Add TTS API

Author: perlauy

Runtime/OpenAITtsApi.cs

@@ -0,0 +1,87 @@
+using System.Globalization;
+using System.Text;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+using OpenAI;
+using UnityEngine;
+using UnityEngine.Networking;
+
+namespace OpenAI
+{
+    public class CreateTTSRequest {
+        public string model { get; set; }
+        public string input { get; set; }
+        public string voice { get; set; }
+    }
+    
+    public class OpenAITtsApi : OpenAIApi
+    {
+        private const string BASE_PATH = "https://api.openai.com/v1";
+             
+        private Configuration configuration;
+        private Configuration Configuration
+        {
+            get
+            {
+                if (configuration == null)
+                {
+                    configuration = new Configuration();
+                }
+
+                return configuration;
+            }
+        }
+
+        public OpenAIApiTTS(string apiKey = null, string organization = null)
+        {
+            if (apiKey != null)
+            {
+                configuration = new Configuration(apiKey, organization);
+            }
+        }
+
+        /// Used for serializing and deserializing PascalCase request object fields into snake_case format for JSON. Ignores null fields when creating JSON strings.
+        private readonly JsonSerializerSettings jsonSerializerSettings = new()
+        {
+            NullValueHandling = NullValueHandling.Ignore, 
+            ContractResolver = new DefaultContractResolver()
+            {
+                NamingStrategy = new CustomNamingStrategy()
+            },
+            MissingMemberHandling = MissingMemberHandling.Error,
+            Culture = CultureInfo.InvariantCulture
+        };
+        
+        /// <summary>
+        ///     Create byte array payload from the given request object that contains the parameters.
+        /// </summary>
+        /// <param name="request">The request object that contains the parameters of the payload.</param>
+        /// <typeparam name="T">type of the request object.</typeparam>
+        /// <returns>Byte array payload.</returns>
+        private byte[] CreatePayload<T>(T request)
+        {
+            var json = JsonConvert.SerializeObject(request, jsonSerializerSettings);
+            return Encoding.UTF8.GetBytes(json);
+        }
+ 
+        /// <summary>
+        /// Turn text into spoken audio.
+        /// </summary>
+        /// <param name="request">See <see cref="CreateTTSRequest"/></param>
+        /// <returns>See <see cref="CreateTTSResponse"/></returns>
+        public UnityWebRequest CreateTextToSpeechRequest(CreateTTSRequest request)
+        {
+            var path = $"{BASE_PATH}/audio/speech";
+            var payload = CreatePayload(request);
+            
+            UnityWebRequest req = UnityWebRequestMultimedia.GetAudioClip(path, AudioType.MPEG);
+            req.method = UnityWebRequest.kHttpVerbPOST;
+            req.uploadHandler = new UploadHandlerRaw(payload);
+            req.disposeUploadHandlerOnDispose = true;
+            req.disposeDownloadHandlerOnDispose = true;
+            req.SetHeaders(Configuration, ContentType.ApplicationJson);
+
+            return req;
+        }
+    }
+}