Key signature in "master" track of MIDI file is ignored

As discussed on the forum, my belief is the problem is that the MIDI file fails to include the key signature in the track containing the data, Different tracks can potentially have different key signatures, so MuseScore is most likely not looking at one track to determine the key signature for another. Even though it seems it would be better if the MIDI file did contain the key signature with the actual track it applies to, apparently there are MIDI files out there that don't do this, and in such cases, probably we should consider the initial key signature to apply to all tracks.

Master-Track (or Control-Track or Tempo Track) has been used by industry-leading companies such as Rol4nd and yamah4 for years. I have worked with hardware and software sequencers (sound recording studios) for years.

Master-Track works like System elements in Musescore. It's unnecessary to write this information in each track because this information is global. Also, the MIDI-file interpreter doesn't calculate tempo (time-sig, etc) separately for each track.

See: https://acad.carleton.edu/courses/musc108-00-f14/pages/03/03StandardMID…
(From MMA's "Complete MIDI 96-1-3" specification; with advanced examples)

Example: Suppose you do ritardando (ie decrease the tempo) you don't write this information on each of the 16 tracks. you just write on the Master-track (first track of the SMF Type1).
Or you have made permanent modulation from one key to the other. you don't write such information on all tracks, you just write on the Master track.
Or you switched from 4/4 pace to 6/8. You don't want to write this on all 16 tracts individually. You just write on the Master track.
Or Marker events (like "Section A", "Bridge", "Intro", "Final", etc) ...

Can you understand the logic?

Some sequencer software automatically carries this information to the Master / Control /Tempo track, regardless of which track it is on, some software will alert you, and the remaining software will ignore this information silently. Note: Since some DAW's keep Audio, MIDI and VST separately, it may be correct to provide track-based information on them, but this is not an SMF implementation.

(copied from the forum, since I was that first; probably best to continue discussion here only)

Yes, I am aware there is convention used by many to have a master track. Some use it only for tempo and time signature changes, and there I absolutely see the value. It's much less clear why this same model should be used for key signatures, though., but some apparently some implementations do this. I'm not aware of anything in the MIDI spec that actually calls for or otherwise sanctions this, but I'm not an expert. So I certainly wouldn't be the one trying to change our own implementation. I'm just trying to help people see how they actually can create MIDI files that work as expected, by embedding key signature information the way we expect it.

I would think that any software that was written first and foremost to help you edit MIDI data would provide controls for this, just as software like MuseScore that was written first and foremost to help you edit notation data provides system vs staff text etc. But maybe there exist some sequencers that lack this control, just as there are presumably some notation programs that lack the concept of "system text". So, we should indeed be prepared to handle output of such programs. But again, I'm not the expert, I'm not the one who could implement this. I'm just the one trying to help users achieve the desired goal today, using the tools we have.

I categorized this a suggestion because we do currently handle input that is formatted the way we expect, and indeed the vast majority of MIDI files I have ever seen in the wild are formatted this way. It's a suggestion that we also handle MIDI files that are formatted in a different way. I agree with the suggestion.

I'm confused, why would you be using two OMR programs as examples in a discussion of MIDI? that's not really their native language either - MusicXML is. Why not just export MusicXML from programs that understand notation? MIDI is more for programs that don't have a concept of notation, like sequencers.

Anyhow, as I have said repeatedly, I'm not enough of a MIDI expert to say what exactly is going on, what I do know is the vast majority of MIDI files imported into MuseScore - files which usually come from sequencers, not OMR or notation programs - work just fine. I have hundreds I've collected from various sources over the years, some posted the forums as part of some other support question, some downloaded to illustrate some musical point or other, only once or twice have I seen this go wrong.

Attached is literally the first one I grabbed just now, from https://www.mfiles.co.uk/classical-midi.htm. Maybe you can tell me if there is something different about how it's formatted or if we just happen to be guessing correctly.

I'll be curious what you learn after examining this file! As I said, normally we do use the supplied key signature, but I think this particular file just happens to store it in a place we don't expect.

To clarify something about formats: MIDI was never ever designed to record information about music notation, and is lacking in some really fundamental ways in that regard. For instance, it has no way of recording the distinction between G# and Ab, or the difference between a staccato quarter note and a sixteenth notes, or the fact that a passage was marked with accent marks or a slur, or any number of really basic things like that. This is why MusicXMl exists - to actually record all that information. So even if the key signature issue were straightened out, using MIDI will lose a ton of essential information after scanning a score. That's why programs like the ones you mention are really designed primarily for MusicXML. That format records all the information I mentioned and more. The difference between the results you get after importing a MIDI file versus importing MusicXMl are like night and day. Because it is so limited, MIDI is something one normally relies on only if one doesn't have access to MusicXML. But if you are scanning to software that understands MusicXML, it's absolutely the immensely superior format for then importing into notation software like MuseScore. Export MIDI to to get a quick-and-dirty sense of the playback,a nd as you mention, maybe play around with tempo etc, but all that stuff and tons more is doable in notation software, and it will all work much better working from MusicXML.

The thing to do is simple: If there is a key-sig in Master-Track, the software will first consider it.
If there are key-sig (s) in musical tracks, it will process them secondaryly.
Thus, both problems are solved at once. No need to be an expert. :)

Knowing that the context here is offering MIDI files does help explain why you aren't using MusicXML, so thanks for that additional info :-). Still, I would say if you are concerned with people being able to create notation from the files you provide, you definitely should strongly consider offering MusicXML files in the future. They take no more effort to create than MIDI but are definitely much better for the purposes of getting good notation. But that doesn't help for the MIDI files you have already.

I think you are right that the algorithm used to detect key is likely to work better for tonal than modal music. FWIW, according to the comments in the source code, the algorithm used comes from "Inferring Score Level Musical Information From Low-Level Musical Data", 2004, by Jürgen Kilian.

Anyhow, hopefully someone who understands both the structure of MIDI files and the structure of the MIDI import algorithms in the MuseScore source code can look at implementing this suggestion in the future. Unfortunately, this does indeed require more expertise than I possess.

It is not a bug, just something not yet coded, so Suggestion is just fine

We categorize issues for good reasons, to help with tracking. The priority of an issue is not necessarily related to whether it is considered a bug or suggestion, and it is counteproductive to miscategorize something in an a effort to increase its priority.

I’m attaching a P1 priority to this, doesn’t guarantee anything because it’s still a question of whether some volunteer chooses to implement the feature or not, but at least it shows up with other P1 issues near the top of the heap.

But for record - not that it matters - if someone can show where in the MIDI spec it actually says it is correct and necessary for MIDI files to omit key signature info in the tracks themselves, then it will be completely proper to co sided this a bug rather than a suggestion. but again, that’s not really an important distinction at this point in terms of prioritization.