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Wireshark-users: Re: [Wireshark-users] Bandwidth calculation

From: Salvatore Frandina <salvatore.frandina@xxxxxxxxx>
Date: Fri, 12 Mar 2010 19:38:04 +0100
Hi,

I'm still trying to calculate the bandwidth. I have a problem with the video bandwidth values. The audio bandwidth is correct. G711a requires 64 Kbps Bit rate and 87.2 Kbps Ethernet bandwidth (27% overhead) as reported here http://www.voip-info.org/wiki/view/Bandwidth+consumption.
For video I use H263p and H264. The picture format is CIF with a fps = 1 and profile 4:2:0 so the total video bandwidth without compression is about 355*288*8*1 + 176*144*8*1*(2) = 1.25 Mbits.


I know that H264 codec can reduce the video bandwidth up to 50-60 kbps and 70-80 kbps Ethernet bandwidth. H263p is wore than H264 about 2 times so requires 140-160 kbps Ethernet bandwidth.

I have analyzed with Wireshark 1.2.6 RTP->stream analysis the RTP flow. I have taken in account the six column IP BW with Matlab and I have extract the PDF function. The mean and max bandwidth values are very high respect how I'm expecting. For H263p 343 kbps and 555 kbps...

In the video CSV files of Wireshark I see a lot of incorrect timestamps while in the audio CSV file there are not of these values.


Where could be the problem?


Thank

NB Wireshark calculates IP bandwidth it should be lower that Ethernet bandwidth


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Salvatore Frandina
website: http://frandinas.altervista.org
mail: salvatore.frandina@xxxxxxxxx

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