On Sat, Dec 01, 2018 at 01:19:00PM -0600, Adam Thompson wrote: > PROBLEM STATEMENT: driving FluidSynth from a MIDI controller produces ~1/4sec > delay between keypress and sound. > [...]
> Is sndio(4) suitable for real-time(-ish) performance? Or do I need > a (OS) platform that does ASIO or JACK? (I mostly play by ear so > I'm targeting <<0.1sec latency.) Yes, sndiod is usable (actually designed for) low-latency usage. You need to change the sndiod buffer size to whatever your system can handle (depends on CPU, audio interface). I'd recommend to set in /etc/rc.conf.local sndiod_flags=-z240 Let us know how it works. If it works, you could try -z120, that's what I use on my machines. -z240 sets the block size to 240 samples, at 48000Hz sample frequency, this corresponds to 48000Hz / 240 = 5ms block. The total end-to-end latency is typically 3 blocks, so I'd get 5ms * 3 = 15ms. FWIW, for music, you shouldn't exceed few tenths of ms of latency. > > Dmesg follows, just in case anyone spots anything useful in there… > > Hardware setup, broadly: > * Dell Latitude E6430 laptop > - booting in EFI mode to work around a weird bootloader bug > * onboard azalia(4) audio (for now) using onboard speakers (for now) > * Roland A500PRO MIDI controller, connected via USB > * M-audio Uno USB-MIDI, nothing connected to it yet > * No-name USB 5.1ch Audio DAC from Amazon, nothing connected to it yet > - (leaving the M-audio umidi and the "ABC" uaudio devices disconnected > makes no difference) > The "ABC" USB devices are unlikely to work with small blocks, but there are fixes comming soon (hopefully).
