At Thu, 29 Mar 2007 17:46:38 +0800, Carlo Florendo wrote: > > Good Day! > > After studying the intricacies of MIDI, I ended up writing an > implementation of the MIDI protocol and file format. > > I then studied the ALSA sequencer API to be able to control a synthesizer > keyboard and play MIDI files. I've used aplaymidi, aconnect, arecordmidi, > and all those great ALSA utilities. They're very good! > > However, I wanted to have a simple ncurses based, command line MIDI > sequencer meant for small Linux distributions such as DSL or Trustix so I > began to write a command line sequencer using ALSA. I've encountered one > problem about using usleep() and nanosleep() especially in 2.4 kernels. You cannot get a small sleep usually on user-space processes. Usually, usleep() is implemented with select/poll and its timeslice is defined by HZ in kernel config. In most cases, it's HZ=100, 250 or 1000 while 2.4-i386 kernel supports only HZ=100. That is, the least sleep time is 10ms no matter what value you pass to usleep(). This can be overcome by using a realtime schedule class and priority like JACK does. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
