I'm making a conductor simulation for my project. To make a sound module, I have to modify the speed and volume of MIDI (while it is playing). I thought that it can be achieved by modifying mp3 file, but I found that the sound quality is degraded if I change the speed of it. Therefore, I have to deal with MIDI file itself.
Is there any good c++ library which supports playing and real-time modifying of the MIDI file?