Feat/tts streaming (#994)

* wip

* add TtsStreamingBuffer class to abstract handling of streaming tokens

* wip

* add throttling support

* support background ttsStream (#995)

* wip

* add TtsStreamingBuffer class to abstract handling of streaming tokens

* wip

* support background ttsStream

* wip

---------

Co-authored-by: Dave Horton <daveh@beachdognet.com>

* wip

* dont send if we have nothing to send

* initial testing with cartesia

* wip

---------

Co-authored-by: Hoan Luu Huu <110280845+xquanluu@users.noreply.github.com>

lib/utils/background-task-manager.js

@@ -46,6 +46,9 @@ class BackgroundTaskManager extends Emitter {
       case 'transcribe':
         task = await this._initTranscribe(opts);
         break;
+      case 'ttsStream':
+        task = await this._initTtsStream(opts);
+        break;
       default:
         break;
     }
@@ -173,6 +176,25 @@ class BackgroundTaskManager extends Emitter {
     return task;
   }
 
+  // Initiate Tts Stream
+  async _initTtsStream(opts) {
+    let task;
+    try {
+      const t = normalizeJambones(this.logger, [opts]);
+      task = makeTask(this.logger, t[0]);
+      const resources = await this.cs._evaluatePreconditions(task);
+      const {span, ctx} = this.rootSpan.startChildSpan(`background-ttsStream:${task.summary}`);
+      task.span = span;
+      task.ctx = ctx;
+      task.exec(this.cs, resources)
+        .then(this._taskCompleted.bind(this, 'ttsStream', task))
+        .catch(this._taskError.bind(this, 'ttsStream', task));
+    } catch (err) {
+      this.logger.info(err, 'BackgroundTaskManager:_initTtsStream - Error creating ttsStream task');
+    }
+    return task;
+  }
+
   _taskCompleted(type, task) {
     this.logger.debug({type, task}, `BackgroundTaskManager:_taskCompleted: task completed, sticky: ${task.sticky}`);
     task.removeAllListeners();