Tuesday, March 20, 2012

Extracting Pages from PDF

First, install PDFTK on Linux.

Then, do this command:

pdftk foo.pdf cat 2-3 output abstract.pdf dont_ask

Where foo.pdf is the original PDF file, 2-3 is the range of pages (you can type 2-end to extract to EOF), and abstract.pdf is the output PDF file.

Saturday, March 10, 2012


$ ffmpeg -i input.avi -qscale 1 -qcomp 0 file-%03d.jpg

  • qscale[:stream_specifier] q (output,per-stream)’
    • Use fixed quality scale (VBR). The meaning of q is codec-dependent.
    • qscale constant quality buf variable bitrate. n = 1 for best quality, n = 31 for worst quality
  • qcomp compression
    • video quantizer scale compression (VBR) (default 0.5). Constant of ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0
  • qblur blur
    • video quantizer scale blur (VBR) (range 0.0 - 1.0)
    • Previously tested with qblur option of 0 and 1, and outputs were exactly the same

Friday, March 9, 2012

Converting HD720 to 320x240

$ ffmpeg -i input.avi -vcodec huffyuv -vf "crop:960;720:0:0" -y intermediate.avi
$ ffmpeg -i intermediate.avi -vcodec libx264 -s qvga -y output.m4v

HuffYUV is a lossless codec. From Wikipedia:

Huffyuv (or HuffYUV) is a lossless video codec created by Ben Rudiak-Gould which is meant to replace uncompressed YCbCr as a video capture format.

Despite the "YUV" in the name, it does not compress the YUV color space, but YCbCr.[citation needed] The codec can also compress in the RGB color space.

-vf "..." replaces -croptop, -cropbottom, -padtop, -padbottom etc of older versions of FFMPEG