Background

Metadata for MP3 files generally takes the form of information about a track's artist, album, etc. The standard format for MP3 metadata is the ID3 tag, which is compatible with most music players. For this assignment, a particular tag of interest is the beats-per-minute (BPM), which measures the tempo of a song. The higher the BPM, the faster the pace of the song.

Part 1

While writing programs, you will often require capabilities beyond the standard libraries (the os and sys modules are standard). In such cases, it is possible to create a library, but generally some research will save you from re-inventing the wheel. For this assignment, reading the ID3 tag from an MP3 file is a key feature. Fortunately, the mutagen module is able to handle this task.

How to install:

Part 2

Write a function that retrieves the artist, track name, track length, and BPM from an MP3 file. It should take a filename as an argument, and return a dictionary. The keys in this dictionary should be "artist", "name", "length", and "BPM" (with values set accordingly.) If BPM information is not in the MP3 metadata, then that dictionary entry should not be used.

For full credit, the definition of this function must be get_MP3_info(filename) and it must return a dictionary.

Part 3

Write a function that recursively traverses a directory and calls get_MP3_info() on each MP3 file that it finds. It should take a directory path as an argument, and return a list. Each item in the list should be a dictionary containing MP3 metadata (obtained from get_MP3_info()).

For full credit, the definition of this function must be process_MP3_library(directory) and it must return a list.

Part 4

Write a function that prints the information gathered in Parts 2 and 3. The tracks should be sorted by descending BPM (highest to lowest). If BPM information is not present, you can skip printing that file's information. For example, a line of output might look like this:

R.E.M. Drive 4:31 140.05

For full credit, the definition of this function must be print_sorted_info(list) and it should not return a value.

Part 5

This program should be executed via the command line, e.g. python mix.py music. The last token (in this case, music) should be the name of a directory, which will be passed as an argument to process_MP3_library(). You can access arguments from the command line by using the argv variable (which is a list) in the sys module.