[linux-audio-dev] XAP and Event Outputs

Steve Harris S.W.Harris at ecs.soton.ac.uk
Mon Dec 9 10:12:00 UTC 2002


On Mon, Dec 09, 2002 at 03:00:50PM +0100, David Olofson wrote:
> That's the feedback loop problem. As long as the host runs plugins in 
> the correct order, you'll never see this unless you *actually* have 
> loops in your network.

Like in your example ;)

> The way VST does it however, that wouldn't be needed, since 
> timestamps are related to buffers. 0 == start of this buffer. Might 
> look nice to plugins, but I forsee minor nightmares in multithreaded 
> hosts, hosts that want to split buffers, hosts that support different 
> buffer sizes in parts of the net, hosts that support multiple sample 
> rates in the system, communication over wire,... (Yet another reason 
> why I think the VST event system is a pretty bad design.)

Hmm.. I can see why this is tempting, it avoids the wrapping problem,
among other things. Are you sure its not better that way?

Speaking of which what is the conventioanl wisdom on timestamp sizes, 32
sounds dangerous (all the plugins have to work correctly accross the
boundary, hard). and 64 sounds a bit wastefull, though its 4M years at
192k, so you dont have to worry about wrapping ;)
 
> BTW, feedback loops would be the major reason why a host would want 
> to run parts of the net with smaller buffers. See why I discarded the 
> idea of buffer related timestamps? :-)

Ouch. Changing the buffer size sounds messy and inefficient.

- Steve



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