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| Line 2: |
Line 2: |
| | * [[Voice and video analysis]] | | * [[Voice and video analysis]] |
| | * [[Voice-only with different codecs]] | | * [[Voice-only with different codecs]] |
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| − | = Voice and video analysis =
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| − | Schematic sketch of the situation:
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| − | [[image:Schematic overview asterisks and sip-phones.gif|Schematic overview of the test-setup. The colors in the sketch match the colors in the following Ethereal-screenshots]]
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| − | In the screenshot below, the following events were measured:
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| − | * @4 sec: Video was turned on
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| − | * @14 sec: Video was set to black (connection lost with DVdriver)
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| − | * @20 sec: Video showed moving pictures again.
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| − | [[Image:ethereal_graph_voice_and_one-way-video.png]]
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| − | Legenda:
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| − | * '''Black''': traffic from and to Trixbox #1
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| − | * '''Red''': traffic between the 2 Windows machines running X-lite
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| − | * '''Green''': traffic between laptop #1 and its Asterisk
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| − | * '''Blue''': traffic between the two Asterisk PBX's
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| − | * '''Pink''': traffic between Windows machine #1 and its Asterisk
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| − | The following graph shows the traffic is almost constant.
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| − | Till 35sec the conversation included audio and video. The rest is audio-only.
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| − | [[Image:ethereal_graph_voice_and_one-way-video2.png]]
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| − | This measurement shows there is no traffic between both SIP-phones, only via (both) Asterisk PBX.
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| − | = Differences between voice and video =
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| − | For this test ([http://thales.td-er.nl/EtherealDumps/Traffic%20between%202%20SIP%20phones%20with%201%20PBX%20and%201%20camera.rar captured Ethereal data]), we connected 2 SIP phones to the same Asterisk PBX.
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| − | We measured the bandwitdh used between the following 3 points:
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| − | # SIP-phone #1 with camera
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| − | # SIP-phone #2 without camera
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| − | # Asterisk PBX
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| − | [[image:ethereal_graph_difference_voice and video.png|Ethereal graph showing the differences in traffic between audio and video (resp. g711u and H263-1998 codec). Black: from SIP-phone #1 to PBX. Blue: from SIP-phone #2 to PBX
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| − | Pink: all traffic between SIP-phone #1 and the PBX ]]
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| − | '''Legenda:'''
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| − | * '''Black''' shows audio & video from ''SIP-phone #1'' to the PBX (video starting at the 10<sup>th</sup> second)
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| − | * '''Blue''' shows audio-only from ''SIP-phone #2'' to the PBX
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| − | * '''Pink''' shows all traffic between ''SIP-phone #1'' and the PBX (both directions)
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| − | The debug-screen [[image:X-lite debug-info.png|right|315px|X-lite debug-screen]] of X-lite (Ctrl + F9) told us the SIP-phone assumed a total available bandwith of 256/256 kbps.
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| − | This was filled with 64 kbps for speech (protocol g711u) and 131 kbps for video (protocol H263-1998)
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| − | When looking at the speech traffic:
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| − | * 50 packets/sec (measured with Ethereal)
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| − | * 214 Bytes/packet (measured with Ethereal)
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| − | * +/- 10,7 kByte/s
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| − | * 160 bytes audio-data per packet (64 kbps = 8000 Bytes/sec, 50 packets/sec)
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| − | * UDP-packet-header: 28 Bytes.
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| − | Measured IAX-overhead: (the g711u codec uses a CBR of 64kbps) 214 - 28 - 160 = 26 Bytes/packet.
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| − | Thus 1300 Bytes/sec IAX overhead. (10k4 bps)
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