Comment by ivansavz | Hacker News Reader

Comment by ivansavz | Hacker News Reader

For me the biggest game-changer for online video lectures has been this Chrome plugin that allows for fine-grained control of video speed: https://chrome.google.com/webstore/detail/video-speed-contro...

If you have control over the courseware platform used for your course, make sure it uses a compatible video player based on html5 video and not some custom implementation (very rare).

In case video speed controls is not available on your courseware, you can pre-process videos to speed them up to 1.5x using this script (save as `fastervid.sh` and run on video lectures before uploading)

    #!/bin/bash
    if [ -z $1 ]; then
      echo "usage $0 input_video.mp4"
      exit -1
    fi

    echo "Converting $1 to 1.5x speed..."
    ffmpeg -i "$1"  -filter_complex "[0:v]setpts=0.6666666666666*PTS[v];[0:a]atempo=1.5[a]" -map "[v]" -map "[a]" "tmp-$1"

    echo "Delaying audio of $1 by 60ms"
    ffmpeg -i "tmp-$1" -itsoffset 0.06 -i "tmp-$1" -map "0:0" -map "1:1" -acodec copy -vcodec copy  "faster-$1"

    # cleanup temp file
    rm "tmp-$1"

Completely unrelated to the video speedup hacks, but also in the vein of getting a lot of information across faster, one thing you can do for your courses would be to create Concept Maps.

The CmapTools software is very good for this: https://cmap.ihmc.us/cmaptools/

Overall I find concept maps on of the best tools to show an overview of the course (macro maps) or topic (zoomed in maps). As a teacher with extra context about data science you can easily put together something like this for your course that will show learners what there is to learn and allow them to keep track of their progress (e.g. wow when we started all these words were unknown to me, but now I know about 70% of the words on this map already).

I have heard teachers use CmapTools in more active way (asking learners produce concept maps individually or collaboratively), but don't have experience with that myself.

A paper about concept maps: https://cmap.ihmc.us/docs/pdf/TheoryUnderlyingConceptMaps.pd...

And an example of the concept maps I use in my books: https://minireference.com/static/tutorials/conceptmap.pdf

More in this vein, it genuinely floors me that UML-like diagrams (used very loosely and without strictness) aren't more of a thing.

There are so many walls of text out there going over a system's flow that could be expressed in just a couple paragraphs and a companion sequence diagram.

I've found that plug-in to work even where sites try to prevent speed control and skipping, for example our various campus mandatory online training courses.

This is also very satisfying:

document.querySelector('video').playbackRate = 100;

but the videos are often served from a different host and I forgot to record the setting that makes it work in that case.

I also enjoy sped up videos, especially for lectures, but if you preprocess videos to speed them up, make sure to also include the original videos. Students that don't speak your language natively, for example, may be handicapped by fast videos.

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