7/6/10 Daily Journal of AT

Well, I've got more to show for my efforts today, even if they're all in picture form.

I started today by trying to get the BeatFinder to be more consistent. I ended up abandoning the function that finds the proper multiplier based on surrounding loudness, as it only ended up deleting all useful data. I decided on a base multiplier of 1.1 times the average as the threshold for a beat, as anything more started cutting out actual peaks. I stuck with base beats only today, and analyzed a few different songs. I also wrote a "cleaning" function for the beats. Basically, as it is now, if there is a hit on a base drum (or a really low base guitar note), the function registers it as a beat. It takes samples every portion of a second, so naturally, if one note lasts for a quarter not span, it will return a lot of "beats" in a row, rather than just one. I used four different songs (Sweet Caroline remix, My Sharona, Wild World, and Maple Leaf Rag) that had four different strengths of back beats (strong, moderate, weak, and none, respectively). I ran them with no cleaning, .1 second cleaning, and .2 second cleaning. These are the results:

Sweet Caroline (techno remix)


My Sharona (acordian rock remix)


Wild World (original country)


Maple Leaf Rag (piano only)

Looking at them through Audacity, it becomes much easier to see and compare how each cleaning function is doing. At the top of each image is the sample of the song being played, then the uncleaned beats, the .1 sec cleaned beats, and the .2 second cleaned beats.

With the steady techno beat, no beats are lost in the .2 sec cleaning, and the .1 cleaning leaves them messier than they should be (if we want one beat in the file for each actual beat). However, such a rigourous cleaning causes the rock song to lose notes. With the slower country, it's not as apparent either way, and the acoustic piano shouldn't bet getting very strong peaks (it probably has a few from low notes, resonance, and a bit of spill). In any event, depending on which kind of music is being analyzed (namely, slow or fast, loud or soft) would determine which cleaner would be more useful. As the computer should be (eventually) able to decide this on it's own when running the program, I left the second length as a changable variable.

In other news, the power briefly went out today. Fortunately, I saved recently enough that no work was lost.