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 -- ubuntu-studio-users mailing list [email protected] Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-studio-users
