fix tts interface error (#2197)

### What problem does this PR solve?

fix tts interface error

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

---------

Co-authored-by: Zhedong Cen <cenzhedong2@126.com>
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

api/apps/conversation_app.py

@@ -196,12 +196,12 @@ def tts():
     tts_mdl = LLMBundle(tenants[0]["tenant_id"], LLMType.TTS, tts_id)
     def stream_audio():
         try:
-            for chunk in tts_mdl(text):  
+            for chunk in tts_mdl.tts(text):  
                 yield chunk  
         except Exception as e:
-            yield "data:" + json.dumps({"retcode": 500, "retmsg": str(e),
+            yield ("data:" + json.dumps({"retcode": 500, "retmsg": str(e),
                             "data": {"answer": "**ERROR**: "+str(e)}},
-                            ensure_ascii=False).encode('utf-8')
+                            ensure_ascii=False)).encode('utf-8')
 
     resp = Response(stream_audio(), mimetype="audio/mpeg")  
     resp.headers.add_header("Cache-Control", "no-cache")

api/db/services/llm_service.py

@@ -194,7 +194,7 @@ class LLMBundle(object):
         for lm in LLMService.query(llm_name=llm_name):
             self.max_length = lm.max_tokens
             break
-
+    
     def encode(self, texts: list, batch_size=32):
         emd, used_tokens = self.mdl.encode(texts, batch_size)
         if not TenantLLMService.increase_usage(
@@ -235,6 +235,17 @@ class LLMBundle(object):
                 "Can't update token usage for {}/SEQUENCE2TXT".format(self.tenant_id))
         return txt
 
+    def tts(self, text):
+        for chunk in self.mdl.tts(text):
+            if isinstance(chunk,int):
+                if not TenantLLMService.increase_usage(
+                    self.tenant_id, self.llm_type, chunk, self.llm_name):
+                        database_logger.error(
+                            "Can't update token usage for {}/TTS".format(self.tenant_id))
+                return
+            yield chunk     
+
+    
     def chat(self, system, history, gen_conf):
         txt, used_tokens = self.mdl.chat(system, history, gen_conf)
         if not TenantLLMService.increase_usage(