[vls-devel] Re: Occasional crazy problem with vls

[Andrew de Quincey]

On Monday 19 January 2004 13:45, Andrew de Quincey wrote:
> On Monday 19 January 2004 13:34, Jean-Paul Saman wrote:
> > Andrew de Quincey wrote:
> > > Has anyone else seen something like this:
> > >
> > > VLS is playing a looped MPEG2 program stream file, multicasting it as a
> > > UDP MPEG2 transport stream.
> > >
> > > This works fine.. normally.
> > >
> > > However, sometimes _BUT NOT ALWAYS_, when the load on the server is
> > > high (e.g. copying a large mpeg file onto it), VLS goes crazy. It
> > > starts sending the stream out really fast... say 20x the speed it
> > > should. This continues until it hits the end of the file, at which
> > > point it starts playing normally again.
> > >
> > > Note that the problems doesn't always occur... usually videolan behaves
> > > correctly with high loads, but as I said, occasionally this problem
> > > occurs. I'm guessing this is some timestamping problem caused by the
> > > high load, as the file plays perfectly in videolan at all other times.
> > >
> > > I'm asking this because (for various reasons) I'm not using the most
> > > recent version of videolan, although I'm not that far behind. Has
> > > anyone fixed anything like this recently (before I start looking)?
> >
> > I don't think it is a problem as such of VideoLAN. What happens in this
> > scenario is that the copy of the new mpeg file is messing up the
> > harddisk cache. In fact all VLS request for data from the same disk
> > start starving and this will result in sending out *late* packets like a
> > mad man ;-).

I'm not sure if the IO explanation is quite the reason... see that was just 
how I managed to duplicate it. This occurs at random on video servers which 
we know are not having large files or any load of that sort occurring to 
them. The only load is from streaming video either from disk, or from 
DVB-T/DVB-S cards directly to the network interface.

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