minor fixes

video_tool.py

@@ -5,8 +5,7 @@ def convert_video_to_audio(input_file, output_file, start_time, end_time):
     (
         ffmpeg
         .input(input_file, ss=start_time, to=end_time)
-        .audio
-        .output(output_file, format="wav")
+        .output(output_file, format="wav", acodec='pcm_s16le')
         .run(overwrite_output=True)
     )