I'm working with PyOpenCV. How to convert cv2 image (numpy) to binary string for writing to MySQL db without a temporary file and `imwrite`?

I googled it but found nothing...

I'm trying `imencode`, but it doesn't work.

```
capture = cv2.VideoCapture(url.path)
capture.set(cv2.cv.CV_CAP_PROP_POS_MSEC, float(url.query))
self.wfile.write(cv2.imencode('png', capture.read()))

```

Error:

```
  File "server.py", line 16, in do_GET
  self.wfile.write(cv2.imencode('png', capture.read()))
  TypeError: img is not a numerical tuple

```

Help somebody!