USB Bluetooth Call Bridge

#include <stddef.h>
#include <stdint.h>
#include "esp_err.h"
#include "esp_log.h"
#include "driver/i2s_std.h"
#include "usb_device_uac.h"

#define AUDIO_SAMPLE_RATE_HZ 16000
#define I2S_BCLK_GPIO        12
#define I2S_WS_GPIO          13
#define I2S_DOUT_GPIO        11
#define I2S_DIN_GPIO         10

static const char *TAG = "hfp_usb_bridge";
static i2s_chan_handle_t tx_chan;
static i2s_chan_handle_t rx_chan;

static esp_err_t output_cb(uint8_t *buf, size_t len, void *ctx)
{
    size_t bytes_written = 0;
    return i2s_channel_write(tx_chan, buf, len, &bytes_written, 20);
}

static esp_err_t input_cb(uint8_t *buf, size_t len, size_t *bytes_read, void *ctx)
{
    return i2s_channel_read(rx_chan, buf, len, bytes_read, 20);
}

void app_main(void)
{
    i2s_chan_config_t channel_cfg = I2S_CHANNEL_DEFAULT_CONFIG(I2S_NUM_0, I2S_ROLE_MASTER);
    ESP_ERROR_CHECK(i2s_new_channel(&channel_cfg, &tx_chan, &rx_chan));

    i2s_std_config_t i2s_cfg = {
        .clk_cfg = I2S_STD_CLK_DEFAULT_CONFIG(AUDIO_SAMPLE_RATE_HZ),
        .slot_cfg = I2S_STD_MSB_SLOT_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO),
        .gpio_cfg = {
            .mclk = I2S_GPIO_UNUSED,
            .bclk = I2S_BCLK_GPIO,
            .ws = I2S_WS_GPIO,
            .dout = I2S_DOUT_GPIO,
            .din = I2S_DIN_GPIO,
            .invert_flags = { .mclk_inv = false, .bclk_inv = false, .ws_inv = false },
        },
    };
    ESP_ERROR_CHECK(i2s_channel_init_std_mode(tx_chan, &i2s_cfg));
    ESP_ERROR_CHECK(i2s_channel_init_std_mode(rx_chan, &i2s_cfg));
    ESP_ERROR_CHECK(i2s_channel_enable(tx_chan));
    ESP_ERROR_CHECK(i2s_channel_enable(rx_chan));

    const uac_device_config_t uac_cfg = {
        .output_cb = output_cb,
        .input_cb = input_cb,
        .cb_ctx = NULL,
    };
    ESP_ERROR_CHECK(uac_device_init(&uac_cfg));
    ESP_LOGI(TAG, "USB Audio to BM83 I2S bridge started at %d Hz", AUDIO_SAMPLE_RATE_HZ);
}