luc117.c

Metadata

• Author — Amit Dutta
• Last updated — 08 Feb 2026
• License — MIT License (See the LICENSE file for details)

Problem Statement

Problem Statement

Write a program to convert a given text into an audio file using OpenAI Audio API (TTS).

Source Code

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>

/* Pre-requisites:
   1. Install libcurl development package.
   2. Get OpenAI API Key.
*/

#define API_KEY "YOUR_OPENAI_API_KEY_HERE"

size_t write_data(void *ptr, size_t size, size_t nmemb, FILE *stream) {
    size_t written = fwrite(ptr, size, nmemb, stream);
    return written;
}

int main(void) {
    CURL *curl;
    CURLcode res;
    FILE *fp;
    
    // JSON Payload construction
    const char *url = "https://api.openai.com/v1/audio/speech";
    const char *data = "{"
                       "\"model\": \"tts-1\","
                       "\"input\": \"Hello! This is a C program talking to you.\","
                       "\"voice\": \"alloy\""
                       "}";

    struct curl_slist *headers = NULL;
    char auth_header[100];
    sprintf(auth_header, "Authorization: Bearer %s", API_KEY);

    curl_global_init(CURL_GLOBAL_ALL);
    curl = curl_easy_init();

    if(curl) {
        // Set Headers
        headers = curl_slist_append(headers, "Content-Type: application/json");
        headers = curl_slist_append(headers, auth_header);
        
        // Open file to save audio
        fp = fopen("output_audio.mp3", "wb");
        if(!fp) {
            printf("Error opening file for writing.\n");
            return 1;
        }

        // Configure CURL
        curl_easy_setopt(curl, CURLOPT_URL, url);
        curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data);
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);

        // Perform Request
        printf("Sending request to OpenAI TTS API...\n");
        res = curl_easy_perform(curl);

        if(res != CURLE_OK)
            fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
        else
            printf("Audio saved to 'output_audio.mp3' successfully.\n");

        // Cleanup
        fclose(fp);
        curl_slist_free_all(headers);
        curl_easy_cleanup(curl);
    }
    
    curl_global_cleanup();
    return 0;
}