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Created page with "= 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 [h..."

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= 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 [http://en.wikipedia.org/wiki/Waulking_song waulking songs] of Scotland, and the [http://en.wikipedia.org/wiki/Cumulative_song cumulative song] form, popular for teaching children language, or for [http://www.youtube.com/watch?v=DhWkRvCuzmE cross-cultural] purposes. We will look at some excerpts from [http://www.lomaxthesonghunter.com/ Lomax: the songhunter]. Example exercise: song construction: Recreate the lyrics of a simple song with (nested) loops.

== Assembling a movie from images / sound ==

<source lang="text">
ffmpeg -y -r 3 -b 1800 -sameq -i frames/%06d.png foo.mp4
</source>

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

<source lang="text">
ffmpeg -i ~/Videos/LomaxTheSongHunter.avi -an -y -ss 0:07:30 -t 00:00:01 -f image2 frame%04d.png
</source>

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

<source lang="text">
mogrify -blur 5x5 *.png
</source>

<source lang="text">
ffmpeg -y -r 25 -b 1800 -sameq -i frame%04d.png test.mpeg
</source>

or to make an OGG-Theora format video:
<source lang="text">
ffmpeg -y -r 25 -b 1800 -sameq -i frame%04d.png test.ogv
</source>

<source lang="text">
for i in range(25):
print "mogrify -blur " + str(i) + "x" + str(i),
print "frame%04d.png" % (i+1)
</source>

== Assignment ==

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

Reading: [http://www.greenteapress.com/thinkpython/html/book002.html Chapter 1] of ThinkPython.

== Resources ==
* http://automatist.net/techdaze/MediaBashing (to be moved into the [[CookBook]])

Syllabus 20091013 - Revision history

Migratebot: Created page with "= 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 [h..."