python - Convert str to numpy.ndarray

Question

I'm creating a system to share video with opencv but I've got a problem. I've a server and a client but when I send informations to the server, the must be bytes. I send 2 things:

 ret, frame = cap.read()

ret is a booland frame is the data video, a numpy.ndarray ret is not a problem but frame: I convert it in string and then in bytes:

frame = str(frame).encode()
connexion_avec_serveur.send(frame)

I'd like now to convert again frame in a numpy.ndarray.

Answer 1

Your str(frame).encode() is wrong. If you print it to terminal, then you will find it is not the data of the frame.

An alternative method is to use tobytes() and frombuffer().

## read
ret, frame = cap.read()
sz = frame.shape

## tobytes 
frame_bytes = frame.tobytes()
print(type(frame_bytes))
# <class 'bytes'>

## frombuffer and reshape 
frame_frombytes = np.frombuffer(frame_bytes, dtype=np.uint8).reshape(sz)
print(type(frame_frombytes))
## <class 'numpy.ndarray'>

## test whether they equal or not 
print(np.array_equal(frame, frame_frombytes))