Sorry to keep repeating this, but have you tried switching FluidSynth to linear interpolation yet? It seems a lot of your CPU usage is tied up in the 4-point interpolation that FluidSynth defaults to. -~Chris
On 11/23/2012 07:27 PM, Jan Newmarch wrote: > On Wed, 2012-11-21 at 16:26 +0100, David Henningsson wrote: > >> That is a very valid point; we might not strive to eliminate the average >> CPU as much as the worst-case CPU, even if both are important. >> >> Maybe you could run "perf top -d 1" and monitor that, to see if anything >> special happens while the CPU maxes out? > No luck :-(. The output looked the same for good and bad bits > >> I have another idea too; maybe we're trashing the L1 cache? If so, >> running with -z 1024 or -z 512 might give better result (combined with >> using floats instead of doubles). Here, -z 1024 gave better results, but >> not by much. The Raspberry Pi does not seem to have a L2 Cache (for CPU >> usage), so it might diff more for you. > Just setting -z to either 512 or 1024 and floats instead of doubles > didn't work by itself. > >> If we do an extremely rough calculation: We have a computer of 1 GHz, a >> sample rate of 50 kHz, and 100 voices; that gives us only 200 cycles per >> voice and sample. And we still have to do several floating point >> calculations every sample. So this leads me to believe that maybe there >> is no holy grail solution to this problem, nothing obvious we're missing >> that causes this CPU usage. Maybe it's more of trying one thing here and >> another thing there. > Sorry to pull in the "competition" here... Timidity gives CPU usage of > around 70-90% on nightsin.kar. But it doesn't have the blowouts to above > 100%, and plays okay (just). I don't know what the default settings are > for Timidity though. Maybe it is just fine tuning, although Aere is > getting good results on a slower CPU. > > On another tangent, running Fluidsynth as a server to the ALSA MIDI > sequencer alsa_seq plays okay with rate set to 22050. > _______________________________________________ fluid-dev mailing list fluid-dev@nongnu.org https://lists.nongnu.org/mailman/listinfo/fluid-dev
