[LAD] [LAU] Open Source Audio Interface
fons at linuxaudio.org
Thu Sep 11 21:45:31 UTC 2014
On Thu, Sep 11, 2014 at 10:29:24PM +0100, gordonjcp at gjcp.net wrote:
> On Thu, Sep 11, 2014 at 09:17:26PM +0000, Fons Adriaensen wrote:
> > Re. the format used by njbridge: for IPv4 the IP and UDP
> > headers together take 28 bytes. That is less than 2 percent
> > of 1500, and is a small price for having packets that can be
> > handled by switches and routers. There is really no point in
> > trying to reduce that sort of overhead. The njbridge format
> > itself adds a 20 byte header to sample packets. This data is
> > used to identify the packet, to improve the timing and handle
> > skipped cycles, xruns, lost packets and the like. All together
> > the overhead is less than 3.5%.
> But then you *must* take care of timing, since you have no ideai
> if packets passed through a router will arrive in order, how long
> they'll take to traverse it, or even if they'll arrive unmangled
> at all.
The format used by njbridge takes can handle all of that. The current
receiver (n2j) discards packets that arrive out of order (they will
have been replaced by silence before they arrive) but it would be
possible to re-insert them. But being able to do that implies more
latency - a packet can't arrive out of order without being late as
> If you are going to strip it down, just go with bare Ethernet frames :-)
What I wanted to make clear is that there is really no point
in doing that.
A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)
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