add file streaming support

stream.py

@@ -0,0 +1,33 @@
+import time
+import common
+import wave
+
+
+class FileBuffer(object):
+
+    SAMPLES = 4096
+    BUFSIZE = int(SAMPLES * wave.bytes_per_sample)
+    WAIT = 0.1
+    TIMEOUT = 2.0
+
+    def __init__(self, fd):
+        self.fd = fd
+
+    def __iter__(self):
+        return self
+
+    def next(self):
+        block = bytearray()
+        finish_time = time.time() + self.TIMEOUT
+        while time.time() <= finish_time:
+            left = self.BUFSIZE - len(block)
+            data = self.fd.read(left)
+            if data:
+                block.extend(data)
+            if len(block) == self.BUFSIZE:
+                _, values = common.loads(str(block))
+                return values
+
+            time.sleep(self.WAIT)
+
+        raise IOError('timeout')