Overview of work this week

In the last post I talked about tempos and how the support for those were progressing. I have written tests to verify this feature is working as intended, and submitted a pull request for this feature which has now been merged into the Musescore master branch, so that bug is now closed as fixed. The support for voltas, which I mentioned last time I had made a pull request for, has now also been merged so that’s out of the way.

For the bug concerning the incorrect import of copyright text, tests have been created to verify this is done correctly and they are now also in the master branch of the Musescore repository, so the bug has been closed as fixed.

One of the areas I’ve been looking at this last week is support for importing bends. Bends are a common feature in Guitar Pro files, so support for this is important. There are various different kinds of bends that can be created in Guitar Pro (e.g. Bend/Release, Prebend, etc), all of which are now supported in the version I currently have on my local machine, including arbitrarily complicated bends. There is currently an outstanding issue with this work, and that is to do with the test framework. For some reason, the test files I have created are not processed correctly and the test framework fails – as there is nothing fundamentally different about these tests I presume that the reason for the problem is something specifically related to bends. I need to set aside some time to look into this error further, I expect I’ll do that this week. After I have managed to fix this issue with the test framework, I’ll push that to my fork on Github and add a pull request.

The other main task which I have spent time on is supporting the GPX format. GPX files are files which are compressed with a proprietary compression algorithm, and within that is a file system I have already decompressed the compressed GPX file, and extracted the files in the file system and dumped them to disk so that I can get an idea of what I’m working with. Most of the meta information is now handled (title, artist, etc), though there are some tags which aren’t supported yet as I need to figure out the right place to put them. My goal for the moment is to focus on just the notes themselves – details such as voltas and slurs etc. can be completed afterwards. This will allow me to get something that works to some extent, and is stable, into the master branch of the Musescore repository as early as possible. One of the files in the file system is an XML file named “score.gpif”, and contains the vast majority of the important information that needs to be processed. I have extended the implementation this past week to read instrument descriptions and create parts for them. Measure information is also handled, so we know how many measures there are in the score, and characteristics of those measures (such as clef and key signature), which is also extracted from the score.gpif file. There still is much work to do on the GPX format, and that’s what I’ll continue to look at this week.

I’ve also taken a look at the issue where fade-ins are not supported. I need to create an additional symbol in Musescore in order to do this. I think the best way to go about that is to make some kind of variation on hairpin.cpp, which describes how e.g. crecendos are drawn. Perhaps instead I want to use a bezier curve to describe the fade symbol. I intend to find time to get that issue sorted out this week too.

Key tasks that stalled

The bends feature is taking a little longer than I would like, that’s down to the problems in running the bends tests described earlier. I expect to work on that more this week so that this can get out the way.

There are a few issues also with creating measures in GPX files that’s taking longer than expected. Currently, clicking on measures which have been created makes a segmentation fault in Musescore. I’ve played about with this a fair bit, and I’m starting to think that’s because the measures have been created with no notes or rests, as that information hasn’t been parsed yet so I can’t fill the measures with the right information. If that’s the case, this should just clear up this week as I make progress with the implementation of support for GPX files.

Upcoming tasks this week

This week I primarily intend to continue working on the support for the GPX file format. My hope is that I can parse all the notes, rhythm descriptions etc. in the score.gpif files and display them on the score. I’ll look also at the issue with guitar fade-ins described previously, after the symbol is ready to use it shouldn’t be too complicated to finish off importing the Guitar Pro file correctly. The bends issue I also would like to get out of the way, as the support for that has been completed and I should just need to find a way around this problem that’s currently appearing with the test framework. I’d like to spend some time looking at some of the existing other issues too however, just so I know what’s around the corner…

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