Video Quality=Network Speed?

Archived from groups: alt.internet.wireless (More info?)

I apologize if this question has been asked before or doesn't belong here,
but I really need some help, and I've done a Google search to no avail.
Basically, I need to determine - before spending a bunch of money - whether
or not a faster home network will improve the video quality I get from my
Dlink DCS-900W wireless network camera. I realize that it's an entry-level
camera, but I can't even get close to using its higher settings, such as
640x480 on medium to low compression, with decent frame rates. Is this a
consequence of my router, which is a Dlink DI614+, or just the limitations
of the camera itself?
Input greatly appreciated.
Thank you,

jakesnake

Archived from groups: alt.internet.wireless (More info?)

On Sun, 01 Aug 2004 23:58:34 GMT, "jakesnake66" <jake@lycos.com>
wrote:

>Basically, I need to determine - before spending a bunch of money - whether
>or not a faster home network will improve the video quality I get from my
>Dlink DCS-900W wireless network camera. I realize that it's an entry-level
>camera, but I can't even get close to using its higher settings, such as
>640x480 on medium to low compression, with decent frame rates. Is this a
>consequence of my router, which is a Dlink DI614+, or just the limitations
>of the camera itself?

It would be helpful if you would disclose the rest of the hardware
you're using for testing and some clue as to the operating system and
computah hardware. The "limitation" could be anywhere in the system
depending upon your hardware.

Also, please define what you consider to be a "decent frame rate"?
Are you expecting full motion video rate (30fps) or did you have
something else in mind? The camera is internally limited to 1, 5, 7,
15, and 20 fps. In the "auto" setting, it will slow down the frame
rate in accordance with the BER (bit error rate) and thruput.

Let's do the math. A 640x480x24bit JPG is about 40K to 60KBytes. If
you plan to send 20 of those every second, you need to have:
50KBytes * 8 bits/byte * 20 frames/sec = 8Mbits/sec
With 802.11b, the fastest connection rate available is 11Mbits/sec
which will deliver 5-6Mbits/sec. That's not enough to maintain 20 fps
which needs 8Mbits/sec. Maintaining an 11Mbit/sec connection is also
somewhat problematic at it requires a good strong signal, no
interference, and good karma. If your DI614+ is running 10baseT half
duplex, the best you can do is about 6-7Mbits/sec, which will also
limit your performance.

I have a DI-614+ in my palatial office and have found a few issues.
You should turn OFF the "4x mode" and reduce the "TX Rates" from
22Mbits/sec to 11Mbits/sec. Leaving these on the defaults causes some
odd preformance problems.
http://support.dlink.com/techtool/ [...] erform.htm


--
Jeff Liebermann jeffl@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558