update readme

README.md

@@ -20,13 +20,16 @@
 
 
 ```Python
-import towhee
+from towhee.dc2 import pipe, ops, DataCollection
 
-towhee.glob('./music.mp3').audio_decode.ffmpeg().flatten().show(limit=1)
+p = (
+    pipe.input('audio_file')
+    .flat_map('audio_file', 'frame', ops.audio_decode.ffmpeg())
+    .output('frame')
+)
 
+DataCollection(p('./music.mp3')).show(limit=1)
 
-# batch decode
-# towhee.glob('./music.mp3').audio_decode.ffmpeg(500).flatten().show(limit=1)
 
 ```
 
@@ -43,10 +46,6 @@ Create the operator via the following factory method:
 
 ***audio_decode.ffmpeg()***
 
-batch decode, batch_size = 100:
-
-***audio_decode.ffmpeg(100)***
-
 
 
 <br />