[Winpcap-users] Slow receiving speed (40Mbps), and packet loss.

[Benoit]

Hello,

I'm actually experimenting speed problem with the winpcap 4.0.1
library. I'm doing a software to control a Camera IP and to receive
frames from this one.
The transmission protocol is done at the MAC layer for the moment and
is the following one:

1. PC_MAC    -> CAM_MAC: Ask for a frame.
2. CAM_MAC -> PC_MAC   : Send a frame header packet (64 bytes).
3. CAM_MAC -> PC_MAC   : Send a frame block packet (~1500 bytes).
   Repeat this operation 150 times until the whole image is
transmitted, no ACK packet is used.
4. CAM_MAC -> PC_MAC    : Send a "frame has been sent " packet (32 bytes)
5. PC_MAC    -> CAM_MAC : Send a ACK packet ("frame has been
received") packet (32 bytes), and go back to step 1.

Doing this transmission protocol the speed is limited at 40Mbps which
is very slow for real time video stream.
I've tried to play with the timeout (pcap_open(...)) and with the size
of the buffer (pcap_setbuff(...)) but the results are quite similar.
To capture the packet I'm using the pcap_next_ex().

Finally If i do the same thing with two cameras: The rate is still
40Mbps but I'm loosing half of the packet. This mean for me that the
bottleneck is my program in C++, but I don't know how to solve it...
Maybe if someone has a good sample code with high speed transmission
(~Gbps) it could be helpful to understand where my application failed.

Thanks for your help

--
Benoit RAT
www.neub.co.nr
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