At Wed, 21 Jan 2004 03:01:19 -0800, Andrew Morton wrote: > > > I just wanted to elaborate abit; -R in the argument line indicates that jack > > should be running SCHED_FIFO, and since there are no specific settings for > > period-size and number of periods, jack is probably defaulting to 2-periods > > and 1024 samples period size. 2.4 works rather reliably with period-sizes > > quite a bit smaller than that. I think 256 is commonly used, with good > > hardware+drivers I suppose you could go even lower. > > I don't know what these numbers mean... > > What does this transalate to in interval-in-milliseconds, and after how > many milliseconds delay will an underrun occur? > > And what else is happening on the system at the time? a few months ago before 2.6.0 was released, i tested the audio latency with different kernels. the result was shown in the internal conference in SUSE, and i totally forgot to release the data until now :) maybe it will show you other aspects. here you can find the slides http://www.alsa-project.org/~iwai/audio-latency.pdf some notes: - the red line of the graph is the buffer size - when the plot overcomes this line, the buffer underrun occurs, aka sound dropout. - performed on Athlon 2200+ / 256MB / SB live - the kernel tested at that time was slightly old, 2.6.0-test10, so the result with the latest kernel may differ. - suse 2.4 kernel runs with HZ=1000 and O(1) scheduler -- Takashi Iwai <tiwai@xxxxxxx> ALSA Developer - www.alsa-project.org
