIG(config.bits_per_sample, I2S_SLOT_MODE_MONO),.gpio_cfg = {.mclk = GPIO_NUM_NC,.bclk = config.bclk_pin,.ws = config.ws_pin,.dout = GPIO_NUM_NC,.din = config.din_pin,.invert_flags = {.mclk_inv = false,.bclk_inv = false,.ws_inv = false,},},};std_cfg.slot_cfg.slot_mask = I2S_STD_SLOT_LEFT;ret_val |= i2s_channel_init_std_mode(rx_handle, &std_cfg);ret_val |= i2s_channel_enable(rx_handle);record_info.i2s_config = config;return ret_val;
}void hal_i2s_record(char *file_path, int record_time)
{ESP_LOGI(TAG, "Start Record");record_info.flash_wr_size = 0;record_info.byte_rate = 1 * record_info.i2s_config.sample_rate * record_info.i2s_config.bits_per_sample / 8; // 声道数×采样频率×每样本的数据位数/8。播放软件利用此值可以估计缓冲区的大小。record_info.bytes_all = record_info.byte_rate * record_time;                                                 // 设定时间下的所有数据大小record_info.sample_size = record_info.i2s_config.bits_per_sample * 1024;                                     // 每一次采样的带下const wav_header_t wav_header = WAV_HEADER_PCM_DEFAULT(record_info.bytes_all, record_info.i2s_config.bits_per_sample, record_info.i2s_config.sample_rate, 1);// 判断文件是否存在struct stat st;if (stat(file_path, &st) == 0){ESP_LOGI(TAG, "%s exit", file_path);unlink(file_path); // 如果存在就删除}// 创建WAV文件FILE *f = fopen(file_path, "a");if (f == NULL){ESP_LOGI(TAG, "Failed to open file");return;}fwrite(&wav_header, sizeof(wav_header), 1, f);while (record_info.flash_wr_size < record_info.bytes_all){char *i2s_raw_buffer = heap_caps_calloc(1, record_info.sample_size, MALLOC_CAP_DMA);if (i2s_raw_buffer == NULL){continue;}// Malloc successif (i2s_channel_read(rx_handle, i2s_raw_buffer, record_info.sample_size, &record_info.read_size, 100) == ESP_OK){fwrite(i2s_raw_buffer, record_info.read_size, 1, f);record_info.flash_wr_size += record_info.read_size;}else{ESP_LOGI(TAG, "Read Failed!\n");}free(i2s_raw_buffer);}ESP_LOGI(TAG, "Recording done!");fclose(f);ESP_LOGI(TAG, "File written on SDCard");
}

#pragma once#include "driver/i2s_common.h"
#include "driver/i2s_std.h"
#include "driver/i2s_tdm.h"
#include "driver/gpio.h"
#include "driver/i2s_pdm.h"
#include "wav_formate.h"typedef struct
{uint16_t sample_rate;uint16_t bits_per_sample;gpio_num_t ws_pin;gpio_num_t bclk_pin;gpio_num_t din_pin;i2s_port_t i2s_num;
} i2s_microphone_config_t;typedef struct
{i2s_microphone_config_t i2s_config; // i2s的配置信息int byte_rate;                      // 1s下的采样数据int bytes_all;                      // 录音时间下的所有数据大小int sample_size;                    // 每一次采样的大小int flash_wr_size;                  // 当前录音的大小size_t read_size;                   // i2s读出的长度
} record_info_t;extern i2s_chan_handle_t rx_handle;esp_err_t hal_i2s_microphone_init(i2s_microphone_config_t config);
void hal_i2s_record(char *file_path, int record_time);

4.http请求

首先我们把保存的wav文件读取出来

wav_file = fopen("/spiffs/record.wav", "r");
if (wav_file == NULL)
{ESP_LOGI(TAG, "Read audio file failed");
}
fseek(wav_file, 0, SEEK_END);
wav_file_size = ftell(wav_file);
fseek(wav_file, 0, SEEK_SET);
ESP_LOGI(TAG, "WAV File size:%zu", wav_file_size);
wav_raw_buffer = heap_caps_malloc(wav_file_size + 1, MALLOC_CAP_DMA);
if (wav_raw_buffer == NULL)
{ESP_LOGI(TAG, "Malloc wav raw buffer fail");return;
}
fread(wav_raw_buffer, 1, wav_file_size, wav_file);
fclose(wav_file);

1.设置esp http client的url

char *access_token = "xxx";
char *url_formate = "http://vop.baidu.com/server_api?dev_pid=1537&cuid=dPKArKm9yCGIOwPoCSjTDzmIIj4cBsEV&token=%s";

这里的access_token需要自己去api控制台获取

2.然后设置header

esp_http_client_set_header(client, "Content-Type", "audio/pcm;rate=16000");
esp_http_client_set_header(client, "Accept", "application/json");

3.填写post_field

esp_http_client_set_post_field(client, wav_raw_buffer, wav_file_size);

4.整体调用

void app_main(void)
{// Init NVSesp_err_t ret = nvs_flash_init();if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND){ESP_ERROR_CHECK(nvs_flash_erase());ret = nvs_flash_init();}ESP_ERROR_CHECK(ret);// Connect WIFIapp_wifi_init("MERCURY_5B00", "tzyjy12345678");// Init spiffsESP_ERROR_CHECK(app_spiffs_init("/spiffs"));// Init i2s microphoneESP_ERROR_CHECK(hal_i2s_microphone_init(i2s_microphone_config));hal_i2s_record("/spiffs/record.wav", 5);wav_file = fopen("/spiffs/record.wav", "r");if (wav_file == NULL){ESP_LOGI(TAG, "Read audio file failed");}fseek(wav_file, 0, SEEK_END);wav_file_size = ftell(wav_file);fseek(wav_file, 0, SEEK_SET);ESP_LOGI(TAG, "WAV File size:%zu", wav_file_size);wav_raw_buffer = heap_caps_malloc(wav_file_size + 1, MALLOC_CAP_DMA);if (wav_raw_buffer == NULL){ESP_LOGI(TAG, "Malloc wav raw buffer fail");return;}fread(wav_raw_buffer, 1, wav_file_size, wav_file);fclose(wav_file);// HTTPesp_http_client_config_t config = {.method = HTTP_METHOD_POST,.event_handler = app_http_baidu_speech_recognition_event_handler,.buffer_size = 4 * 1024,};char *url = heap_caps_malloc(strlen(url_formate) + strlen(access_token) + 1, MALLOC_CAP_DMA);sprintf(url, url_formate, access_token);config.url = url;client = esp_http_client_init(&config);esp_http_client_set_method(client, HTTP_METHOD_POST);esp_http_client_set_header(client, "Content-Type", "audio/pcm;rate=16000");esp_http_client_set_header(client, "Accept", "application/json");esp_http_client_set_post_field(client, wav_raw_buffer, wav_file_size);esp_err_t err = esp_http_client_perform(client);if (err == ESP_OK){ESP_LOGI(TAG, "HTTP GET Status = %d, content_length = %d", esp_http_client_get_status_code(client), (int)esp_http_client_get_content_length(client));}else{ESP_LOGI(TAG, "HTTP GET request failed: %s", esp_err_to_name(err));}esp_http_client_cleanup(client);free(url);
}