fix(audio): prevent empty session replay

ql-application/threadx/interface/custom_app/ws_talkingq.c

@@ -1365,9 +1365,17 @@ sender_loop:
 				continue;
 			}
 
-			if(!app_get_data_call_net_status()) continue;
-
-			if(shine_init==0){
+			if(!app_get_data_call_net_status()) continue;
+
+			/* One recording can release the semaphore many times while the sender
+			 * drains the ring buffer.  A stale token must never create an empty
+			 * session after the previous encoder has already been closed. */
+			left = rb_get_space_used(ring_sender);
+			if(shine_init == 0 && left <= 0){
+				continue;
+			}
+
+			if(shine_init==0){
 				shine_set_config_mpeg_defaults(&(sh_config.mpeg)); //--init sh_config struct
 				sh_config.wave.channels=PCM_MONO; //PCM_STEREO;//PCM_MONO;
 				sh_config.wave.samplerate=16000;//valid samplerates: 44100,48000,32000,22050,24000,16000,11025,12000,8000
@@ -1417,10 +1425,13 @@ sender_loop:
 					sh_shine = NULL;
 				}
 
-				shine_init = 0;
-				
-				audio_packet_type = 0;
-			}
+				shine_init = 0;
+
+				audio_packet_type = 0;
+				/* Discard semaphore tokens already represented by the PCM that this
+				 * session drained.  Recording has stopped, so no new frames race here. */
+				while(ql_rtos_semaphore_wait(sender_sem, 0) == 0) {}
+			}
 	}
 }