An early problem in Open Rails, and one which hung around for a bit, was an inability to play a short horn blast — something necessary for common horn signals, including the usual North American long-long-short-long pattern for grade crossings. The basic horn behavior was resolved fairly quickly, but there were still a significant number of horns & whistles that didn’t play correctly, instead playing out a full-length blast regardless. The issue was figured out in the community and resolved by editing or adding in cue points (where they were non-existant) in the sound effect .WAV files. That has been the standard fix for a large variety of horns that don’t play correctly in Open Rails. Unfortunately, there have still been a few “unfixable” ones that didn’t improve with editing the cue points in a sound editor.
The solution turns out to be a parameter in the .SMS file that determines how the horn sound is triggered and stopped.