On Wed, 17 Jan 2018 20:21:55 -0500 Tim <termtech@xxxxxxxxxx> wrote: >On 01/17/2018 08:04 PM, Paul Davis wrote: >> >> >> On Wed, Jan 17, 2018 at 7:37 PM, Tim <termtech@xxxxxxxxxx >> <mailto:termtech@xxxxxxxxxx>> wrote: >> >> >> >> On 01/17/2018 06:58 PM, Will Godfrey wrote: >> >> I'm getting a little confused when comparing our (Jack) buffer >> sizes with those >> discussed on Windows, Mac and general music groups. >> >> These latter never mention periods at all, and it's always >> frames per buffer, >> so when trying to make comparisons should I take buffers as 1:1 >> or should I be >> comparing their buffers to our periods? >> >> >> Hi Will. >> >> From memory on Windows years ago, and if I understand Jack correctly, >> Jack, or more specifically ALSA (in this case let's say using the >> ALSA driver), puts you much lower-level towards the sound hardware. >> >> >> while true, this is not necessarily a benefit. >> >> the better design here is to completely decouple everything as much as >> possible from device interruptsm and use DLL's to provide sub-sample >> accurate "prediction" of where an application can read and write at any >> time. > >Ha! Yeah I remember experimenting with that sort of thing. >Like you're in a race with the DMA pointers. Nice we could read them. > >> this allows you to have multiple applications using different buffer >> sizes (different latency), and to get better latency than the device's >> inherent interrupt intervals would allow. > >I've mused a few times about whether it would be possible to do > this with Jack midi when using large Jack buffer sizes ;-) >It's ironic because MusE supports both Jack midi (at say 2048 buffer) > and ALSA midi (with say 1024 Hz timer) at the same time. > >> it's what coreaudio does, and ALSA should do it too. i doubt if it ever >> will. pulse sort of does this, but all in user space. > >How might sample rate conversion fit into this? Does it make it easier? >Or no difference, they might slap it on ahead of or after this layer? >So that say, we might not need the ALSA mixing layer (I forget what > it's called, dmix?). > >T. Very interesting info here, but I'm trying to understand a scenario where you'd want different latencies within a single environment. -- Will J Godfrey http://www.musically.me.uk Say you have a poem and I have a tune. Exchange them and we can both have a poem, a tune, and a song. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx https://lists.linuxaudio.org/listinfo/linux-audio-user
