Hi, At Mon, 3 Dec 2001 15:59:23 +0200 (EET), Timo Tossavainen wrote: > > > Hi, > > I've been developing a simple realtime bassline softsynth (osc, adsr, lp > filter) for ALSA (controlled using midi ports in alsa sequencer). The idea > is to ultimately build a system that allows one to connect MIDI controlled > virtual devices using cables. I'm hoping that I can skip writing a > sequencer and use an external one (written by someone else). > > The simple synth is currently working pretty well with 2x128 samples of > buffering and using snd_pcm_writei to write the samples (takes about 2% > cpu with my sincm blit bandlimited oscillators, no optimization on a > 450 Mhz machine) > > I've wrapped the parts of ALSA I'm using in C++ classes, which throw > exceptions at every error so I shouldn't miss a single one. > > The midi implementation reads a midi event by testing > snd_seq_event_input_pending and then using snd_seq_event_input to get the > event. > > Seems I have a number of problems with the ALSA sequencer (and MUSE > but I don't know if that's relevant) points 1 and 2 occur when > I'm just running the synth by itself and connect the keyboard > port to the synth with aconnect. > > 1) Playing frantically on the keyboard I sometimes get notes that are > impossible to play on the keyboard (e.g. key 3) without error. > The keyboard is a Roland PC-200 mk II. Did input buffer overflow happen? If this behavior appears, please check /proc/asound/seq/clients whether cell allocation failed.
> 2) Sometimes ALSA just plain crashes during playing, pcm seems to work but > I get no input from the sequencer (the sequencer just stops giving events) > After quitting the program even pcm stops working. I have to restart > the driver to get it working. This happens even when I'm just writing > zeroed data to the driver and dumping the midi events, no synth running, > just to rule out a bug in the synth. Hmm.. Possibly the same reason (overflow of event pool)? > 3) Running MUSE concurrently works fine when recording midi, playback > breaks my synth (running as root and SCHED_FIFO/REALTIME). Is it > possible it suspends the audio even when my synth supposedly owns > it ? I'd expect xruns but seems that something else happens (configured > so that it doesn't use audio ports at all). > > 4) The soundfont banks (.sf2) sound muffled (very low volume, all treble > gone) in MUSE but the older banks (.sbk) work. The .sf2-banks sound ok > when just using alsa (with aconnect) (This is probably a MUSE issue) Do both outputs come from the same client? Or do you refer to MusE's iiwsynth? > This is no biggie, but it seems that snd_seq_event_input returns 1 on > succesful read, not the number of bytes remaining as stated in > the doxygen documentation or maybe I misread the source. Oh, yes, the document must be fixed.. Thanks. Takashi _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
