Support VITS VCTK models (#367)

* Support VITS VCTK models

* Release v1.8.1

python-api-examples/offline-tts.py

@@ -58,6 +58,16 @@ def get_args():
         help="Path to save generated wave",
     )
 
+    parser.add_argument(
+        "--sid",
+        type=int,
+        default=0,
+        help="""Speaker ID. Used only for multi-speaker models, e.g.
+        models trained using the VCTK dataset. Not used for single-speaker
+        models, e.g., models trained using the LJ speech dataset.
+        """,
+    )
+
     parser.add_argument(
         "--debug",
         type=bool,
@@ -105,7 +115,7 @@ def main():
         )
     )
     tts = sherpa_onnx.OfflineTts(tts_config)
-    audio = tts.generate(args.text)
+    audio = tts.generate(args.text, sid=args.sid)
     sf.write(
         args.output_filename,
         audio.samples,