Re: Turn around time

Giganews Newsgroups
Subject: Re: Turn around time
Posted by:  Martin James (mjames_falc…@dial.pipex.com)
Date: Tue, 11 Jul 2006

> I have a server that delivers video data to a remote client.  Each frame
is
> about 4-20KB.
>
> When the client is on the same machine, the time it takes to send an
entire
> frame of data (plus overhead associated with my protocol) takes approx 1ms
> (between 0 and 2).
>
> A remote connection on a 100base network takes anywhere from 50 to 200ms
per
> frame.  Is this degree of difference to be expected.

Oh yes, probably even greater variation in transit-time is not unusual,
depending on network traffic, whether the routers got out of the right side
of the bed this morning etc.

>In order to get real time we need less than 40ms.  A 1000base network
>certainly helps (don't have timing information for that) but I'm wondering
>if there is something I can configure to push the data faster.

First, do you *need* that much 'real-time'?  If the video at the client is
always ~600ms behind the server, is it that important?  If it is, perhaps
you should consider CCTV with a dedicated connection, rather than networking
it.

If some latency is acceptable, it is usual to buffer the video frames at the
client, extracting frames from the buffer at refresh-rate and keeping the
buffer 'topped-up' by network streaming.  There are protocols for this
already, (mpeg4?).  What protocol are you using at the moment?

Maybee there are some server optimizations.  where do the video buffers come
from, and from where and how do you write them to the server<>client socket
handler/context?

Rgds,
Martin

Replies

In response to

Turn around time posted by Malcolm Smith on Tue, 11 Jul 2006