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Optical Music Recognition

Some time ago, the What’s the score at the Bodleian? project team went to see Matt McGrattan at The Bodleian Digital Library Systems and Services. We wanted to find out what it would take to be able to use our digitized scores to automatically generate a sound file to go with the sheet music, and Matt had been looking into this.

A number of programs exist that will convert images of music into a kind of notation that can be read by computers to, for example, generate a sound file or be used as input into music editing programs. Background reading on the matter had suggested that it was unlikely that our material would convert easily as far too many variables were non-ideal (some references in the Optical Music Recognition Bibliography). We nevertheless wanted to explore what it would take to make it worth-while to include automatic music recognition in the project.

Screenshot of Audiveris interface (from http://audiveris.kenai.com/)

Screenshot of Audiveris interface (from http://audiveris.kenai.com/)

The program Matt used for our initial test was Audiveris. Audiveris is an open-source Optical Music Recognition (OMR) tool that can ‘interpret’ music notation and convert it to a form of data (Music XML) that can then be used as input into other programs.

Before we could use the program, our sample file had to be pre-processed (for example making sure it was the right format and size). The file was then loaded into Audiveris and processed as illustrated in the Quick example found on the Audiveris website.

The initial output that we got was not perfect, and what this meant was obvious when the file was used to automatically generate a sound file. Matt suggested it sounded ‘like something by Scott Joplin’. For some kinds of music that is the desired effect, but in this case it was not. It is perfectly possible to post-edit the initial output and manually correct some of the problems, but the time and effort necessary for this means we could not fit it in to the current phase of the project. It is, however, something we want to continue to look into.

This test only included one program (Audiveris) and was performed on only one of our samples. It is possible that other programs will suit our material better, or that this process will be better suited for other types of material. As we are hoping to be able to digitize and make available other kinds of scores in the future, we will continue to explore options for automatic optical music recognition. We’ll report on any further findings as and when we have some.

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What’s a duplicate?

March 15, 2011 2 comments

As we are going through the boxes, we are identifying duplicates, the idea being that we do not need two identical copies of the same item. But what is ‘the same’? It may seem obvious at first – if it is the same piece of music it is a duplicate. But what if it is a different edition, where some changes (may) have been done to the music? Well, then it is not an identical copy and thus not a duplicate. But what if the music is the same but the cover differs?

We have taken the view here that if the cover is different, the items are not duplicates, even if the music would sound identical irrespective of what copy you play it from. The reasoning behind this is that these items are not only music scores. The actual physical copies are interesting, and variations there can very well be of interest to someone researching the genre or period.

The differences between two versions of a score can be quite obvious, like the Valentine Galop pictured here.Different covers for Valentine Galop The covers look different – one has an illustration while the other uses different fonts in a decorative way – which may make it less obvious that this is actually the same music. It is the same composer (although called M Relle on one cover and Moritz Relle on the other), but the title is slightly different (St Valentine’s Galop vs Valentine Galop). It is only by looking at the actual music notation that we will know if it is the same piece. In this case it is easy to motivate scanning both copies, since there is so much to look at and compare for someone researching the area.

In other cases, duplicates may be less obvious. It may be that the cover looks very similar, but a closer inspection reveals small differences, for example that the advertisements on the back are different or that the list of titles in the series contains different number of items. If these were to be considered duplicates, which one should be scanned? Who should decide that one set of adverts is more important or interesting than another? We have refrained from making that decision and are instead scanning both copies in cases like these. This will allow different kinds of research on the material. The actual number of near-duplicate scores is fairly low, so seen in the grand scheme of things scanning the near-duplicates it is a small extra. Having them does however also allow a further interesting use, namely for quality assurance. Having the same title described twice will allow us to make comparisons between the different descriptions and see in what way they differ (if at all). That will help us understand how much variation we should expect in the descriptions that we are getting. There are other ways this quality assurance can be performed, and we will be using various methods to get material that is truly useful for those who wish to make use of it.

Galops

While going through the boxes of scores I’ve seen a lot of ‘gallops’ and ‘galops’. Wikipedia says: “the galop, named after the fastest running gait of a horse … is a lively country dance, introduced in the late 1820s to Parisian society by the Duchesse de Berry and popular in Vienna, Berlin and London.”

Cover from one galop piece

One of many galops

Our music is considerably younger than 1820, so it seem the dance remained in vogue. Or perhaps only became popular and played in the home later on?

Some examples of the galop dance can be found online (for example on YouTube). Even if the music is not from our collection (as far as we know yet, anyway), I think these films really help us imagine what it would have been like when people were dancing galops.

Galops were not only dance music or ‘simple’ music but many well-known composers have written galops, including Johann Strauss II, Dmitri Shostakovich and Franz Liszt. Listen to his Grand Galop chromatique played by Valentina Lisitsa (YouTube).

The Devil’s Galop may be familiar to many of us, as it was used in many TV series, including Dad’s Army, The Goodies, the Goon Show, Monty Python and more recently in Mitchell and Webb’s The Surprising Adventures of Sir Digby Chicken-Caesar sketches. This 30 second sample, featuring the The Ukulele Orchestra of Great Britain, may serve as a reminder or introduction.

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