Recover video frame from decoded data

[Ahmad Alhilal]

I'm working of reliable UDP-based video transmission. I found no way to recover the original video frame, As show in video Receiver last line.

Do you have an example, idea or instructions that may help?

Video Sender 

# iterate on video frames & initiate a generation for each
cap = cv2.VideoCapture('game.mp4')
while cap.isOpened():
    check, frame = cap.read()

    # compute symbols based on frame and symbol_size
    data_in = bytearray(frame)
    settings['symbol_size'] = 1400
    settings['symbols'] = int(math.ceil(len(data_in)/settings['symbol_size']))

    # setup kodo encoder & send settings to server side
    encoder = kodo.RLNCEncoder(
        field=kodo.field.binary8,
        symbols=settings['symbols'],
        symbol_size=settings['symbol_size'])
    encoder.set_symbols_storage(data_in)

   # Encode, produce and send packets

Video Receiver

#receive the encoded packets from client side

# Setup kodo decoder
decoder = kodo.RLNCDecoder(
    field=kodo.field.binary8,
    symbols=settings['symbols'],
    symbol_size=settings['symbol_size'])

data_out = bytearray(decoder.block_size())
decoder.set_symbols_storage(data_out)

# Decode coded packets
..............

#Recover the original video frame
original_frame = np.frombuffer(data_out, dtype=np.dtype(int))

Thank you,

Ahmad.

[Morten V. Pedersen]

Hi Ahmad,
Just to understand correctly. The decoder reports that it is complete - but the decoded data is not in data_out? Did I understand that correctly?

- M

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[Ahmad Alhilal]

Hi Morten,

I found out the problem and the possible solution. 

settings['symbols'] = len(data_in)/settings['symbol_size']

The result number of symbols gives fraction like 184.4. When I round it up (using math.ceil), the encoder and decoder will code extra bytes compared to data_in 

data_in=bytearray(frame)

At the end data_out has extra bytes due to the last packet (i.e. last symbol).

Thank you,

Ahmad.

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[Ahmad Alhilal]

Dear Morten,

Referring to the same problem, the decoder reports that it is complete - but the decoded data is not in data_out.
The application is reliable UDP-based frame sharing (or video transmission). When I use traffic control tool (tc) to apply packet loss, I get distorted frames. Moreover, most of received data are corrupted which hinders runing VPx decoding.

Any idea how to solve this issue?

On Tuesday, April 14, 2020 at 4:51:38 AM UTC+8, Morten V. Pedersen wrote:

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