Re: [Ekiga-list] configuration

[yannick <sevmek free fr>]

Hi,

Le jeudi 28 février 2008 à 10:54 +0000, John Hawley a écrit :
> Thanks for your suggestions, I believe you have grasped the essence of 
> the problem but perhaps there are one or two other points I should clarify;
> 
> 1. It is my understanding that virtually all fixed broadband lines in 
> the UK are via one of two routes;
> 
> either
> 
> Attached to the cable TV network where much faster download rates are 
> possible ( and I know that upload rates are at least 384k ) This option 
> is not available locally as there is no local cable network.
> 
> or
> 
> Via standard copper telephone lines where the maximum achievable 
> download rate is ~8meg. Unfortunately, effectively all of the copper 
> network is owned by BT which once used to be the state monopoly 
> telephone provider (been privatised ~20years) thus any ISP provider can 
> only offer a service which includes and uses a BT telephone line ( and 
> they think M$ is bad!) I have not gone into the subject exhaustively, 
> but my friendly local BT network engineer ( well fishing buddy actually) 
> tell me there's no real way of getting BT to modify the upload rates and 
> in any event, they would prefer to sell you their own garbage videophone 
> package and so have no commercial interest in upping speeds.
> 
> If I am wrong in the above assessment, please let me know as I would 
> drop the monolithic BT for a better service at the first possible 
> opportunity!
> 

The size of the pipe isn't an issue here if you use a good video codec.
The purpose of the video codec is to compress the signal while keeping a
nice image. 250K should be enough if you can use the best video codec to
my knowledge: H.264 (as far as I tested it)
(especially if you don't use sound).
The incoming Ekiga 3.0 will use this codec.

The second important thing is how much video frame the software you use
can produce per second (this is also directly related to your webcam
capabilities). Today, you'll find webcams able to do 640x480 pixels at
25 frames per second. (which is similar to TV and cinema)
Ekiga 3.0 will support 25 frames per seconds.
Matthias has done some tests here about this (well, some times ago...):
http://wiki.ekiga.org/index.php/Video_Calls#Supported_Video_Settings
H.264 will use half bandwidth than the H.263 you'll find in this table.

The H.264 video codec is the one "ichat" use on Mac computers (from
apple).

It doesn't matter if your webcam can produce higher resolutions as the
driver must be able to reduce the resolution to the one fitting the best
your needs. (e.g. 320x240 pixels)

> 
> 2. The hardware currently in use is
> 
> end 1. AMD 2.4gHz semperon + 512 meg ram + Philips webcam + win 2K pro 
> sp4 (but can quickly add linux if deemed advantageous) However, whatever 
> I do at this end, it must be suitable for use by a partially sighted 87 
> year old with no knowledge of computers other than switch on and switch off.
> 
> end 2. Packard bell dual core Pentium 1.6 gHz laptop with 1 gig of ram 
> and a built in Bison? webcam - this webcam is not recognised by Linux. 
> OS = xp sp2 or Ubuntu Gutsy Gibbon.
> 
> 

A good video codec like H.264 use most CPU than the other video codecs.
Thus it is important:
1- this codec is optimized. Ekiga use the well know ffmpeg library for
the H.264 codec. This library is know to give good results in both speed
and quality.
2- the video display on your screen is optimized by your graphic card.
Ekiga 3.0 will use the graphic card to speed up the display, thus
freeing your CPU for the video encoding/decoding part of the process.

> Thus for the moment anyway, webcam/video driver issues seem to dictate a 
> windows environment although if making this system work correctly means 
> the purchase of a couple of new webcams - so be it! My reluctance to buy 
> "better" webcams is that the newer they are, the higher the resolution 
> seems to be and the more bandwidth that is then required!
> 
> 
> 
> As for the mechanics of packet traffic through the internet, I must 
> confess I've never really looked into it. If there is a way of forcing 
> higher priority and share of available bandwidth, please point me to a 
> site where I can read up on it.
> 

The SIP protocol Ekiga use is UDP based and peer to peer which is the
fastest you can get from the internet.

As SIP is a standard for internet, we could expect internet to tag
packets from SIP as high priority for low latency. I doubt this is the
case today...

Regards,
Yannick
> 
> 
> As a final point, Ive just received an email from Damien on the subject 
> of Ekiga 3.00 and I need to read this thoroughly and check out the 
> repositories before doing anything drastic. But thanks once again for 
> the suggestions I may well come back to you for more information
> 
> 
> Regards John H
> 
> 
> 
> 
> _______________________________________________
> ekiga-list mailing list
> ekiga-list gnome org
> http://mail.gnome.org/mailman/listinfo/ekiga-list
> 
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