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  1. Storing and graphing time-based data

    In this article we will look into the best way to store time-based data and use it with gnuplot.

    Timezone

    The first thing to realize is that we should specify a timezone when specifying dates and times (“datetimes”). To prevent calculations, I tend to use datetimes in UTC.

    Format

    Next …

  2. Video manipulation with ffmpeg

    Serveral useful recipes for manipulation video with ffmpeg.

    Note that a name within angle brancket (like <this>) represents a generic input or output file.

    Extracting raw audio

    The following recipe extracts the audio from a video file and converts it to WAV format.

    ffmpeg -y -hide_banner -i <input> -vn -c …
  3. Install ntpsec on FreeBSD

    A short article on how to install ntpsec on FreeBSD. Tested with 0.9.7 and 1.0.0.

    Downloading

    You can find several download methods on the ntpsec website.

    Installation

    As of 2017-07-29, the is no port for ntpsec yet. So on FreeBSD you have to compile it yourself …

  4. Using sqlite3 for time management

    After some initial experiments with sqlite as a replacement for a json data file format (which I did not pursue in the end), I have now started using sqlite in earnest. And I must say that I quite like it.

    At $work, we still have to submit written time sheets …

  5. Convert RCS history to git

    Before the rise of git, I used rcs as my version control system. Because I want to standardize on git, I am slowly converting old repositories.

    In this article I’ll be converting my old perl scripts in ~/src/perl.

    Create a fast-import stream

    From the existing repo, we create …

  6. Doing calculations with Python

    As an engineer I do a lot of calculations. These can be done with pen and paper and a calculator, in an IPython notebook or in a throwaway spreadsheet. All of these methods have shortcomings, though.

    Pen and paper is hard to share and (in my case) hard for others …


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