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List:       lilypond-user
Subject:    Re: Export from LilyPond to MusicXML
From:       Thomas Morley <thomasmorley65 () gmail ! com>
Date:       2021-09-27 22:53:16
Message-ID: CABsfGyVUxFcSP9uLtA6u0zNSDw7bNDakH+0_uZWq9kRSDt0-fQ () mail ! gmail ! com
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Hi Jacques,

Am Mo., 27. Sept. 2021 um 00:48 Uhr schrieb Jacques Menu
<imj-muzhic@bluewin.ch>:
> 
> Hello folks,
> 
> The recent posts on this subject show there is interest in the matter. Sorry for \
> the length of this one...

Tbh, most of the mor detailed stuff is way over my head..
> 
> My work was initially homed by Grame's libmusicxml2 library as an example of what \
> it could be used for, in the lilypond branch at \
> https://github.com/grame-cncm/libmusicxml/tree/lilypond. 
> Dom Fober, the author and maintainer of libmusicxml2, and I decided some time ago \
> to separate things for practical reasons, and I now push to the GitHub repository I \
> created at https://github.com/jacques-menu/musicformats.

Good to know.

> I'm currenly finalizing version 1.0.0, which explains why the test and master \
> branches are not up to date - only the dev branch is currently. 
> The musicformats library is structured along the lines shown at page 16 in \
> https://github.com/jacques-menu/musicformats/blob/dev/doc/maintainersGuideToMusicFormats/maintainersGuideToMusicformats.pdf \
> (the users's guide is not yet ‘usable', sorry). 
> The central component of musicformats is MSR (Music Score Representation), from \
> which various formats can be obtained. 
> In this picture, we see that we could create MusicXML output from within the \
> LilyPond implementation going along the LilyPond - LPSR - MSR - MXSR  - MusicMXL \
> path. The missing part would be the creation of an LPSR (LilyPond Score \
> Representation), the others already exist. 
> As an example, the LPSR representation and LilyPond output produced by:
> 
> xml2ly basic/HelloWorld.xml -display-lpsr > LPSR_contents.txt 2>&1
> 
> are in the attached LPSR_contents.txt file.
> 
> The resulting score is:
> 
> 
> Jean and I have had discussions as to how the export to MusicXML could be tackled \
> on the LilyPond side, but nothing concrete yet. Some of the information needed is \
> readily accessible inside LilyPond, but grabbing the remaining part is not easy. 
> The musicformats repository contains examples using the library to create scores in \
> C++ applications, among them: 
> jacquesmenu@macmini: ~/musicformats-git-dev/files/musicxml > Mikrokosmos3Wandering \
> -a What Mikrokosmos3Wandering does:
> 
> This multi-pass generator creates a textual representation
> of Zoltán Kodály's Mikrokosmos III Wandering score.
> It performs various passes depending on the output generated.
> 
> Other passes are performed according to the options, such as
> displaying views of the internal data or printing a summary of the score.
> 
> The activity log and warning/error messages go to standard error.
> 
> jacquesmenu@macmini: ~/musicformats-git-dev/files/musicxml > Mikrokosmos3Wandering \
>                 -apropos generate
> --- Help for atom "generate" in subgroup "Generated output"
> -generate, -gen GENERATED_OUTPUT_KIND
> Generate GENERATED_OUTPUT_KIND code to the output.
> The 5 generated output kinds available are:
> braille, guido, lilypond, midi and musicxml.
> The default is 'LilyPond output'.
> 
> (midi output is actually not yet available, though)
> 
> For example, one can run:
> 
> jacquesmenu@macmini: ~/musicformats-git-dev/files/musicxml > Mikrokosmos3Wandering \
> -generate  musicxml  -o Mikrokosmos3Wandering.xml -trace=passes 
> %--------------------------------------------------------------
> Pass 1: Creating the MSR score with the functions
> %--------------------------------------------------------------
> *** MusicXML warning *** :91: The staffMeasuresSlicesSequence of staff \
>                 "Part_OnlyPart_Staff_One" is null
> *** MusicXML warning *** :91: The staffMeasuresSlicesSequence of staff \
> "Part_OnlyPart_Staff_Two" is null 
> %--------------------------------------------------------------
> Pass 2: Convert the MSR score into a second MSR
> %--------------------------------------------------------------
> 
> %--------------------------------------------------------------
> Pass 3: Translating the MSR into an MXSR
> %--------------------------------------------------------------
> 
> %--------------------------------------------------------------
> Pass 4: Convert the MXSR into MusicXML text
> %--------------------------------------------------------------
> 
> Opening file 'Mikrokosmos3Wandering.xml' for writing
> Warning message(s) were issued for input line 91
> 
> 
> This creates file Mikrokosmos3Wandering.xml, attached.
> 
> 
> The functionality of musicformats is available as API C++ functions. For example, \
> conversion from MusicXML data to LilyPond, as used by xml2ly and Grame's \
> experimental web site at https://libmusicxml.grame.fr, is available through these \
> functions: 
> /*!
> \brief Converts a MusicXML representation to the LilyPond format.
> \param file a file name
> \param out the output stream
> \return an error code (\c musicFormatsError::k_NoError when success)
> */
> EXP musicFormatsError musicxmlfile2lilypond (
> const char *file, const optionsVector& options, std::ostream& out, std::ostream& \
> err); 
> /*!
> \brief Converts a MusicXML representation to the LilyPond format.
> \param fd a file descriptor
> \param out the output stream
> \return an error code (\c musicFormatsError::k_NoError when success)
> */
> EXP musicFormatsError musicxmlfd2lilypond (
> FILE* fd, const optionsVector& options, std::ostream& out, std::ostream& err);
> 
> /*!
> \brief Converts a MusicXML representation to the LilyPond format.
> \param buffer a string containing MusicXML code
> \param out the output stream
> \return an error code (\c musicFormatsError::k_NoError when success)
> */
> EXP musicFormatsError musicxmlstring2lilypond (
> const char *buffer, const optionsVector& options, std::ostream& out, std::ostream& \
> err); 
> 
> I'm no Python nor Scheme developper, but I guess this can be used with suitable \
> interfaces from applications written in these languages. 
> I'll be happy to collaborate to using musicformats to export from within LilyPond \
> if such an attempt is done.

Well, I'm afraid I can't help coding, C++ is not my world. Though, I'd
really love to see LilyPond being able to do:
lilypond --musicxml file.ly
resulting in a correct file.xml.

Best,
  Harm


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