[fluid-dev] How to optimize Fluidsynth latency in Windows?

[EarMaster - Hans Jakobsen]

Hi,

 

I make the ear training program EarMaster and would like to include a softsynth with low latency that works right out of the box. Fluidsynth looks great for that!

The critical part for me is latency and I am currently trying to optimize it in Fluidsynth. For that I made a small test program that plays a sound when I click with the mouse (this is the way it would be used in EarMaster to play real-time sound).

I then use Reaper to record the sound of the mouseclick and the sound produced by Fluidsynth. With the waveform on the screen, I can measure the total delay.

 

The default value on Windows is Audio.periods=8 and Audio.Period-Size=512, which gives an unacceptable high measured latency (>100 ms).

I tried different settings for the parameters and found that the setting with lowest latency, that still produces fluid sound, is Audio.periods=26 and Audio.Period-Size=64. This gives a theoretical latency of 33.4 ms for the buffers and I measured the total latency to about 80 ms.

 

This is still too much. How can I reduce the latency on Windows?

(I did see the Wiki about Latency, but it focuses only on Linux)

 

Are there better combinations of periods and Period-Size? - or other parameters I can adjust?

 

I believe some of the latency is caused by the use of Directsound, but what are the alternatives?

I see that ASIO support is not yet implemented, but how much improvement can I expect from ASIO compared to the 80 ms with DirectSound?

 

 

Best regards,

Hans Jakobsen