Herald v2 (#74)

* Add speech rate setting

* Add volume slider

* New speech manager skeleton

* User API key from resx

* Implement voice list retrieve via new api

* Rewrite to use ObAPI, remove all dependancies

* Use volume setting

* Clean up using statements

* Volume and timing adjustments

* Lookup rate value

* Use numeric rates for tighter spread

* Manage plugin data folder via core interface

* Add check that nullable settings are not null.

* Get file size before it's deleted.

* Improve old settings migration.

* Ignore cache sizes below 1MB

* Re-index orphaned files in cache, purge legacy wav files.

* Call top level error logging for native voice exception.

* Async title and detail requests to remove pause

* Remove NetCoreAudio use of temp files.

* Remove orphan using.

ObservatoryCore/NativeNotification/NativeVoice.cs

@@ -32,7 +32,14 @@ namespace Observatory.NativeNotification
 
         private async void ProcessQueueAsync()
         {
-            await Task.Factory.StartNew(ProcessQueue);
+            try
+            {
+                await Task.Factory.StartNew(ProcessQueue);
+            }
+            catch (System.Exception ex)
+            {
+                ObservatoryCore.LogError(ex, " - Native Voice Notifier");
+            }
         }
 
         private void ProcessQueue()

ObservatoryCore/ObservatoryCore.cs

@@ -22,15 +22,19 @@ namespace Observatory
             }
             catch (Exception ex)
             {
-                var docPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.MyDocuments);
-                var errorMessage = new System.Text.StringBuilder();
-                errorMessage
-                    .AppendLine($"Error encountered in Elite Observatory {version}.")
-                    .AppendLine(FormatExceptionMessage(ex))
-                    .AppendLine();
-                System.IO.File.AppendAllText(docPath + System.IO.Path.DirectorySeparatorChar + "ObservatoryErrorLog.txt", errorMessage.ToString());
+                LogError(ex, version);
             }
+        }
 
+        internal static void LogError(Exception ex, string context)
+        {
+            var docPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.MyDocuments);
+            var errorMessage = new System.Text.StringBuilder();
+            errorMessage
+                .AppendLine($"Error encountered in Elite Observatory {context}.")
+                .AppendLine(FormatExceptionMessage(ex))
+                .AppendLine();
+            System.IO.File.AppendAllText(docPath + System.IO.Path.DirectorySeparatorChar + "ObservatoryErrorLog.txt", errorMessage.ToString());
         }
 
         static string FormatExceptionMessage(Exception ex, bool inner = false)

ObservatoryCore/PluginManagement/PluginCore.cs

@@ -3,6 +3,7 @@ using Observatory.Framework.Files;
 using Observatory.Framework.Interfaces;
 using Observatory.NativeNotification;
 using System;
+using System.IO;
 
 namespace Observatory.PluginManagement
 {
@@ -145,5 +146,21 @@ namespace Observatory.PluginManagement
         }
 
         public event EventHandler<NotificationArgs> Notification;
+
+        public string PluginStorageFolder
+        {
+            get
+            {
+                var context = new System.Diagnostics.StackFrame(1).GetMethod();
+
+                string folderLocation = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)
+                    + $"{Path.DirectorySeparatorChar}ObservatoryCore{Path.DirectorySeparatorChar}{context.DeclaringType.Assembly.GetName().Name}{Path.DirectorySeparatorChar}";
+
+                if (!Directory.Exists(folderLocation))
+                    Directory.CreateDirectory(folderLocation);
+
+                return folderLocation;
+            }
+        }
     }
 }

ObservatoryFramework/Interfaces.cs

@@ -194,5 +194,10 @@ namespace Observatory.Framework.Interfaces
         /// Returns true if the current LogMonitor state represents a batch-read mode.
         /// </summary>
         public bool IsLogMonitorBatchReading { get; }
+
+        /// <summary>
+        /// Retrieves and ensures creation of a location which can be used by the plugin to store persistent data.
+        /// </summary>
+        public string PluginStorageFolder { get; }
     }
 }

ObservatoryFramework/ObservatoryFramework.xml

@@ -138,6 +138,28 @@
             Specifies the desired renderings of the notification.
             </summary>
         </member>
+        <member name="T:Observatory.Framework.LogMonitorStateChangedEventArgs">
+            <summary>
+            Provides information about a LogMonitor state transition.
+            </summary>
+        </member>
+        <member name="F:Observatory.Framework.LogMonitorStateChangedEventArgs.PreviousState">
+            <summary>
+            The previous LogMonitor state.
+            </summary>
+        </member>
+        <member name="F:Observatory.Framework.LogMonitorStateChangedEventArgs.NewState">
+            <summary>
+            The new, current LogMonitor state.
+            </summary>
+        </member>
+        <member name="M:Observatory.Framework.LogMonitorStateChangedEventArgs.IsBatchRead(Observatory.Framework.LogMonitorState)">
+            <summary>
+            Determins if the given state is a batch read of any form.
+            </summary>
+            <param name="state">The state to evaluate</param>
+            <returns>A boolean; True iff the state provided represents a batch-mode read.</returns>
+        </member>
         <member name="T:Observatory.Framework.PluginException">
             <summary>
             Container for exceptions within plugins which cannot be gracefully handled in context,
@@ -760,6 +782,12 @@
             </summary>
             <param name="status">Player status.json content, deserialized into a .NET object.</param>
         </member>
+        <member name="M:Observatory.Framework.Interfaces.IObservatoryWorker.LogMonitorStateChanged(Observatory.Framework.LogMonitorStateChangedEventArgs)">
+            <summary>
+            Called when the LogMonitor changes state. Useful for suppressing output in certain situations
+            such as batch reads (ie. "Read all") or responding to other state transitions.
+            </summary>
+        </member>
         <member name="M:Observatory.Framework.Interfaces.IObservatoryWorker.ReadAllStarted">
             <summary>
             Method called when the user begins "Read All" journal processing, before any journal events are sent.<br/>
@@ -856,6 +884,21 @@
             Shared application HttpClient object. Provided so that plugins can adhere to .NET recommended behaviour of a single HttpClient object per application.
             </summary>
         </member>
+        <member name="P:Observatory.Framework.Interfaces.IObservatoryCore.CurrentLogMonitorState">
+            <summary>
+            Returns the current LogMonitor state.
+            </summary>
+        </member>
+        <member name="P:Observatory.Framework.Interfaces.IObservatoryCore.IsLogMonitorBatchReading">
+            <summary>
+            Returns true if the current LogMonitor state represents a batch-read mode.
+            </summary>
+        </member>
+        <member name="P:Observatory.Framework.Interfaces.IObservatoryCore.PluginStorageFolder">
+            <summary>
+            Retrieves and ensures creation of a location which can be used by the plugin to store persistent data.
+            </summary>
+        </member>
         <member name="T:Observatory.Framework.PluginUI">
             <summary>
             Class permitting plugins to provide their UI, if any, to Observatory Core.

ObservatoryHerald/AzureSpeechManager.cs

@@ -1,230 +0,0 @@
-using System;
-using System.IO;
-using System.Linq;
-using System.Collections.Generic;
-using System.Net.Http;
-using System.Xml;
-using Microsoft.CognitiveServices.Speech;
-using System.Collections.ObjectModel;
-using Observatory.Framework;
-
-namespace Observatory.Herald
-{
-    internal class VoiceSpeechManager
-    {
-        private string azureKey;
-        private DirectoryInfo cacheLocation;
-        private SpeechConfig speechConfig;
-        private SpeechSynthesizer speech;
-
-        internal VoiceSpeechManager(HeraldSettings settings, HttpClient httpClient)
-        {
-            cacheLocation = new(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) 
-                + $"{Path.DirectorySeparatorChar}ObservatoryCore{Path.DirectorySeparatorChar}ObservatoryHerald{Path.DirectorySeparatorChar}");
-
-            if (!Directory.Exists(cacheLocation.FullName))
-            {
-                Directory.CreateDirectory(cacheLocation.FullName);
-            }
-            
-            try
-            {
-                azureKey = GetAzureKey(settings, httpClient);
-            }
-            catch (Exception ex)
-            {
-                throw new PluginException("Herald", "Unable to retrieve Azure API key.", ex);
-            }
-
-            try
-            {
-                speechConfig = SpeechConfig.FromSubscription(azureKey, "eastus");
-            }
-            catch (Exception ex)
-            {
-                throw new PluginException("Herald", "Error retrieving Azure account details.", ex);
-            }
-
-            speech = new(speechConfig, null);
-
-            settings.Voices = PopulateVoiceSettingOptions();
-        }
-
-        private Dictionary<string, object> PopulateVoiceSettingOptions()
-        {
-            ReadOnlyCollection<VoiceInfo> voices;
-
-            try
-            {
-                voices = speech.GetVoicesAsync().Result.Voices;
-            }
-            catch (Exception ex)
-            {
-                throw new PluginException("Herald", "Unable to retrieve voice list from Azure.", ex);
-            }
-            
-            var voiceOptions = new Dictionary<string, object>();
-
-            var englishSpeakingVoices = from v in voices 
-                                        where v.Locale.StartsWith("en-") 
-                                        select v;
-
-            foreach (var voice in englishSpeakingVoices)
-            {
-                string demonym = GetDemonymFromLocale(voice.Locale);
-
-                voiceOptions.Add(
-                    $"{demonym} - {voice.LocalName}",
-                    voice);
-
-                foreach (var style in voice.StyleList)
-                {
-                    if (!string.IsNullOrWhiteSpace(style))
-                        voiceOptions.Add(
-                            $"{demonym} - {voice.LocalName} - {style}",
-                            voice);
-                }
-            }
-
-            return voiceOptions;
-        }
-
-        private static string GetDemonymFromLocale(string locale)
-        {
-            string demonym;
-
-            switch (locale)
-            {
-                case "en-AU":
-                    demonym = "Australian";
-                    break;
-                case "en-CA":
-                    demonym = "Canadian";
-                    break;
-                case "en-GB":
-                    demonym = "British";
-                    break;
-                case "en-HK":
-                    demonym = "Hong Konger";
-                    break;
-                case "en-IE":
-                    demonym = "Irish";
-                    break;
-                case "en-IN":
-                    demonym = "Indian";
-                    break;
-                case "en-KE":
-                    demonym = "Kenyan";
-                    break;
-                case "en-NG":
-                    demonym = "Nigerian";
-                    break;
-                case "en-NZ":
-                    demonym = "Kiwi";
-                    break;
-                case "en-PH":
-                    demonym = "Filipino";
-                    break;
-                case "en-SG":
-                    demonym = "Singaporean";
-                    break;
-                case "en-TZ":
-                    demonym = "Tanzanian";
-                    break;
-                case "en-US":
-                    demonym = "American";
-                    break;
-                case "en-ZA":
-                    demonym = "South African";
-                    break;
-                default:
-                    demonym = locale;
-                    break;
-            }
-
-            return demonym;
-        }
-
-        internal string GetAudioFileFromSsml(string ssml, string voice, string style)
-        {
-            ssml = AddVoiceToSsml(ssml, voice, style);
-            string ssmlHash = FNV64(ssml).ToString("X");
-
-            string audioFile = cacheLocation + ssmlHash + ".wav";
-
-            if (!File.Exists(audioFile))
-            {
-                using var stream = RequestFromAzure(ssml);
-                stream.SaveToWaveFileAsync(audioFile).Wait();
-            }
-
-            return audioFile;
-        }
-
-        private static ulong FNV64(string data)
-        {
-            string lower_data = data.ToLower();
-            ulong hash = 0xcbf29ce484222325uL;
-            for (int i = 0; i < lower_data.Length; i++)
-            {
-                byte b = (byte)lower_data[i];
-                hash *= 1099511628211uL;
-                hash ^= b;
-            }
-            return hash;
-        }
-
-        private AudioDataStream RequestFromAzure(string ssml)
-        {
-            try
-            {
-                var result = speech.SpeakSsmlAsync(ssml).Result;
-                return AudioDataStream.FromResult(result);
-            }
-            catch (Exception ex)
-            {
-                throw new PluginException("Herald", "Unable to retrieve audio from Azure.", ex);
-            }
-        }
-
-        private static string AddVoiceToSsml(string ssml, string voiceName, string styleName)
-        {
-            XmlDocument ssmlDoc = new();
-            ssmlDoc.LoadXml(ssml);
-
-            var ssmlNamespace = ssmlDoc.DocumentElement.NamespaceURI;
-            XmlNamespaceManager ssmlNs = new(ssmlDoc.NameTable);
-            ssmlNs.AddNamespace("ssml", ssmlNamespace);
-            ssmlNs.AddNamespace("mstts", "http://www.w3.org/2001/mstts");
-
-            var voiceNode = ssmlDoc.SelectSingleNode("/ssml:speak/ssml:voice", ssmlNs);
-
-            voiceNode.Attributes.GetNamedItem("name").Value = voiceName;
-
-            if (!string.IsNullOrWhiteSpace(styleName))
-            {
-                var expressAsNode = ssmlDoc.CreateElement("express-as", "http://www.w3.org/2001/mstts");
-                expressAsNode.SetAttribute("style", styleName);
-                expressAsNode.InnerXml = voiceNode.InnerXml;
-                voiceNode.InnerXml = expressAsNode.OuterXml;
-            }
-            return ssmlDoc.OuterXml;
-        }
-
-        private static string GetAzureKey(HeraldSettings settings, HttpClient httpClient)
-        {
-            string azureKey;
-
-            if (string.IsNullOrWhiteSpace(settings.AzureAPIKeyOverride))
-            {
-                azureKey = httpClient.GetStringAsync("https://xjph.net/Observatory/ObservatoryHeraldAzureKey").Result;
-            }
-            else
-            {
-                azureKey = settings.AzureAPIKeyOverride;
-            }
-
-            return azureKey;
-        }
-    }
-}

ObservatoryHerald/HeraldNotifier.cs

@@ -1,7 +1,6 @@
-using Microsoft.CognitiveServices.Speech;
-using Observatory.Framework;
+using Observatory.Framework;
 using Observatory.Framework.Interfaces;
-using System;
+using System.Text.Json;
 
 namespace Observatory.Herald
 {
@@ -9,11 +8,19 @@ namespace Observatory.Herald
     {
         public HeraldNotifier()
         {
-            heraldSettings = new()
+            heraldSettings = DefaultSettings;
+        }
+
+        private static HeraldSettings DefaultSettings
+        {
+            get => new HeraldSettings()
             {
                 SelectedVoice = "American - Christopher",
-                AzureAPIKeyOverride = string.Empty,
-                Enabled = false
+                SelectedRate = "Default",
+                Volume = 75,
+                Enabled = false,
+                ApiEndpoint = "https://api.observatory.xjph.net/AzureVoice",
+                CacheSize = 100
             };
         }
 
@@ -25,12 +32,29 @@ namespace Observatory.Herald
 
         public PluginUI PluginUI => new (PluginUI.UIType.None, null);
 
-        public object Settings { get => heraldSettings; set => heraldSettings = (HeraldSettings)value; }
-
+        public object Settings
+        {
+            get => heraldSettings;
+            set
+            {
+                // Need to perform migration here, older
+                // version settings object not fully compatible.
+                var savedSettings = (HeraldSettings)value;
+                if (string.IsNullOrWhiteSpace(savedSettings.SelectedRate))
+                {
+                    heraldSettings.SelectedVoice = savedSettings.SelectedVoice;
+                    heraldSettings.Enabled = savedSettings.Enabled;
+                }
+                else
+                {
+                    heraldSettings = savedSettings;
+                }
+            }
+        }
         public void Load(IObservatoryCore observatoryCore)
         {
-            var azureManager = new VoiceSpeechManager(heraldSettings, observatoryCore.HttpClient);
-            heraldSpeech = new HeraldQueue(azureManager);
+            var speechManager = new SpeechRequestManager(heraldSettings, observatoryCore.HttpClient, observatoryCore.PluginStorageFolder);
+            heraldSpeech = new HeraldQueue(speechManager);
             heraldSettings.Test = TestVoice;
         }
 
@@ -43,7 +67,9 @@ namespace Observatory.Herald
                     Detail = $"This is {heraldSettings.SelectedVoice.Split(" - ")[1]}." 
                 }, 
                 GetAzureNameFromSetting(heraldSettings.SelectedVoice),
-                GetAzureStyleNameFromSetting(heraldSettings.SelectedVoice));
+                GetAzureStyleNameFromSetting(heraldSettings.SelectedVoice),
+                heraldSettings.Rate[heraldSettings.SelectedRate].ToString(),
+                heraldSettings.Volume);
         }
 
         public void OnNotificationEvent(NotificationArgs notificationEventArgs)
@@ -52,13 +78,15 @@ namespace Observatory.Herald
                 heraldSpeech.Enqueue(
                     notificationEventArgs, 
                     GetAzureNameFromSetting(heraldSettings.SelectedVoice),
-                    GetAzureStyleNameFromSetting(heraldSettings.SelectedVoice));
+                    GetAzureStyleNameFromSetting(heraldSettings.SelectedVoice),
+                    heraldSettings.Rate[heraldSettings.SelectedRate].ToString(), 
+                    heraldSettings.Volume);
         }
 
         private string GetAzureNameFromSetting(string settingName)
         {
-            var voiceInfo = (VoiceInfo)heraldSettings.Voices[settingName];
-            return voiceInfo.Name;
+            var voiceInfo = (JsonElement)heraldSettings.Voices[settingName];
+            return voiceInfo.GetProperty("ShortName").GetString();
         }
 
         private string GetAzureStyleNameFromSetting(string settingName)

ObservatoryHerald/HeraldQueue.cs

@@ -13,22 +13,32 @@ namespace Observatory.Herald
         private bool processing;
         private string voice;
         private string style;
-        private VoiceSpeechManager azureCacheManager;
+        private string rate;
+        private byte volume;
+        private SpeechRequestManager speechManager;
         private Player audioPlayer;
         
-        public HeraldQueue(VoiceSpeechManager azureCacheManager)
+        public HeraldQueue(SpeechRequestManager speechManager)
         {
-            this.azureCacheManager = azureCacheManager;
+            this.speechManager = speechManager;
             processing = false;
             notifications = new();
             audioPlayer = new();
         }
 
 
-        internal void Enqueue(NotificationArgs notification, string selectedVoice, string selectedStyle = "")
+        internal void Enqueue(NotificationArgs notification, string selectedVoice, string selectedStyle = "", string selectedRate = "", int volume = 75)
         {
             voice = selectedVoice;
             style = selectedStyle;
+            rate = selectedRate;
+            // Ignore invalid values; assume default.
+            volume = volume >= 0 && volume <= 100 ? volume : 75;
+
+            // Volume is perceived logarithmically, convert to exponential curve
+            // to make perceived volume more in line with value set.
+            this.volume = ((byte)System.Math.Floor(System.Math.Pow(volume / 100.0, 2.0) * 100));
+
             notifications.Enqueue(notification);
 
             if (!processing)
@@ -45,50 +55,60 @@ namespace Observatory.Herald
 
         private void ProcessQueue()
         {
+            
             while (notifications.Any())
             {
+                audioPlayer.SetVolume(volume).Wait();
                 var notification = notifications.Dequeue();
 
+                Task<string>[] audioRequestTasks = new Task<string> [2];
+                
+
                 if (string.IsNullOrWhiteSpace(notification.TitleSsml))
                 {
-                    Speak(notification.Title);
+                    audioRequestTasks[0] = RetrieveAudioToFile(notification.Title);
                 }
                 else
                 {
-                    SpeakSsml(notification.TitleSsml);
+                    audioRequestTasks[0] = RetrieveAudioSsmlToFile(notification.TitleSsml);
                 }
 
                 if (string.IsNullOrWhiteSpace(notification.DetailSsml))
                 {
-                    Speak(notification.Detail);
+                    audioRequestTasks[1] = RetrieveAudioToFile(notification.Detail);
                 }
                 else
                 {
-                    SpeakSsml(notification.DetailSsml);
+                    audioRequestTasks[1] = RetrieveAudioSsmlToFile(notification.DetailSsml);
                 }
+
+                PlayAudioRequestsSequentially(audioRequestTasks);
             }
 
             processing = false;
         }
 
-        private void Speak(string text)
+        private async Task<string> RetrieveAudioToFile(string text)
         {
-            SpeakSsml($"<speak version=\"1.0\" xmlns=\"http://www.w3.org/2001/10/synthesis\" xml:lang=\"en-US\"><voice name=\"\">{text}</voice></speak>");
+            return await RetrieveAudioSsmlToFile($"<speak version=\"1.0\" xmlns=\"http://www.w3.org/2001/10/synthesis\" xml:lang=\"en-US\"><voice name=\"\">{text}</voice></speak>");
         }
 
-        private void SpeakSsml(string ssml)
+        private async Task<string> RetrieveAudioSsmlToFile(string ssml)
         {
-            string file = azureCacheManager.GetAudioFileFromSsml(ssml, voice, style);
+            return await speechManager.GetAudioFileFromSsml(ssml, voice, style, rate);
+        }
 
-            // For some reason .Wait() concludes before audio playback is complete.
-            audioPlayer.Play(file);
-            while (audioPlayer.Playing)
+        private void PlayAudioRequestsSequentially(Task<string>[] requestTasks)
+        {
+            foreach (var request in requestTasks)
             {
-                Thread.Sleep(20);
+                string file = request.Result;
+                audioPlayer.Play(file).Wait();
+
+                while (audioPlayer.Playing)
+                    Thread.Sleep(50);
+
             }
         }
-
-        
-
     }
 }

ObservatoryHerald/HeraldSettings.cs

@@ -1,9 +1,6 @@
 using Observatory.Framework;
 using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 
 namespace Observatory.Herald
 {
@@ -15,15 +12,40 @@ namespace Observatory.Herald
         [SettingDisplayName("Voice")]
         [SettingBackingValue("SelectedVoice")]
         [System.Text.Json.Serialization.JsonIgnore]
-        public Dictionary<string, object> Voices { get; internal set; }
+        public Dictionary<string, object> Voices {get; internal set;}
 
         [SettingIgnore]
         public string SelectedVoice { get; set; }
 
+        [SettingBackingValue("SelectedRate")]
+        public Dictionary<string, object> Rate
+        { get => new Dictionary<string, object> 
+            {
+                {"Slowest", "0.5"},
+                {"Slower", "0.75"},
+                {"Default", "1.0"},
+                {"Faster", "1.25"},
+                {"Fastest", "1.5"}
+            }; 
+        }
+
+        [SettingIgnore]
+        public string SelectedRate { get; set; }
+
+        [SettingDisplayName("Volume")]
+        [SettingNumericUseSlider, SettingNumericBounds(0,100,1)]
+        public int Volume { get; set;}
+
         [System.Text.Json.Serialization.JsonIgnore]
         public Action Test { get; internal set; }
 
         [SettingDisplayName("Enabled")]
         public bool Enabled { get; set; }
+
+        [SettingIgnore]
+        public string ApiEndpoint { get; set; }
+
+        [SettingDisplayName("Cache Size (MB): ")]
+        public int CacheSize { get; set; }
     }
 }

ObservatoryHerald/NetCoreAudio/Interfaces/IPlayer.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Threading.Tasks;
+
+namespace NetCoreAudio.Interfaces
+{
+    public interface IPlayer : IDisposable
+    {
+        event EventHandler PlaybackFinished;
+
+        bool Playing { get; }
+        bool Paused { get; }
+
+        Task Play(string fileName);
+        Task Pause();
+        Task Resume();
+        Task Stop();
+        Task SetVolume(byte percent);
+    }
+}

ObservatoryHerald/NetCoreAudio/Player.cs

@@ -0,0 +1,98 @@
+using NetCoreAudio.Interfaces;
+using NetCoreAudio.Players;
+using System;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+
+namespace NetCoreAudio
+{
+    public class Player : IPlayer
+    {
+        private readonly IPlayer _internalPlayer;
+
+        /// <summary>
+        /// Internally, sets Playing flag to false. Additional handlers can be attached to it to handle any custom logic.
+        /// </summary>
+        public event EventHandler PlaybackFinished;
+
+        /// <summary>
+        /// Indicates that the audio is currently playing.
+        /// </summary>
+        public bool Playing => _internalPlayer.Playing;
+
+        /// <summary>
+        /// Indicates that the audio playback is currently paused.
+        /// </summary>
+        public bool Paused => _internalPlayer.Paused;
+
+        public Player()
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+                _internalPlayer = new WindowsPlayer();
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+                _internalPlayer = new LinuxPlayer();
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+                _internalPlayer = new MacPlayer();
+            else
+                throw new Exception("No implementation exist for the current OS");
+
+            _internalPlayer.PlaybackFinished += OnPlaybackFinished;
+        }
+
+        /// <summary>
+        /// Will stop any current playback and will start playing the specified audio file. The fileName parameter can be an absolute path or a path relative to the directory where the library is located. Sets Playing flag to true. Sets Paused flag to false.
+        /// </summary>
+        /// <param name="fileName"></param>
+        /// <returns></returns>
+        public async Task Play(string fileName)
+        {
+            await _internalPlayer.Play(fileName);
+        }
+
+        /// <summary>
+        /// Pauses any ongong playback. Sets Paused flag to true. Doesn't modify Playing flag.
+        /// </summary>
+        /// <returns></returns>
+        public async Task Pause()
+        {
+            await _internalPlayer.Pause();
+        }
+
+        /// <summary>
+        /// Resumes any paused playback. Sets Paused flag to false. Doesn't modify Playing flag.
+        /// </summary>
+        /// <returns></returns>
+        public async Task Resume()
+        {
+            await _internalPlayer.Resume();
+        }
+
+        /// <summary>
+        /// Stops any current playback and clears the buffer. Sets Playing and Paused flags to false.
+        /// </summary>
+        /// <returns></returns>
+        public async Task Stop()
+        {
+            await _internalPlayer.Stop();
+        }
+
+        private void OnPlaybackFinished(object sender, EventArgs e)
+        {
+            PlaybackFinished?.Invoke(this, e);
+        }
+
+        /// <summary>
+        /// Sets the playing volume as percent
+        /// </summary>
+        /// <returns></returns>
+        public async Task SetVolume(byte percent)
+        {
+            await _internalPlayer.SetVolume(percent);
+        }
+
+        public void Dispose()
+        {
+            _internalPlayer.Dispose();
+        }
+    }
+}

ObservatoryHerald/NetCoreAudio/Players/LinuxPlayer.cs

@@ -0,0 +1,33 @@
+using System;
+using System.IO;
+using System.Threading.Tasks;
+using NetCoreAudio.Interfaces;
+
+namespace NetCoreAudio.Players
+{
+    internal class LinuxPlayer : UnixPlayerBase, IPlayer
+    {
+        protected override string GetBashCommand(string fileName)
+        {
+            if (Path.GetExtension(fileName).ToLower().Equals(".mp3"))
+            {
+                return "mpg123 -q";
+            }
+            else
+            {
+                return "aplay -q";
+            }
+        }
+
+        public override Task SetVolume(byte percent)
+        {
+            if (percent > 100)
+                throw new ArgumentOutOfRangeException(nameof(percent), "Percent can't exceed 100");
+
+            var tempProcess = StartBashProcess($"amixer -M set 'Master' {percent}%");
+            tempProcess.WaitForExit();
+
+            return Task.CompletedTask;
+        }
+    }
+}

ObservatoryHerald/NetCoreAudio/Players/MacPlayer.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Threading.Tasks;
+using NetCoreAudio.Interfaces;
+
+namespace NetCoreAudio.Players
+{
+    internal class MacPlayer : UnixPlayerBase, IPlayer
+    {
+        protected override string GetBashCommand(string fileName)
+        {
+            return "afplay";
+        }
+
+        public override Task SetVolume(byte percent)
+        {
+            if (percent > 100)
+                throw new ArgumentOutOfRangeException(nameof(percent), "Percent can't exceed 100");
+
+            var tempProcess = StartBashProcess($"osascript -e \"set volume output volume {percent}\"");
+            tempProcess.WaitForExit();
+
+            return Task.CompletedTask;
+        }
+    }
+}

ObservatoryHerald/NetCoreAudio/Players/UnixPlayerBase.cs

@@ -0,0 +1,110 @@
+using NetCoreAudio.Interfaces;
+using System;
+using System.Diagnostics;
+using System.Threading.Tasks;
+
+namespace NetCoreAudio.Players
+{
+    internal abstract class UnixPlayerBase : IPlayer
+    {
+        private Process _process = null;
+
+        internal const string PauseProcessCommand = "kill -STOP {0}";
+        internal const string ResumeProcessCommand = "kill -CONT {0}";
+
+        public event EventHandler PlaybackFinished;
+
+        public bool Playing { get; private set; }
+
+        public bool Paused { get; private set; }
+
+        protected abstract string GetBashCommand(string fileName);
+
+        public async Task Play(string fileName)
+        {
+            await Stop();
+            var BashToolName = GetBashCommand(fileName);
+            _process = StartBashProcess($"{BashToolName} '{fileName}'");
+            _process.EnableRaisingEvents = true;
+            _process.Exited += HandlePlaybackFinished;
+            _process.ErrorDataReceived += HandlePlaybackFinished;
+            _process.Disposed += HandlePlaybackFinished;
+            Playing = true;
+        }
+
+        public Task Pause()
+        {
+            if (Playing && !Paused && _process != null)
+            {
+                var tempProcess = StartBashProcess(string.Format(PauseProcessCommand, _process.Id));
+                tempProcess.WaitForExit();
+                Paused = true;
+            }
+
+            return Task.CompletedTask;
+        }
+
+        public Task Resume()
+        {
+            if (Playing && Paused && _process != null)
+            {
+                var tempProcess = StartBashProcess(string.Format(ResumeProcessCommand, _process.Id));
+                tempProcess.WaitForExit();
+                Paused = false;
+            }
+
+            return Task.CompletedTask;
+        }
+
+        public Task Stop()
+        {
+            if (_process != null)
+            {
+                _process.Kill();
+                _process.Dispose();
+                _process = null;
+            }
+
+            Playing = false;
+            Paused = false;
+
+            return Task.CompletedTask;
+        }
+
+        protected Process StartBashProcess(string command)
+        {
+            var escapedArgs = command.Replace("\"", "\\\"");
+
+            var process = new Process()
+            {
+                StartInfo = new ProcessStartInfo
+                {
+                    FileName = "/bin/bash",
+                    Arguments = $"-c \"{escapedArgs}\"",
+                    RedirectStandardOutput = true,
+                    RedirectStandardInput = true,
+                    UseShellExecute = false,
+                    CreateNoWindow = true,
+                }
+            };
+            process.Start();
+            return process;
+        }
+
+        internal void HandlePlaybackFinished(object sender, EventArgs e)
+        {
+            if (Playing)
+            {
+                Playing = false;
+                PlaybackFinished?.Invoke(this, e);
+            }
+        }
+
+        public abstract Task SetVolume(byte percent);
+
+        public void Dispose()
+        {
+            Stop().Wait();
+        }
+    }
+}

ObservatoryHerald/NetCoreAudio/Players/WindowsPlayer.cs

@@ -0,0 +1,141 @@
+using NetCoreAudio.Interfaces;
+using System;
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+using System.Timers;
+
+namespace NetCoreAudio.Players
+{
+    internal class WindowsPlayer : IPlayer
+    {
+        [DllImport("winmm.dll")]
+        private static extern int mciSendString(string command, StringBuilder stringReturn, int returnLength, IntPtr hwndCallback);
+
+		[DllImport("winmm.dll")]
+		private static extern int mciGetErrorString(int errorCode, StringBuilder errorText, int errorTextSize);
+
+        [DllImport("winmm.dll")]
+        public static extern int waveOutSetVolume(IntPtr hwo, uint dwVolume);
+
+		private Timer _playbackTimer;
+        private Stopwatch _playStopwatch;
+
+		private string _fileName;
+
+        public event EventHandler PlaybackFinished;
+
+        public bool Playing { get; private set; }
+        public bool Paused { get; private set; }
+
+        public Task Play(string fileName)
+        {
+            _fileName = $"\"{fileName}\"";
+            _playbackTimer = new Timer
+            {
+                AutoReset = false
+            };
+            _playStopwatch = new Stopwatch();
+            
+            ExecuteMciCommand($"Status {_fileName} Length");
+            ExecuteMciCommand($"Play {_fileName}");
+            Paused = false;
+            Playing = true;
+            _playbackTimer.Elapsed += HandlePlaybackFinished;
+            _playbackTimer.Start();
+            _playStopwatch.Start();
+
+            return Task.CompletedTask;
+        }
+
+        public Task Pause()
+        {
+            if (Playing && !Paused)
+            {
+                ExecuteMciCommand($"Pause {_fileName}");
+                Paused = true;
+                _playbackTimer.Stop();
+                _playStopwatch.Stop();
+                _playbackTimer.Interval -= _playStopwatch.ElapsedMilliseconds;
+            }
+
+            return Task.CompletedTask;
+        }
+
+        public Task Resume()
+        {
+            if (Playing && Paused)
+            {
+                ExecuteMciCommand($"Resume {_fileName}");
+                Paused = false;
+                _playbackTimer.Start();
+                _playStopwatch.Reset();
+                _playStopwatch.Start();
+            }
+            return Task.CompletedTask;
+        }
+
+        public Task Stop()
+        {
+            if (Playing)
+            {
+                ExecuteMciCommand($"Stop {_fileName}");
+				Playing = false;
+                Paused = false;
+                _playbackTimer.Stop();
+                _playStopwatch.Stop();
+            }
+            return Task.CompletedTask;
+        }
+
+		private void HandlePlaybackFinished(object sender, ElapsedEventArgs e)
+        {
+            Playing = false;
+            PlaybackFinished?.Invoke(this, e);
+            _playbackTimer?.Dispose();
+            _playbackTimer = null;
+        }
+
+        private Task ExecuteMciCommand(string commandString)
+        {
+            var sb = new StringBuilder();
+
+            var result = mciSendString(commandString, sb, 1024 * 1024, IntPtr.Zero);
+
+            if (result != 0)
+            {
+				var errorSb = new StringBuilder($"Error executing MCI command '{commandString}'. Error code: {result}.");
+				var sb2 = new StringBuilder(128);
+
+				mciGetErrorString(result, sb2, 128);
+				errorSb.Append($" Message: {sb2}");
+
+				throw new Exception(errorSb.ToString());
+            }
+
+            if (commandString.ToLower().StartsWith("status") && int.TryParse(sb.ToString(), out var length))
+                _playbackTimer.Interval = length + 75;
+
+            return Task.CompletedTask;
+        }
+
+        public Task SetVolume(byte percent)
+        {
+            // Calculate the volume that's being set
+            int NewVolume = ushort.MaxValue / 100 * percent;
+            // Set the same volume for both the left and the right channels
+            uint NewVolumeAllChannels = ((uint)NewVolume & 0x0000ffff) | ((uint)NewVolume << 16);
+            // Set the volume
+            waveOutSetVolume(IntPtr.Zero, NewVolumeAllChannels);
+
+            return Task.CompletedTask;
+        }
+
+        public void Dispose()
+        {
+            Stop().Wait();
+            ExecuteMciCommand("Close All");
+        }
+	}
+}

ObservatoryHerald/ObservatoryAPI.Designer.cs

@@ -0,0 +1,72 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace Observatory.Herald {
+    using System;
+    
+    
+    /// <summary>
+    ///   A strongly-typed resource class, for looking up localized strings, etc.
+    /// </summary>
+    // This class was auto-generated by the StronglyTypedResourceBuilder
+    // class via a tool like ResGen or Visual Studio.
+    // To add or remove a member, edit your .ResX file then rerun ResGen
+    // with the /str option, or rebuild your VS project.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "16.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    internal class ObservatoryAPI {
+        
+        private static global::System.Resources.ResourceManager resourceMan;
+        
+        private static global::System.Globalization.CultureInfo resourceCulture;
+        
+        [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
+        internal ObservatoryAPI() {
+        }
+        
+        /// <summary>
+        ///   Returns the cached ResourceManager instance used by this class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Resources.ResourceManager ResourceManager {
+            get {
+                if (object.ReferenceEquals(resourceMan, null)) {
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("Observatory.Herald.ObservatoryAPI", typeof(ObservatoryAPI).Assembly);
+                    resourceMan = temp;
+                }
+                return resourceMan;
+            }
+        }
+        
+        /// <summary>
+        ///   Overrides the current thread's CurrentUICulture property for all
+        ///   resource lookups using this strongly typed resource class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Globalization.CultureInfo Culture {
+            get {
+                return resourceCulture;
+            }
+            set {
+                resourceCulture = value;
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to e698cf7e-0fbc-4e9a-b6a4-2480381afcc1.
+        /// </summary>
+        internal static string ApiKey {
+            get {
+                return ResourceManager.GetString("ApiKey", resourceCulture);
+            }
+        }
+    }
+}

ObservatoryHerald/ObservatoryAPI.resx

@@ -0,0 +1,123 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="ApiKey" xml:space="preserve">
+    <value />
+  </data>
+</root>

ObservatoryHerald/ObservatoryHerald.csproj

@@ -11,30 +11,37 @@
     <AssemblyVersion Condition=" '$(VersionSuffix)' != '' ">$(VersionSuffix)</AssemblyVersion>
     <Version Condition=" '$(VersionSuffix)' == '' ">0.0.1.0</Version>
     <Version Condition=" '$(VersionSuffix)' != '' ">$(VersionSuffix)</Version>
+    <RootNamespace>Observatory.Herald</RootNamespace>
   </PropertyGroup>
-  
-  <ItemGroup>
-    <PackageReference Include="Microsoft.CognitiveServices.Speech" Version="1.18.0" />
-  </ItemGroup>
 
   <ItemGroup>
-    <Reference Include="NetCoreAudio">
-      <HintPath>..\..\NetCoreAudio\NetCoreAudio\bin\Release\netstandard2.0\NetCoreAudio.dll</HintPath>
-    </Reference>
     <Reference Include="ObservatoryFramework">
       <HintPath>..\ObservatoryFramework\bin\Release\net5.0\ObservatoryFramework.dll</HintPath>
     </Reference>
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Update="ObservatoryAPI.Designer.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>ObservatoryAPI.resx</DependentUpon>
+    </Compile>
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Update="ObservatoryAPI.resx">
+      <Generator>ResXFileCodeGenerator</Generator>
+      <LastGenOutput>ObservatoryAPI.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
+  </ItemGroup>
+
+  <ItemGroup>
+    <Folder Include="NetCoreAudio\Players\" />
+  </ItemGroup>
+
   <Target Name="PostBuild" AfterTargets="PostBuildEvent">
     <Exec Condition=" '$(OS)' == 'Windows_NT' " Command="xcopy &quot;$(TargetPath)&quot; &quot;$(ProjectDir)..\ObservatoryCore\$(OutDir)plugins\&quot; /y" />
-    <Exec Condition=" '$(OS)' == 'Windows_NT' " Command="xcopy &quot;$(TargetDir)Microsoft.CognitiveServices.Speech.csharp.dll&quot; &quot;$(ProjectDir)..\ObservatoryCore\$(OutDir)plugins\deps\&quot; /y" />
-    <Exec Condition=" '$(OS)' == 'Windows_NT' " Command="xcopy &quot;$(TargetDir)NetCoreAudio.dll&quot; &quot;$(ProjectDir)..\ObservatoryCore\$(OutDir)plugins\deps\&quot; /y" />
-    <Exec Condition=" '$(OS)' == 'Windows_NT' " Command="xcopy &quot;$(TargetDir)\runtimes\win-x64\native\*.*&quot; &quot;$(ProjectDir)..\ObservatoryCore\$(OutDir)plugins\deps\&quot; /y" />
     <Exec Condition=" '$(OS)' != 'Windows_NT' " Command="[ ! -d &quot;$(ProjectDir)../ObservatoryCore/$(OutDir)plugins/deps&quot; ] &amp;&amp; mkdir -p &quot;$(ProjectDir)../ObservatoryCore/$(OutDir)plugins/deps&quot; || echo Directory already exists" />
-    <Exec Condition=" '$(OS)' != 'Windows_NT' " Command="cp &quot;$(TargetPath)&quot; &quot;$(ProjectDir)../ObservatoryCore/$(OutDir)plugins/&quot; -f" />
-    <Exec Condition=" '$(OS)' != 'Windows_NT' " Command="cp &quot;$(TargetDir)runtimes/linux-x64/lib/netstandard2.0/Microsoft.CognitiveServices.Speech.csharp.dll&quot; &quot;$(ProjectDir)../ObservatoryCore/$(OutDir)plugins/deps/&quot; -f" />
-    <Exec Condition=" '$(OS)' != 'Windows_NT' " Command="cp &quot;$(TargetDir)NetCoreAudio.dll&quot; &quot;$(ProjectDir)../ObservatoryCore/$(OutDir)plugins/deps/&quot; -f" />
   </Target>
   
 </Project>

ObservatoryHerald/SpeechRequestManager.cs

@@ -0,0 +1,295 @@
+using Observatory.Framework;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net.Http;
+using System.Text;
+using System.Text.Json;
+using System.Xml;
+using System.Security.Cryptography;
+using System.Threading.Tasks;
+
+namespace Observatory.Herald
+{
+    class SpeechRequestManager
+    {
+        private HttpClient httpClient;
+        private string ApiKey;
+        private string ApiEndpoint;
+        private DirectoryInfo cacheLocation;
+        private int cacheSize;
+        
+        internal SpeechRequestManager(HeraldSettings settings, HttpClient httpClient, string cacheFolder)
+        {
+            ApiKey = ObservatoryAPI.ApiKey;
+            ApiEndpoint = settings.ApiEndpoint;
+            this.httpClient = httpClient;
+            cacheSize = Math.Max(settings.CacheSize, 1);
+            cacheLocation = new DirectoryInfo(cacheFolder);
+                        
+            if (!Directory.Exists(cacheLocation.FullName))
+            {
+                Directory.CreateDirectory(cacheLocation.FullName);
+            }
+
+            settings.Voices = PopulateVoiceSettingOptions();
+        }
+
+        internal async Task<string> GetAudioFileFromSsml(string ssml, string voice, string style, string rate)
+        {
+
+            ssml = AddVoiceToSsml(ssml, voice, style, rate);
+
+            using var sha = SHA256.Create();
+
+            var ssmlHash = BitConverter.ToString(
+                sha.ComputeHash(Encoding.UTF8.GetBytes(ssml))
+                ).Replace("-", string.Empty);
+
+            var audioFilename = cacheLocation + ssmlHash + ".mp3";
+
+            if (!File.Exists(audioFilename))
+            {
+                using StringContent request = new(ssml)
+                {
+                    Headers = {
+                        { "obs-plugin", "herald" },
+                        { "api-key", ApiKey }
+                    }
+                };
+                
+                using var response = await httpClient.PostAsync(ApiEndpoint + "/Speak", request);
+
+                if (response.IsSuccessStatusCode)
+                {
+                    using FileStream fileStream = new FileStream(audioFilename, FileMode.CreateNew);
+                    response.Content.ReadAsStream().CopyTo(fileStream);
+                    fileStream.Close();
+                }
+                else
+                {
+                    throw new PluginException("Herald", "Unable to retrieve audio data.", new Exception(response.StatusCode.ToString() + ": " + response.ReasonPhrase));
+                }
+
+            }
+
+            UpdateAndPruneCache(new FileInfo(audioFilename));
+                        
+            return audioFilename;
+        }
+
+        private static string AddVoiceToSsml(string ssml, string voiceName, string styleName, string rate)
+        {
+            XmlDocument ssmlDoc = new();
+            ssmlDoc.LoadXml(ssml);
+
+            var ssmlNamespace = ssmlDoc.DocumentElement.NamespaceURI;
+            XmlNamespaceManager ssmlNs = new(ssmlDoc.NameTable);
+            ssmlNs.AddNamespace("ssml", ssmlNamespace);
+            ssmlNs.AddNamespace("mstts", "http://www.w3.org/2001/mstts");
+
+            var voiceNode = ssmlDoc.SelectSingleNode("/ssml:speak/ssml:voice", ssmlNs);
+            voiceNode.Attributes.GetNamedItem("name").Value = voiceName;
+
+            if (!string.IsNullOrWhiteSpace(styleName))
+            {
+                var expressAsNode = ssmlDoc.CreateElement("express-as", "http://www.w3.org/2001/mstts");
+                expressAsNode.SetAttribute("style", styleName);
+                expressAsNode.InnerXml = voiceNode.InnerXml;
+                voiceNode.InnerXml = expressAsNode.OuterXml;
+            }
+
+            if (!string.IsNullOrWhiteSpace(rate))
+            {
+                var prosodyNode = ssmlDoc.CreateElement("prosody", ssmlNamespace);
+                prosodyNode.SetAttribute("rate", rate);
+                prosodyNode.InnerXml = voiceNode.InnerXml;
+                voiceNode.InnerXml = prosodyNode.OuterXml;
+            }
+
+            return ssmlDoc.OuterXml;
+        }
+
+        private Dictionary<string, object> PopulateVoiceSettingOptions()
+        {
+            Dictionary<string, object> voices = new();
+
+            using var request = new HttpRequestMessage(HttpMethod.Get, ApiEndpoint + "/List")
+            {
+                Headers = {
+                    { "obs-plugin", "herald" },
+                    { "api-key", ApiKey }
+                }
+            };            
+
+            var response = httpClient.SendAsync(request).Result;
+
+            if (response.IsSuccessStatusCode)
+            {
+                var voiceJson = JsonDocument.Parse(response.Content.ReadAsStringAsync().Result);
+
+                var englishSpeakingVoices = from v in voiceJson.RootElement.EnumerateArray()
+                                            where v.GetProperty("Locale").GetString().StartsWith("en-")
+                                            select v;
+
+                foreach(var voice in englishSpeakingVoices)
+                {
+                    string demonym = GetDemonymFromLocale(voice.GetProperty("Locale").GetString());
+
+                    voices.Add(
+                        demonym + " - " + voice.GetProperty("LocalName").GetString(),
+                        voice);
+
+                    if (voice.TryGetProperty("StyleList", out var styles))
+                    foreach (var style in styles.EnumerateArray())
+                    {
+                        voices.Add(
+                            demonym + " - " + voice.GetProperty("LocalName").GetString() + " - " + style.GetString(),
+                            voice);
+                    }
+                }
+            }
+            else
+            {
+                throw new PluginException("Herald", "Unable to retrieve available voices.", new Exception(response.StatusCode.ToString() + ": " + response.ReasonPhrase));
+            }
+
+            return voices;
+        }
+
+        private static string GetDemonymFromLocale(string locale)
+        {
+            string demonym;
+
+            switch (locale)
+            {
+                case "en-AU":
+                    demonym = "Australian";
+                    break;
+                case "en-CA":
+                    demonym = "Canadian";
+                    break;
+                case "en-GB":
+                    demonym = "British";
+                    break;
+                case "en-HK":
+                    demonym = "Hong Konger";
+                    break;
+                case "en-IE":
+                    demonym = "Irish";
+                    break;
+                case "en-IN":
+                    demonym = "Indian";
+                    break;
+                case "en-KE":
+                    demonym = "Kenyan";
+                    break;
+                case "en-NG":
+                    demonym = "Nigerian";
+                    break;
+                case "en-NZ":
+                    demonym = "Kiwi";
+                    break;
+                case "en-PH":
+                    demonym = "Filipino";
+                    break;
+                case "en-SG":
+                    demonym = "Singaporean";
+                    break;
+                case "en-TZ":
+                    demonym = "Tanzanian";
+                    break;
+                case "en-US":
+                    demonym = "American";
+                    break;
+                case "en-ZA":
+                    demonym = "South African";
+                    break;
+                default:
+                    demonym = locale;
+                    break;
+            }
+
+            return demonym;
+        }
+
+        private void UpdateAndPruneCache(FileInfo currentFile)
+        {
+            Dictionary<string, CacheData> cacheIndex;
+
+            string cacheIndexFile = cacheLocation + "CacheIndex.json";
+
+            if (File.Exists(cacheIndexFile))
+            {
+                var indexFileContent = File.ReadAllText(cacheIndexFile);
+                try
+                {
+                    cacheIndex = JsonSerializer.Deserialize<Dictionary<string, CacheData>>(indexFileContent);
+                }
+                catch (Exception ex)
+                {
+                    Console.WriteLine(ex.Message);
+                    cacheIndex = new();
+                }
+            }
+            else
+            {
+                cacheIndex = new();
+            }
+
+            // Re-index orphaned files in event of corrupted or lost index.
+            var cacheFiles = cacheLocation.GetFiles("*.mp3");
+            foreach (var file in cacheFiles.Where(file => !cacheIndex.ContainsKey(file.Name)))
+            {
+                cacheIndex.Add(file.Name, new(file.CreationTime, 0));
+            };
+
+            if (cacheIndex.ContainsKey(currentFile.Name))
+            {
+                cacheIndex[currentFile.Name] = new(
+                    cacheIndex[currentFile.Name].Created,
+                    cacheIndex[currentFile.Name].HitCount + 1
+                    );
+            }
+            else
+            {
+                cacheIndex.Add(currentFile.Name, new(DateTime.UtcNow, 1));
+            }
+
+            var currentCacheSize = cacheFiles.Sum(f => f.Length);
+            while (currentCacheSize > cacheSize * 1024 * 1024)
+            {
+
+                var staleFile = (from file in cacheIndex
+                                orderby file.Value.HitCount, file.Value.Created
+                                select file.Key).First();
+
+                if (staleFile == currentFile.Name)
+                    break;
+
+                currentCacheSize -= new FileInfo(cacheLocation + staleFile).Length;
+                File.Delete(cacheLocation + staleFile);
+                cacheIndex.Remove(staleFile);
+            }
+
+            File.WriteAllText(cacheIndexFile, JsonSerializer.Serialize(cacheIndex));
+
+            // Purge cache from earlier versions, if still present.
+            var legacyCache = cacheLocation.GetFiles("*.wav");
+            Array.ForEach(legacyCache, file => File.Delete(file.FullName));
+            
+        }
+
+        public class CacheData
+        {
+            public CacheData(DateTime Created, int HitCount)
+            {
+                this.Created = Created;
+                this.HitCount = HitCount;
+            }
+            public DateTime Created { get; set; }
+            public int HitCount { get; set; }
+        }
+    }
+}