MediaBashing
core concepts: bitmap, PCM, frame rate, sampling rate, frame size, data rate, compression, lossless vs. lossy compression, codecs, spatial compression, temporal compression, keyframes, VBR, 2-pass encoding
http://en.wikipedia.org/wiki/Pulse-code_modulation
http://en.wikipedia.org/wiki/Video_compression
Examples
Examples of appending images in bash, including a simply "flow" layout algorithm... BashAppendingImages
Encoding Videos (including flash flv's) to DIVX/AVI with mencoder
Basically to encode any format that mplayer understands to a divx file (which is a version of mpeg4, and typically stored in an "avi" format file), you use something along the lines of:
mencoder -oac mp3lame -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=600 -o newmovie.avi sourcemovie.flv
This specifies the "libavcodec" (lavc) to do the video compression, and options to that (separate) library are given as "lavcopts". To, for instance, specify an output frame frame (ofps) of 15fps *and* to limit the maximum number of frames between keyframes to one second (15 frame thus), you could use:
mencoder -oac mp3lame -ofps 15 -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=600:keyint=15 -o newmovie.avi sourcemovie.flv
Images to movie
with ffmpeg
ffmpeg -y -r 3 -b 1800 -sameq -i frames/%06d.png foo.mp4
source: http://electron.mit.edu/~gsteele/ffmpeg/
with mencoder
mencoder "mf://*.jpg" -o movie.avi -ovc lavc -lavcopts vcodec=mjpeg
source: http://www.gfd.geophys.ethz.ch/~pjt/makingMovies.html also: http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-enc-images.html
Movie to images
with ffmpeg
ffmpeg -i movie.avi -f image2 -y -r .01 -an frame %06d.jpg
ffmpeg -i FILE0007.MOV -f image2 -y -an frame%06d.png
ffmpeg -i source.mov -an -y -t 0:0:0.001 -f image2 poster.png
ffmpeg -i source.mov -an -y -ss 0:01:30 -t 0:0:0.001 -f image2 frame.png
mplayer
mplayer -vo png rearwindow.avi
Important command line tools
video
audio
Other useful (GUI) apps
Audacity, Kino
Resources
- Linux Video Production: the State of the Art, by Dan Sawyer, http://www.linuxjournal.com/article/8589