Hi,
2012/5/1 Grant Diffey gdiffey@gmail.com:
I can't seem to get below 512frames in flight (2 256sample frames or 4 128 or 8 64's) without consistant overruns.
at least at 44.1 and 48 kHz I can get it to run without consistent xruns with 3 periods/buffer and 128 frames/period. For 88.2 and 96 kHz I need to go to 4 periods/buffer. Less than 128 frames/period lead to consistent xruns no matter how many periods/buffer I use.
I've been using a kernel freshly cloned from Tiwai's git with the latest rt patch on a rather slow laptop. I've switched to Fedora on that machine a couple of days ago so I don't know yet if my system settings are properly adjusted for Jack, yet.
This leads to rather high latencies (22ms+) or is this conclusion bogus?
Yes, I guess that this conclusion is bogus.
First, even at 44.1 kHz I think that you rather get 11.6 ms latency (512/44.1). At 96 kHz this reduces to 5.3 ms.
I've even done some measurements using jack_iodelay. At 96 kHz I get a total round trip latency of 17.5 ms. According to the jack_iodelay manpage this corresponds (if I get it right) to an hardware input/output latency of the device of ~584 frames (6.1 ms).
This would lead to the (maybe bogus) conclusion that we have a total output latency of 11.4 ms.
By the way, if you're using jack2 you would probably want to start it in synchronous mode (with the -S option ). Otherwise you get an implicit extra period/buffer. (I guess you already know that.)
@Daniel: I could not find any difference between my latest "old-streaming-logic" kernel and my latest "new-streaming-logic" kernel.
Regards,
Felix