[linux-audio-dev] Audio synchronization, MIDI API

[Juan Linietsky]

On Sunday 15 August 2004 06:48, phil at plus24.com wrote:
> The current top Ethernet standard specifies max transmission speed of
> 10GBit/sec - 1394b is 800MBit/sec.
>
> You can also run Ethernet over Firewire.  IIRC the max. number of
> devices on a 1394 chain is 63 making Ethernet more suitable for large
> clusters of interconnected MIDI workstations.
>
> But to an extent arguing over which PHY layer is like a Vi / Emacs
> flamewar.
>
> [plug]
>
> For a working example of a MIDI over Ethernet (and UDP) have a look at
> IEEE P1639 (was called DMIDI):
>
> www.plus24.com/ieeep1639
>
> This acts as a bridge between ALSA and the network so all MIDI apps can
> bounce MIDI data between remote machines without any code changes.
>

I tried this myself, on a 100mbit ethernet switch.. while for single 
instruments it seems okay, and latency is fine, playing full complex midi 
pieces in realtime had a lot of jittering.. I did packet monitoring and it 
all seemed ok (all the network traffic was for midi).. I'm suspecting that
it may be related to the network card or driver doing some sort of buffering..
but I cant really tell.. any experiences about this?

Cheers!

Juan Linietsky




> I'm also working on an embedded Linux for clustering audio workstations,
> Live CD available (USB mouse support broken just for now, PS/2 OK):
>
> www/plus24.com/m-dist
>
> This is also a call for participation in the final development of the
> standard as well as application development.
>
> Regards
>
> Phil
>
>
> On Sunday, August 15, 2004, at 09:36  am, Steve Harris wrote:
>
> But if youre going to do that, why use ethernet? You'd need dedicated
> NICs
> and switches, so you may as well use firewire, which has dedicated
> realtime channels, more bandwidth and doesnt require switching. 400meg
> Firewire cards are down to about 7 or 8 euros in the UK now.
>
> The only disadvantage is that you can't (right now) cheaply run firewire
> over long distances, but taht will change once firewire over CAT5 cards
> come down in price, and this is rarely an issue with clusters anyway.