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Round tempo to 2 decimal places in MusicXML export
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Since MuseScore internally stores tempo in units of 'beats per seconds'
and truncates it to a fixed precision, the exported MusicXML tempo
was sometimes incorrectly rounded. For example, 92 BPM in MuseScore
was exported as 91.9998 and 88 BPM was exported as 88.0002.

To eliminate this error, tempo is now rounded to up to 2 decimal places
when exporting. Since the MuseScore interface itself only allows up to
2 decimal places (in the Inspector), this is not expected to limit any
users.
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@matangover @vpereverzev
matangover authored and vpereverzev committed Feb 4, 2021
1 parent 996eb7d commit 73e60ea
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Showing 6 changed files with 275 additions and 2 deletions.
6 changes: 5 additions & 1 deletion importexport/musicxml/exportxml.cpp
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Expand Up @@ -3959,7 +3959,11 @@ void ExportMusicXml::tempoText(TempoText const* const text, int staff)

if (staff)
_xml.tag("staff", staff);
_xml.tagE(QString("sound tempo=\"%1\"").arg(QString::number(text->tempo()*60.0)));
// Format tempo with maximum 2 decimal places, because in some MuseScore files tempo is stored
// imprecisely and this could cause rounding errors (e.g. 92 BPM would be saved as 91.9998).
qreal bpm = text->tempo() * 60.0;
qreal bpmRounded = round(bpm * 100) / 100;
_xml.tagE(QString("sound tempo=\"%1\"").arg(QString::number(bpmRounded)));
_xml.etag();
}

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2 changes: 1 addition & 1 deletion mtest/musicxml/io/testDirections2.xml
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Expand Up @@ -100,7 +100,7 @@
<words font-weight="bold" font-size="12">Andante</words>
</direction-type>
<offset>-3</offset>
<sound tempo="91.9998"/>
<sound tempo="92"/>
</direction>
</measure>
<measure number="3">
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184 changes: 184 additions & 0 deletions mtest/musicxml/io/testTempoPrecision.mscx
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@@ -0,0 +1,184 @@
<?xml version="1.0" encoding="UTF-8"?>
<museScore version="3.02">
<programVersion>3.6.0</programVersion>
<programRevision>5b046ab</programRevision>
<Score>
<LayerTag id="0" tag="default"></LayerTag>
<currentLayer>0</currentLayer>
<Division>480</Division>
<Style>
<pageWidth>8.27</pageWidth>
<pageHeight>11.69</pageHeight>
<enableVerticalSpread>1</enableVerticalSpread>
<Spatium>1.74978</Spatium>
</Style>
<showInvisible>1</showInvisible>
<showUnprintable>1</showUnprintable>
<showFrames>1</showFrames>
<showMargins>0</showMargins>
<metaTag name="arranger"></metaTag>
<metaTag name="composer">Composer</metaTag>
<metaTag name="copyright"></metaTag>
<metaTag name="creationDate">2021-01-17</metaTag>
<metaTag name="lyricist"></metaTag>
<metaTag name="movementNumber"></metaTag>
<metaTag name="movementTitle"></metaTag>
<metaTag name="platform">Apple Macintosh</metaTag>
<metaTag name="poet"></metaTag>
<metaTag name="source"></metaTag>
<metaTag name="translator"></metaTag>
<metaTag name="workNumber"></metaTag>
<metaTag name="workTitle">Title</metaTag>
<Order id="orchestral" customized="1">
<name>Orchestral</name>
<instrument id="piano">
<family id="keyboards">Keyboards</family>
</instrument>
<section id="woodwind" brackets="true" showSystemMarkings="true" barLineSpan="true" thinBrackets="true">
<family>flutes</family>
<family>oboes</family>
<family>clarinets</family>
<family>saxophones</family>
<family>bassoons</family>
<unsorted group="woodwinds"/>
</section>
<section id="brass" brackets="true" showSystemMarkings="false" barLineSpan="true" thinBrackets="true">
<family>horns</family>
<family>trumpets</family>
<family>cornets</family>
<family>trombones</family>
<family>tubas</family>
</section>
<section id="timpani" brackets="true" showSystemMarkings="false" barLineSpan="true" thinBrackets="true">
<family>timpani</family>
</section>
<section id="percussion" brackets="true" showSystemMarkings="false" barLineSpan="true" thinBrackets="true">
<family>keyboard-percussion</family>
<family>drums</family>
<family>unpitched-metal-percussion</family>
<family>unpitched-wooden-percussion</family>
<family>other-percussion</family>
</section>
<family>keyboards</family>
<family>harps</family>
<family>organs</family>
<family>synths</family>
<section id="plucked-strings" brackets="true" showSystemMarkings="false" barLineSpan="true" thinBrackets="true">
<family>plucked-strings</family>
</section>
<soloists/>
<section id="voices" brackets="true" showSystemMarkings="false" barLineSpan="false" thinBrackets="true">
<family>voices</family>
</section>
<section id="strings" brackets="true" showSystemMarkings="true" barLineSpan="true" thinBrackets="true">
<family>orchestral-strings</family>
</section>
<unsorted/>
</Order>
<Part>
<Staff id="1">
<StaffType group="pitched">
<name>stdNormal</name>
</StaffType>
</Staff>
<trackName>Piano</trackName>
<Instrument id="piano">
<longName>Piano</longName>
<shortName>Pno.</shortName>
<trackName>Piano</trackName>
<minPitchP>21</minPitchP>
<maxPitchP>108</maxPitchP>
<minPitchA>21</minPitchA>
<maxPitchA>108</maxPitchA>
<instrumentId>keyboard.piano</instrumentId>
<clef staff="2">F</clef>
<Articulation>
<velocity>100</velocity>
<gateTime>95</gateTime>
</Articulation>
<Articulation name="staccatissimo">
<velocity>100</velocity>
<gateTime>33</gateTime>
</Articulation>
<Articulation name="staccato">
<velocity>100</velocity>
<gateTime>50</gateTime>
</Articulation>
<Articulation name="portato">
<velocity>100</velocity>
<gateTime>67</gateTime>
</Articulation>
<Articulation name="tenuto">
<velocity>100</velocity>
<gateTime>100</gateTime>
</Articulation>
<Articulation name="marcato">
<velocity>120</velocity>
<gateTime>67</gateTime>
</Articulation>
<Articulation name="sforzato">
<velocity>150</velocity>
<gateTime>100</gateTime>
</Articulation>
<Articulation name="sforzatoStaccato">
<velocity>150</velocity>
<gateTime>50</gateTime>
</Articulation>
<Articulation name="marcatoStaccato">
<velocity>120</velocity>
<gateTime>50</gateTime>
</Articulation>
<Articulation name="marcatoTenuto">
<velocity>120</velocity>
<gateTime>100</gateTime>
</Articulation>
<Channel>
<program value="0"/>
<synti>Fluid</synti>
</Channel>
</Instrument>
</Part>
<Staff id="1">
<VBox>
<height>10</height>
<Text>
<style>Title</style>
<text>Title</text>
</Text>
<Text>
<style>Composer</style>
<text>Composer</text>
</Text>
</VBox>
<Measure>
<voice>
<TimeSig>
<sigN>4</sigN>
<sigD>4</sigD>
</TimeSig>
<Tempo>
<tempo>1.46666666666667</tempo>
<followText>1</followText>
<text><b></b><font face="ScoreText"/><b><font face="Edwin"/> = 88</b></text>
</Tempo>
<Rest>
<durationType>measure</durationType>
<duration>4/4</duration>
</Rest>
</voice>
</Measure>
<Measure>
<voice>
<Tempo>
<tempo>1.53333</tempo>
<text>Andante</text>
</Tempo>
<Rest>
<durationType>measure</durationType>
<duration>4/4</duration>
</Rest>
</voice>
</Measure>
</Staff>
</Score>
</museScore>
83 changes: 83 additions & 0 deletions mtest/musicxml/io/testTempoPrecision_ref.xml
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE score-partwise PUBLIC "-//Recordare//DTD MusicXML 3.1 Partwise//EN" "http://www.musicxml.org/dtds/partwise.dtd">
<score-partwise version="3.1">
<work>
<work-title>Title</work-title>
</work>
<identification>
<creator type="composer">Composer</creator>
<encoding>
<software>MuseScore 0.7.0</software>
<encoding-date>2007-09-10</encoding-date>
<supports element="accidental" type="yes"/>
<supports element="beam" type="yes"/>
<supports element="print" attribute="new-page" type="no"/>
<supports element="print" attribute="new-system" type="no"/>
<supports element="stem" type="yes"/>
</encoding>
</identification>
<part-list>
<score-part id="P1">
<part-name>Piano</part-name>
<part-abbreviation>Pno.</part-abbreviation>
<score-instrument id="P1-I1">
<instrument-name>Piano</instrument-name>
</score-instrument>
<midi-device id="P1-I1" port="1"></midi-device>
<midi-instrument id="P1-I1">
<midi-channel>1</midi-channel>
<midi-program>1</midi-program>
<volume>78.7402</volume>
<pan>0</pan>
</midi-instrument>
</score-part>
</part-list>
<part id="P1">
<measure number="1">
<attributes>
<divisions>1</divisions>
<key>
<fifths>0</fifths>
</key>
<time>
<beats>4</beats>
<beat-type>4</beat-type>
</time>
<clef>
<sign>G</sign>
<line>2</line>
</clef>
</attributes>
<direction placement="above">
<direction-type>
<metronome parentheses="no">
<beat-unit>quarter</beat-unit>
<per-minute>88</per-minute>
</metronome>
</direction-type>
<sound tempo="88"/>
</direction>
<note>
<rest measure="yes"/>
<duration>4</duration>
<voice>1</voice>
</note>
</measure>
<measure number="2">
<direction placement="above">
<direction-type>
<words font-weight="bold" font-size="12">Andante</words>
</direction-type>
<sound tempo="92"/>
</direction>
<note>
<rest measure="yes"/>
<duration>4</duration>
<voice>1</voice>
</note>
<barline location="right">
<bar-style>light-heavy</bar-style>
</barline>
</measure>
</part>
</score-partwise>
1 change: 1 addition & 0 deletions mtest/musicxml/io/tst_mxml_io.cpp
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Expand Up @@ -195,6 +195,7 @@ private slots:
void tempo3() { mxmlIoTestRef("testTempo3"); }
void tempo4() { mxmlIoTestRef("testTempo4"); }
void tempoOverlap() { mxmlIoTestRef("testTempoOverlap"); }
void tempoPrecision() { mxmlMscxExportTestRef("testTempoPrecision"); }
void textLines() { mxmlMscxExportTestRef("testTextLines"); }
void timesig1() { mxmlIoTest("testTimesig1"); }
void timesig3() { mxmlIoTest("testTimesig3"); }
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1 change: 1 addition & 0 deletions mtest/musicxml/io/updateReference
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Expand Up @@ -29,3 +29,4 @@ cp $S/testTablature3.xml testTablature3.xml
cp $S/testTablature4.xml testTablature4.xml
cp $S/testTablature5.xml testTablature5_ref.xml
cp $S/testBeams3.xml testBeams3_ref.xml
cp $S/testTempoPrecision.xml testTempoPrecision_ref.xml

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