David: My former optimism may have been misplaced.
I just tried it on Xubuntu 11.10, and have seen evidence that the problem exists there, too. I won't know for sure until I get everything downloaded & installed. - Aere On Sun, 2011-10-23 at 20:35 +0200, David Henningsson wrote: > On 2011-10-22 21:11, Aere Greenway wrote: > > FluidSynth Developers: > > > > In trying out FluidSynth on Ubuntu Linux 11.10 (Oneiric Ocelot), I > > encountered a serious degradation in sound generation (quality), and a > > much higher CPU usage than in the prior releases. > > > > The CPU-usage problem alone causes MIDI sequences that played fine on > > FluidSynth on a 1-gigahertz machine, to have many under-runs in JACK, on > > even a machine twice as fast. > > > > The sound generation problem doesn't appear as obviously, until you play > > sequences with many different tracks, and many notes playing together > > (which played well on Ubuntu 11.04, even on slower machines). > > > > What is happening, is that it sounds fine for the first few seconds, > > then from that point on, in many cases, new notes fail to play. For > > example, the oboe part may occasionally sound a note, but most of them > > are missing. Same thing for the flute part, and others. > > > > I noticed this immediately in trying out Ubuntu 11.10, because as a > > matter of course, I have found it to be a good idea to configure the > > polyphony parameter (Qsynth setup) to a value of 64, rather than the > > default of 256. I have been doing this to avoid JACK under-runs, playing > > the piano sound on FluidSynth with heavy (perhaps sloppy) sustain-pedal > > usage. > > > > When I set the polyphony value up to 256 (the default), the sequence > > that failed to play properly, sounded much better, but it was still bad. > > I had to set the polyphony parameter all the way up to 384 before it > > seemed to play the piece, but still sounded worse than on earlier > > releases. I suspect the reason for this, is that newer notes are being > > discarded instead of older notes (that faded, and are no longer sounding > > anyway). > > > > Of course, with the entire sound-generation 'table' full all the time > > (and with 6 times as many notes to be sounded by the processor), the CPU > > usage has shot up to levels where only my fastest machine can play it at > > all, where before, they played fine on a 1-gigahertz machine, and even > > on an 800 megahertz machine (with occasional under-runs). > > > > I experimented with this by setting the polyphony parameter down to 16 > > (the minimum allowed), and then playing notes, going up the keyboard > > from left to right. The notes were each held down for about 2 seconds, > > then I went to the next note. I did not use the sustain pedal. > > > > Several (some) notes past 16 notes, it seemed that most notes (every > > other note?) would play for maybe 1/4 second, then stop playing, even > > though the note was still depressed. > > > > I experimented with the sustain pedal, and things seemed actually to > > work better when using it, though I can't definitively say how. > > > > My suspicion is (and it is only speculation) that complex code for > > dropping the oldest notes from the sound-generation 'table' has been > > removed, hoping to reduce overhead, and some other scheme of removing > > the 'old' notes from being played has been substituted. This new scheme > > ends up with new notes being discarded in favor of notes already in the > > sound generation 'table', even though those old notes have already faded > > to an inaudible level. It also ends up requiring a much larger > > sound-generation 'table', and every note 'sounded' uses processor time. > > > > In the old version (Ubuntu 11.04, and prior), it seemed to remove the > > oldest notes (from the sound-generation 'table') in favor of the new > > notes. So if I set the polyphony level lower (64, or 48), it would sound > > great, and avoid under-runs, even on a slower machine. > > > > Could someone please comment on this? > > > > I have been relying on Qsynth/Fluidsynth (which has been extraordinarily > > reliable) as the basis of a major music education initiative, which I am > > (was) about to unveil. > > > > Everything still works fine using the Soundblaster card emu10k1 hardware > > synthesizer. But that isn't going to help you if you have a laptop. > > Qsynth/Fluidsynth is the component that is now failing, and with it > > failing, I cannot go forward to future Linux releases. > > > > Another work-around would be to use an external synthesizer, but the > > midisport-firmware package is no longer available in Ubuntu 10.10, so > > you can't even hook up your external synthesizer without a Soundblaster > > card (which you can't use on a laptop or half-high machine). > > Ubuntu 11.04 ships with FluidSynth 1.1.3 and Ubuntu 11.10 ships with > FluidSynth 1.1.4, so there are indeed differences in the engine. I can't > think of any that would cause a lot of difference in CPU usage, so > chances are the problem are in lower layers. Are you using the same > latency settings (which?) in both distributions? Would it be possible > for you to test either FS 1.1.4 on Ubuntu 11.04 or FS 1.1.3 on Ubuntu > 11.10 to ensure that the problem is in FS and not anywhere else? > > // David > -- Sincerely, Aere
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