Syllabus 20091013

Flexible Loops: Variables

Some examples of other forms of "cultural loops", the role for instance of repetition in the lyrics of songs. Examples of work songs, like the waulking songs of Scotland, and the cumulative song form, popular for teaching children language, or for cross-cultural purposes. We will look at some excerpts from Lomax: the songhunter. Example exercise: song construction: Recreate the lyrics of a simple song with (nested) loops.

Assembling a movie from images / sound

ffmpeg -y -r 3 -b 1800 -sameq -i frames/%06d.png foo.mp4

http://electron.mit.edu/~gsteele/ffmpeg/

Lab

"Command-line after effects": Using command-line media tools to "filter" a movie

Extracting frames from a movie

Example 1 : Blurring every frame

ffmpeg -i ~/Videos/LomaxTheSongHunter.avi -an -y -ss 0:07:30 -t 00:00:01 -f image2 frame%04d.png

Now we use mogrify to apply a blur (the *same* blur) to *every frame*.

mogrify -blur 5x5 *.png

ffmpeg -y -r 25 -b 1800 -sameq -i frame%04d.png test.mpeg

or to make an OGG-Theora format video:

ffmpeg -y -r 25 -b 1800 -sameq -i frame%04d.png test.ogv

for i in range(25):
    print "mogrify -blur " + str(i) + "x" + str(i),
    print "frame%04d.png" % (i+1)

Assignment

To be completed after the break: Create a "command-line movie" using ImageMagick, sox, and ffmpeg.

Reading: Chapter 1 of ThinkPython.

Resources

• http://automatist.net/techdaze/MediaBashing (to be moved into the CookBook)