[vlc-devel] Project: Video Barcodes for VLC

Sebastian Morr sebastian at morr.cc
Wed Feb 6 16:03:12 CET 2013

Hi, developers of my favourite media player!

Have you seen video barcodes? http://moviebarcode.tumblr.com/
I'd like to build a navigation method for VLC that uses those barcodes
as a seek slider. The first prototype is promising:


Currently, it displays an externally-generated image (see shell script
below). Next step is to generate it inside VLC - I stumbled around in
the source for a few days now, but I got lost. I kindly ask for a few

- Where to put the functionality of barcode-generation? Where does it
  belong, logically? Is it a filter module or something else? I'm
  starting with the Qt GUI, as it's the one I use daily, but others
  could follow.

- Can you recommend an (image-holding) data structure that allows easy
  conversion to the different GUIs?

- I need to access the currently open video at arbitrary positions (I'm
  thinking of building the barcode non-sequentially like an interlaced
  GIF). Which modules would I need to do this and how are they related?
  Is there any documentation on the data flow through VLC?

Please Cc me in responses, as I'm not subscribed to the mailing list. Yet.


Here's the script I'm currently using to generate the barcodes (does the
list allow attachments?) - it requires ffmpeg and graphicsmagick and is
codenamed "foocode" ;)



    OUTFILE=$(basename "$INFILE").png

    rm -rf "$TMPDIR"
    mkdir -p "$TMPDIR"

    SECONDS=$(ffprobe -show_format "$INFILE" 2>&1 | grep duration | cut -f2 -d= | cut -f1 -d.)
    SECONDS_PER_FRAME=$(echo "$SECONDS/$WIDTH" | bc -l)

    ffmpeg -threads auto -i "$INFILE" -an -vf "fps=fps=1/$SECONDS_PER_FRAME, scale=20:ih" "$TMPDIR"/frame%8d.jpg
    gm mogrify -resize "1x$HEIGHT!" "$TMPDIR"/*
    gm convert "$TMPDIR"/* +append "$OUTFILE"
    gm mogrify -resize "$WIDTH!x$HEIGHT!" "$OUTFILE"

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