Re: [linux-audio-dev] Re: jack, low latency and IO

On Tuesday 07 December 2004 15:42, Artem Baguinski wrote: You do realize that you can't react immediately regardless. Jack - and all other audio API's process audio in chunks/periods/buffers whatever they are called. So it depends on how much jitter you tolerate in the response. This is determined by the period size in the simple case of handling input as soon as possible (which is the next call to your process callback) Which is the easy thing and if you are able to run low latency kernels you can use with it with some kinds of controls. And in this case as long as the event gets there by the next process cycle you're ok. Or you need to add timestamping on incoming events with respect to the position of the audio-playback-pointer in the current period Then you delay them by the same amount in the next available process cycle. You increase response time but you decrease jitter. But then you need accurate and quick-as-possible response for those incoming events and this is the situation Paul mentioned, where it gets complicated. An solution for a custom hw interface could to use an audio input on the sound card as a trigger/control input. Then you can just deal with it in your process cycle. But then most audio interfaces don't like dc signals so you have careful what you send in. Just so you know why it is complicated :) G -- electronic & acoustic musics-- http://www.xs4all.nl/~gml