Add ASR demo usage to README.md for DS2.

README.md

@@ -143,3 +143,19 @@ python tune.py --help
 ```
 
 Then reset parameters with the tuning result before inference or evaluating.
+
+### Playing with the ASR Demo
+
+A real-time ASR demo (`demo_server.py` and `demo_client.py`) are prepared for users to try out the ASR model with their own voice. After a model and language model is prepared, we can first start the demo server:
+
+```
+CUDA_VISIBLE_DEVICES=0 python demo_server.py
+```
+And then in another console, start the client:
+
+```
+python demo_client.py
+```
+On the client console, press and hold "white-space" key and start talking, then release the "white-space" key when you finish your speech. The decoding results (infered transcription) will be displayed.
+
+If you would like to start server and client in two machines. Please use `--host_ip` and `--host_port` to indicate the actual IP address and port, for both `demo_server.py` and `demo_client.py`.

demo_client.py

+"""Client-end for the ASR demo."""
 from pynput import keyboard
 import struct
 import socket
 import sys
+import argparse
 import pyaudio
 
-HOST, PORT = "10.104.18.14", 8086
+parser = argparse.ArgumentParser(description=__doc__)
+parser.add_argument(
+    "--host_ip",
+    default="localhost",
+    type=str,
+    help="Server IP address. (default: %(default)s)")
+parser.add_argument(
+    "--host_port",
+    default=8086,
+    type=int,
+    help="Server Port. (default: %(default)s)")
+args = parser.parse_args()
 
 is_recording = False
 enable_trigger_record = True
@@ -42,7 +55,7 @@ def callback(in_data, frame_count, time_info, status):
     elif len(data_list) > 0:
         # Connect to server and send data
         sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        sock.connect((HOST, PORT))
+        sock.connect((args.host_ip, args.host_port))
         sent = ''.join(data_list)
         sock.sendall(struct.pack('>i', len(sent)) + sent)
         print('Speech[length=%d] Sent.' % len(sent))

demo_server.py

+"""Server-end for the ASR demo."""
 import os
 import time
 import random
@@ -17,7 +18,7 @@ from data_utils.utils import read_manifest
 parser = argparse.ArgumentParser(description=__doc__)
 parser.add_argument(
     "--host_ip",
-    default="10.104.18.14",
+    default="localhost",
     type=str,
     help="Server IP address. (default: %(default)s)")
 parser.add_argument(