public void Play(byte channel, byte program, byte note, byte velocity)
 {
     if (CHANNEL < channel)
     {
         return;
     }
     if (s_last_program[channel] != program)
     {
         s_device.ProgramChange(channel, program);
         s_last_program[channel] = program;
     }
     s_device.Play(channel, note, velocity);
 }