Unison collisions fail in MS-created MP3's

• Apr 8, 2020 - 16:06
Reported version
3.4
Type
Functional
Frequency
Once
Severity
S3 - Major
Reproducibility
Always
Status
active
Regression
No
Workaround
Yes
Project

OS: macOS 10.15, Arch.: x86_64, MuseScore version (64-bit): 3.4.2.25137, revision: 148e43f

For the enclosed (simplest test case) score, "Export to MP3". The whole-note is cut off (clipped) by the quarter note, a "unison collision clipping". This problem was fixed for live playback from the score way back in MuseScore 2, but persists when MP3 output is produced, and, since the .com site works via MP3 production, all such scores posted to the site fail unless all unison collisions are located and hand-tweaked as they were before that fix (but that is now much more difficult because of the difference in behavior).

Apparently, some patches were posted and pulled/unpatched and maybe lost. @mirabilos (who was responsible for the patches) describes his understanding of the chronology on the discussion linked above.

Attachment Size
Unison_clash_test.mscz 3.73 KB

Comments

If it works for playback but not for MP3 export, then it probably has nothing to do with a PR being merged or not merged or revert at the wrong time. More likely just a matter of some subsequent (since when it was last know to work) having broken the code on the export side. Some of the code is of course shared between playback and export, but there are necessarily differences as well. Here's a case where it would be useful to know the last release in which MP3 export worked.

Sergei Shchetnikov experimented with other audio formats, and found that all except .mid fail in the same way.

Another user has posted a complaint to .com observing that "the score doesn't work when posted.". I pointed him back here, but that's no answer.