MusicXML import of common and cut time is too strict

[lvinken]

Issue type

Import/export issue

Bug description

The time signature with common symbol is imported only when the signature is 4/4, cut when 2/2. This is overly strict. In case common or cut is not recognized, the time signature is ignored and the nominal measure duration will be set to 4/4, which may be incorrect. See determineTimeSig() in files importmxmlpass1.cpp and importmxmlpass2.cpp.

Steps to reproduce

1. import attached file Time_sig_common_cut_4_2_MS420.zip

Screenshots/Screen recordings

No response

MuseScore Version

MuseScore unstable prerelease for 4.2.0

Regression

No.

Operating system

Ubuntu 22.04

Additional context

No response

[Jojo-Schmitz]

We have:

    // determine if timesig is valid
    if (beats == "2" && beatType == "2" && timeSymbol == "cut") {
        st = TimeSigType::ALLA_BREVE;
        bts = 2;
        btp = 2;
        return true;
    } else if (beats == "4" && beatType == "4" && timeSymbol == "common") {
        st = TimeSigType::FOUR_FOUR;
        bts = 4;
        btp = 4;
        return true;
    } else

Would this:

    if (timeSymbol == "cut") {
        st = TimeSigType::ALLA_BREVE;
    } else if (timeSymbol == "common") {
        st = TimeSigType::FOUR_FOUR;
    } else if (!timeSymbol.isEmpty() && timeSymbol != "normal") {
        LOGD("determineTimeSig: time symbol <%s> not recognized with beats=%s and beat-type=%s",
        qPrintable(timeSymbol), qPrintable(beats), qPrintable(beatType));         // TODO
        return false;
    }

    btp = beatType.toInt();
    QStringList list = beats.split("+");
    for (int i = 0; i < list.size(); i++) {
        bts += list.at(i).toInt();
    }

be sufficient and pass muster?

As #20197 (master), #20198 (4.2.0) are in very close proximity and such a change would cause merge conflicts, I might add that there.

[cbjeukendrup]

@Jojo-Schmitz I guess it would indeed be fine to include that in #20197 and #20198. That solution doesn't ensure that the time signature has correct measure length for those symbols (i.e. a whole note) but that's no hard requirement in MuseScore either, right?

[Jojo-Schmitz]

Well, not ensuring the 'correct' measure length is what this issue is all about ;-)

[cbjeukendrup]

Well there is a distinction between allowing 4/4 instead of 2/2 and allowing 3/8 instead of 2/2 :)

But yeah, I guess it's fine anyway.

[Jojo-Schmitz]

I guess this now allows allows for the just removed CUT_TRIPLE, 9/8

[lvinken]

Wrt Jojo's proposed code, I do agree but would recommend removing the "with beats=%s and beat-type=%s" part from the LOGD, as it is no longer relevant.

Note that MuseScore's GUI allows setting the time signature symbol to common or cut for any time signature, without affect measure duration. E.g. you can create a 3/4 measure with time signature symbol common (whether that makes sense is different question). Why would the MusicXML importer be more restrictive ? In case of doubt, beats and beat type are more likely to be correct thatnthe symbol. See https://musescore.org/en/node/356715 for a real example.

[Jojo-Schmitz]

Done