Python tools for working with Sound Pressure Level files generated by the iOS apps SPLnFFT and SPLnWatch with a required in-app purchase which enables the sending of files to Dropbox.
The tools in this repo deal with files that generated by the iOS apps SPLnFFT and SPLnWatch but these tools are neither created nor supported by the author of those apps, Fabien Lefebvre. Instead, these tools were created for Pythonista for iOS based on the following conversation thread.
The binary data files generated by SPLnFFT and SPLnWatch contain Fast Lp and Slow Lp readings (each reading in a 4 byte float32) that are captured 8 times a second, 60 seconds a minute, 60 minutes an hour, 24 hours a day. A day is 86,400 seconds long (60 * 60 * 24) so all files should be:
- 691,200 samples long -- 8 samples per second * 86,400 seconds in a 24 hour day
- 5,529,600 bytes long -- 4 bytes per reading * 2 reading (fast, slow) per sample * 691,200 samples in a 24 hour day
The files will be padded with (0.0, 0.0) samples for all times when the app is not recording Sound Pressure Levels so that all files are the same length regardless of how long the app was actively recording.
- SPLnFFT_Reader_numpy is the primary tool which reads a SPLnFFT.bin file and generates a matplotlib plot.
- SPLnFFT_split reads in a SPLnFFT.bin file and creates a new, smaller file by removing any hours which only contain (0, 0) values from the start and end of the file.
- SPLnFFT_hourly_split creates 24 files each containing one hour of data to allow for more high resolution plots.
- Use SPLnFFT and/or SPLnWatch to record sound pressure levels
- Use the required in-app purchase to save a binary file(s) to Dropbox
- Use Dropbox_file_picker.py to download the binary file(s) into Pythonista
- Run SPLnFFT_split.py to create a smaller file with leading and/or trailing hours of silence removed
- Run SPLnFFT_Reader_numpy.py to graph the results
Please help us to improve these tools by opening an issue or submitting a pull request.
