MuseScore: MIDI Output Bug With Unison Voices

by SLV Team 46 views

Hey guys! Ever run into a snag where your MIDI output in MuseScore goes haywire when you've got two voices singing the same note? Well, you're not alone! This article dives deep into a peculiar issue reported in MuseScore where unison notes in two voices cause the MIDI export to produce incorrect note durations. Let's break down the problem, explore the steps to reproduce it, and see what might be causing this funky behavior.

Understanding the Issue

So, what's the deal? Imagine you're working on a score with multiple instrument parts. You've got this awesome melody going, and in one of the parts, you decide to add some depth by using two voices. Now, when these voices hit a unison note (that is, they're playing the same note at the same time), followed by notes that are not in unison, the MIDI export of that part seems to get confused. Instead of the unison note having the correct duration, it gets extended, messing up the timing and feel of your piece. The expected behavior, of course, is that the MIDI export should accurately reflect the notes and their durations as they appear in the original score.

Specifically, the unison note gets continued after the note should have ended. The expected behavior is to have same notes in original score and in MIDI. This can be super frustrating, especially when you're trying to collaborate with other musicians or use your MIDI file in other software. You end up with a MIDI file that doesn't quite match your score, leading to confusion and extra work to fix the discrepancies.

Steps to Reproduce the Bug

Okay, let's get our hands dirty and see how to recreate this bug. Follow these steps, and you should be able to observe the issue yourself:

  1. Create a Score: Fire up MuseScore and create a new score with at least two instrument parts. This sets the stage for our experiment.
  2. Enter Notes in Two Voices: In the second instrument part, input notes using two different voices. Make sure that at least one of the notes is a unison note, followed by notes that are not in unison. This is where the magic (or rather, the bug) happens.
  3. Export to MIDI: Select the second instrument part and export it to MIDI format. This is the step where MuseScore translates your score into a MIDI file.
  4. Inspect the MIDI File: Open the exported MIDI file in a MIDI editor or a DAW (Digital Audio Workstation). Check the duration of the unison note. You should notice that it's longer than it should be, extending beyond its intended end point. This confirms the presence of the bug.
  5. Observe the Discrepancy: Compare the notes in the MIDI file with the original score in MuseScore. You'll see that the unison note in the MIDI file doesn't match the duration specified in the score.

By following these steps, you can reliably reproduce the MIDI output issue with unison voices in MuseScore.

Visualizing the Problem: Screenshots

To give you a clearer picture, here are some screenshots that illustrate the issue. The first image shows a simple score with two instrument parts. The second and third images show the MIDI export of the second instrument only and the MIDI export of the main score, respectively. Notice how the unison note's duration differs between the original score and the MIDI exports.

  • Original Score: The score shows the correct note durations for both voices, including the unison note.
  • MIDI Export (Second Instrument): The MIDI export of the second instrument shows the extended duration for the unison note.
  • MIDI Export (Main Score): Interestingly, exporting the entire score to MIDI seems to shorten the duration of the unison note, although it's still not entirely accurate.

These visual aids should help you understand the discrepancy between the score and the MIDI output.

Technical Details and Context

It's important to note the specific version of MuseScore Studio where this issue was observed. The bug was reported in MuseScore Studio version 4.6.2-252830930, running on macOS Sequoia (15.7) with an arm64 architecture. This information can be helpful for developers to pinpoint the exact code version where the bug might have originated.

Interestingly, the behavior differs depending on whether you export the individual instrument part or the entire score to MIDI. When exporting the main score, the unison note gets shortened, while exporting the instrument part results in an extended duration. This suggests that the MIDI export process handles unison notes differently depending on the context.

Furthermore, it appears that the extended duration note only occurs when there is a part ABOVE the instrument part with the two voices in unison. This adds another layer of complexity to the issue, indicating that the bug might be related to how MuseScore processes the vertical arrangement of instruments.

Potential Causes and Workarounds

So, what could be causing this issue? While we can't say for sure without diving into the MuseScore source code, here are a few educated guesses:

  • MIDI Event Handling: MuseScore might be incorrectly handling the MIDI events for note-on and note-off messages when unison notes are involved. The timing of these events could be slightly off, leading to the extended duration.
  • Voice Management: The way MuseScore manages voices internally could be contributing to the problem. The software might be getting confused about which voice is responsible for the unison note, leading to incorrect duration calculations.
  • Instrument Arrangement: The position of the instrument part in the score (i.e., whether it's above or below other parts) seems to influence the behavior. This suggests that the MIDI export process might be considering the arrangement of instruments when determining note durations.

Unfortunately, there's no simple workaround for this issue. However, here are a few things you can try:

  • Manual Correction: After exporting the MIDI file, manually adjust the duration of the unison notes in a MIDI editor or DAW. This is a tedious process, but it can ensure that the MIDI file accurately reflects your score.
  • Experiment with Voices: Try using different voice combinations or re-arranging the notes in the voices. In some cases, this might trick MuseScore into producing the correct MIDI output.
  • Export the Entire Score: As mentioned earlier, exporting the entire score to MIDI seems to shorten the duration of the unison notes. While this isn't ideal, it might be a better alternative than having extended durations.

Conclusion

The MIDI output issue with unison voices in MuseScore is a quirky bug that can cause frustration for musicians and composers. By understanding the steps to reproduce the bug, examining the visual evidence, and considering the technical details, we can gain a better appreciation for the problem. While there's no easy fix, the workarounds mentioned above might help you mitigate the issue until a proper solution is implemented in MuseScore.

Keep an eye on future MuseScore updates, as the developers are constantly working to improve the software and address bugs like this one. In the meantime, happy composing, and may your unison notes always sound as intended!