On Thu, Dec 5, 2013 at 1:28 PM, Ralf Mardorf <[email protected]>wrote:
> Hi :) > > I try to correct the fallacy about latency and to explain it in a > non-exact, non-technically way. > > On Thu, 2013-12-05 at 17:41 +0000, Alex Armani wrote: > > zero-latency kernel > > Even the RT patch with full RT enabled is even not hard real-time > capable, let alone that zero-latency is possible in reality ;). > > There even is latency before the light from your display touches your > eyes and before your perception is able to form a view of what is > displayed. There is no reality with zero-latency. > > Now, important for audio engineering is to understand the differences > between different kinds of preemption and preemption rt. > > Hard real-time e.g. is possible with stand alone gear and oldish > computers, such as the C64, because for such gear and old computers > there's direct access to the hardware, without any layers. For a PC this > is impossible, even not with a kernel-rt. The lowlatency kernel is > relatively far away from a kernel-rt. You will notice that humans are > able to handle latency, since everything in our live comes with latency, > for example analog music instruments have got latency. The issue caused > by PCs is jitter and the low latency kernel does still produce much MIDI > jitter. You can get rid of more, but nor all jitter, if you use full > real-time capabilities enabled, by a patched kernel. Clean audio > production sometimes can be done with a vanilla kernel, since audio > jitter belongs much to the kind of audio card and a vanilla kernel on a > fast PC sometimes does provide more than is enough to get less jitter, > sure you can lower the latency, the harder the kernel does enforce > preemption rt. > > The more layers or regarding to the kind of protocol a layer does talk > to other layers, the higher the latency and the more jitter. I guess the > preemption rt processes within the kernel does optimize priorities, but > can't do much about issues caused by layers. > > At least there definitively is no zero-latency possible, even if PC and > all the layers once should be more precise than old computers were. > > Regards, > Ralf > i read that too, and took note, and assumed "zero-latency" was just a quickly mis-typed reference to the "low-latency" kernel.. though, it is nice to have factual clarification in case someone was wanting copper wire like latency (which is not zero either) and started searching for "ubuntu zero latency kernel"... > > > -- > ubuntu-studio-users mailing list > [email protected] > Modify settings or unsubscribe at: > https://lists.ubuntu.com/mailman/listinfo/ubuntu-studio-users > -- MH mikeholstein.info <http://www.mikeholstein.info/>
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