[Staging] Neon should check if clef has invalid `@line`

[yinanazhou]

Recent MEI files have clefs that have invalid @line attribute.

Expected behaviour:

• Neon should give notification about it and provide @mei:id
• Neon should have new MEI action that can fix it
• MEI encoding job in Rodan should be fixed regarding this

[yinanazhou]

Hi @JoyfulGen and @annamorphism, I noticed that Rodan produces clefs with invalid line. In MEI, the value must be in the range between 1 and the number of lines on the staff. But I've found straight outta OMR files have clefs with line equals to 0 or 5. I wonder what is the best way to fix this. We have two options for the MEI action:

1. remove the invalid clefs
2. modify the value, so that all values below 1 would be changed to 1, and all values above 4 would be changed to 4

Which one would you prefer?

[JoyfulGen]

@yinanazhou I would love to see some examples of these invalid clefs, just to see if they're in places they should be or not. I've been looking through my files, but I haven't found any so far. Do you have examples?

[yinanazhou]

I noticed one in this file when testing the clef issue. The clef on the 5th staff does not have @line, and verovio is not drawing it.
289 eliza staging(1) (1).mei.zip

[JoyfulGen]

That file is already a bit old! Things have been moving pretty fast. Our most recent files are here: https://github.com/DDMAL/e2e-omr-resources/tree/main/resulting_mei_files/MS73/Ready%20for%20Neon. I'll have another look at those to see if I can find an invalid clef!