Re: Bandwidth calculation

["Anders Broman" <a.broman () telia com>]

  _____  

Från: wireshark-users-bounces () wireshark org
[mailto:wireshark-users-bounces () wireshark org] För Salvatore Frandina
Skickat: den 12 mars 2010 19:38
Till: wireshark-users () wireshark org
Ämne: Re: [Wireshark-users] Bandwidth calculation

 

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...

I’m not sure what you mean by profile 4:2:0

ITU H.263

X.4 Levels of performance capability

:

3) Level 30 * Support of CIF, QCIF and sub-QCIF resolution decoding, capable
of operation

with a bit rate up to 6·(64 000) = 384 000 bits per second with a picture
decoding rate up to

(30 000)/1001 pictures per second.

4) Level 40 * Support of CIF, QCIF and sub-QCIF resolution decoding, capable
of operation

with a bit rate up to 32·(64 000) = 2 048 000 bits per second with a picture
decoding rate up

to (30 000)/1001 pictures per second.



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?

See my previous answer:

The RTP Analysis is designed with voice in mind, time stamps and marker bit
is used differently in

Voice and video I think. For video the marker bit is set for the last packet
belonging to the same

Picture and the timestamp will be the same for all packets making up one
picture (if memory serves).

 

 

Thank

 

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

 

 

-- 

_______________________________________
Salvatore Frandina
website: http://frandinas.altervista.org
mail: salvatore.frandina () gmail com

_______________________________________

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