[vlc-devel] Overhead and JXTA
    Giovane Moreira 
    giovane at gmail.com
       
    Tue Apr  5 21:24:53 CEST 2005
    
    
  
Hello Folks,
I'm studying the vlc performance while I'm streaming multimedia content. 
I streamed a MP3 file (cbr 128kbps) to another machine, 1 hop
distance, and I used snmp to monitoring my ethernet card. I found out
that I need 186,31 kbps (average) to transmit this mp3 file (cbr
128kpbs). In my research I'm trying to measure how much overhead is
generated on many different scenarios.
So I started guessing: -Who's responsable for this overhead? 
In tcp/ip stack, we have:
Application layer: that's where VLC mount the package. JXTA protocol
is used here (that's what ethereal showed me on my linux box)
Transport Layer: VLC use UDP (and there's a little bit overhead here
too - 64 bits per udp package)
Network Layer: IP protocol - a lot of overhead here... IP has many field 
Link Layer: Ethernet  overhead.
So here I am: Is my approach correct? I'm justing summing all fiels of
non-data(I mean, metadata, the data except the mp3 file... such
checksum, port, source fields) of all protocols used in all layers in
transmittion. So if I sum all this then I got my overhead. Is this
correct?
Example: transmit 100 bytes of mp3 file. I should then add the JXLA
overhead (couse of JXLA protocol fields and other protocols). So I
should add UDP overhead (64bits per package) then IP overhead(192bits
per package) and then Ethernet Overhead(26bits per package).
I'm supposing that snmp count all this data.And I got who's generating
the overhead. Is this ok:?
And other question: Why VLC uses JXTA? Why not another api?
Thank you so much,
Giovane
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