Bandwidth in A/V connections?

[Paul E]

How can one determine a reasonable figure that would define the likely
bandwidth used in a 2-way A/V conference in MSN 6.

I am wondering if using it "a lot" (1 hour each day?) will put me over my
ISPs limits for monthly bandwidth.

Thanks,

Paul

 

[Paul E]

Jonathan,

Thank you, as always.

So, if both parties are on broadband, they might well end up with the G.711
codec in use at a bit rate of 64 kbps.

I round that up to 3.9 Mb/minute (60 x 64k with 1024 b/kb), or 0.5 MB/minute
(3.9 Mb / 8 b/B). That means a 2 minute conversation in A/V could be 1 MB
of data? Am I close on this, or WAY out?

That would be 30 MB per hour which seems low given that you could sure
transfer a lot of data (as files) in that time.

If anyone reading this can control their laughter long enough to point out
my more significant errors, I would certainly be pleased for any further
feedback

Thanks,

Paul

 

[Jonathan Kay [MVP]]

Hi Paul,

You're welcome =).

Actually, if bother parties are on broadband (and XP), they'll probably end up on the SIREN
codec (which is actually the best of all of them and chosen over all the others).

There's nothing wrong with your math, but keep in mind that G.711 (and SIREN) is just the
audio codec. The video codec is H.263 (using the QCIF [176x144] format only) which can vary
from 6 to 125 KBps. So, this calculation is much difficult to figure out.

Also, if one stops speaking, Messenger will actually stop transmitting, and as such, would
even skew the results more. This calculation is beginning to need fuzzy logic or the chaos
theory =).
____________________________________________
Jonathan Kay
Windows MVP, Messenger
Associate Expert
http://www.microsoft.com/windowsxp/expertzone/
Messenger Resources - http://messenger.jonathankay.com

 

[Jonathan Kay [MVP]]

Hi Paul,

You're in luck then! You're welcome =).
____________________________________________
Jonathan Kay
Windows MVP, Messenger
Associate Expert
http://www.microsoft.com/windowsxp/expertzone/
Messenger Resources - http://messenger.jonathankay.com

Ha, then I am in luck because I have been told my logic IS fuzzy and I am
known for chaos.

Thanks!

Hi Paul,

You're welcome =).

Actually, if bother parties are on broadband (and XP), they'll probably end up on the SIREN
codec (which is actually the best of all of them and chosen over all the others).

There's nothing wrong with your math, but keep in mind that G.711 (and SIREN) is just the
audio codec. The video codec is H.263 (using the QCIF [176x144] format only) which can vary
from 6 to 125 KBps. So, this calculation is much difficult to figure out.

Also, if one stops speaking, Messenger will actually stop transmitting, and as such, would
even skew the results more. This calculation is beginning to need fuzzy logic or the chaos
theory =).
____________________________________________
Jonathan Kay
Windows MVP, Messenger
Associate Expert
http://www.microsoft.com/windowsxp/expertzone/
Messenger Resources - http://messenger.jonathankay.com

Jonathan,

Thank you, as always.

So, if both parties are on broadband, they might well end up with the G.711
codec in use at a bit rate of 64 kbps.

I round that up to 3.9 Mb/minute (60 x 64k with 1024 b/kb), or 0.5 MB/minute
(3.9 Mb / 8 b/B). That means a 2 minute conversation in A/V could be 1 MB
of data? Am I close on this, or WAY out?

That would be 30 MB per hour which seems low given that you could sure
transfer a lot of data (as files) in that time.

If anyone reading this can control their laughter long enough to point out
my more significant errors, I would certainly be pleased for any further
feedback

Thanks,

Paul



Greetings Paul,

It's hard to say, Messenger actually can use a variety of codecs, and can
even dynamically
change codecs while in a voice/video conversation. See here:
http://msdn.microsoft.com/library/en-us/dnwxp/html/mediainrtcclient.asp

Under 'Audio and Video Codec Availability' you can see the different
bitrates for each.
____________________________________________
Jonathan Kay
Windows MVP, Messenger
Associate Expert
http://www.microsoft.com/windowsxp/expertzone/
Messenger Resources - http://messenger.jonathankay.com

How can one determine a reasonable figure that would define the likely
bandwidth used in a 2-way A/V conference in MSN 6.

I am wondering if using it "a lot" (1 hour each day?) will put me over
my
ISPs limits for monthly bandwidth.

Thanks,

Paul