Path: csiph.com!eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail From: Folderol Newsgroups: comp.sys.raspberry-pi Subject: Re: RT Kernel Date: Sat, 9 Jan 2021 10:05:11 +0000 Organization: A noiseless patient Spider Lines: 45 Message-ID: <20210109100511.770dce5a@devuan> References: <20210107172620.1601ea0c@devuan> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Injection-Info: reader02.eternal-september.org; posting-host="5bb6329bfa5be3e3b041603789643532"; logging-data="19444"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+8T24nAMAnI3h34/c+vg2ocLhwUb0348I=" Cancel-Lock: sha1:gLmrHB083ulg+kWynbBHHtaQhZ0= X-Newsreader: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Xref: csiph.com comp.sys.raspberry-pi:25646 On Fri, 8 Jan 2021 23:38:47 +0000 (UTC) not@telling.you.invalid (Computer Nerd Kev) wrote: >Folderol wrote: >> Does anyone know if it is reasonably easy to get an RT kernel running on the Pi? >> I'm using devuan beowulf to get a small footprint install *without* either >> systemd or pulseaudio. >> >> Actually, this is already better than the official OS when running purely with >> ALSA. > >You don't say what you're actually doing. I gather that it's some >software audio synth, and I don't know anything about that >application. I'm guessing it's probably existing Linux software >though, so suggestions such as building for bare-metal or another >OS are presumably not worthwhile. > >There's a lot of info here, though not Pi-specific. Setting CPU >frequency scaling to "performance" was important for my application >(I also needed to disable video output on HDMI/Composite): >https://wiki.linuxaudio.org/wiki/system_configuration > >Real-Time patches for the Linux Kernel: >PREEMPT_RT: https://wiki.linuxfoundation.org/realtime/start >Xenomai >RTAI > >There is a PREEMPT_RT patched Linux distro for the Pi (this one >worked alright for me on a Pi Zero and seems to be fairly actively >developed, there might be others that I've forgotten about): >https://guysoft.wordpress.com/2017/10/09/realtimepi/ Thanks for all this further information. It is indeed a software synthesiser, but a very unusual one. Whereas most of these either work on sound samples, or previously generated wavetables, Yoshimi creates everything on-the-fly from mathematical formulae. These can make dynamic changes within individual cycles, resulting in incredibly rich sounds. I do quite a lot of work on the overall structure but don't touch these sound 'engines' - I leave that to those with far better understanding or the mathematics! -- W J G