Converting Files under Linux

Convert Images

Use the powerful command convert
```
convert file.jpg file.gif
convert file.tiff file.jpg
```
The command convert can convert between several formats and has a lot of options, see man convert

Resizing an image

convert -resize 50%       file.jpg file_small.jpg
convert -resize 200x200   file.jpg file_small.jpg      # ratio will be kept
convert -resize 1024x768! file.jpg file_desktop.jpg    # ! = force the new size

Rotating an image

convert -rotate 90 file.jpg file_new.jpg

Convert between Windows/Mac and Linux text files

Use dos2unix and unix2dos

dos2unix win.txt linux.txt
mac2unix mac.txt linux.txt
unix2dos linux.txt win_mac.txt

Convert text files between different character encodings

Use iconv to convert a text file

iconv --from-code=UTF-8 --to-code=ISO-8859-1 text_in_utf-8.txt > text_in_iso-8859-1.txt

Convert PS and EPS Files

There is normally more than one way to convert files. Just try out which tool produces the best results in your case.

Convert PS to PDF

ps2pdf file.ps
ps2pdf -sPAPERSIZE=a4 -dOptimize=true -dEmbedAllFonts=true file.ps
pstoedit file.ps file.pdf

Convert EPS to PDF

epstopdf file.eps
pstoedit file.eps file.pdf

Convert PS to EPS
```
ps2eps file.ps
```

Convert to a "better" PS

ps2ps   file.ps  new.ps    
eps2eps file.eps new.eps   
ps2ps2  file.[ps|eps|pdf] new.ps    # converts to PS level 2

Extract text from PS
```
ps2ascii file.ps file.txt
```

Convert a postscript file to png

gs -r300 -dNOPAUSE -dUseCropBox -dBATCH -sDEVICE=pngalpha -sOutputFile=file.png file.ps    # r300 = resolution of 300 dpi

Convert a postscript file to jpg

gs -r300 -dNOPAUSE -dUseCropBox -dBATCH -sDEVICE=jpeg -sOutputFile=file.jpg file.ps    # r300 = resolution of 300 dpi

Convert a transparent eps (in cmyk) to a png file
```
convert -colorspace rgb file.eps file.png
```

Convert GRIB into NETCDF files

Use NCL to convert. First load ncl module
```
module load ncl
```

Rename your GRIB file. The name should have .grb as extension
```
mv mygribfile mygribfile.grb
```

Convert to NETCDF
```
ncl_convert2nc mygribfile.grb
```
The resulting NETCDF file will be mygribfile.nc

For more information see http://www.ncl.ucar.edu/Document/Tools/ncl_convert2nc.shtml

Convert PDF Files

Use pdftops to convert PDF to PS
```
pdftops file.pdf
```
Note: pdf2ps does also convert PDF to PS, but normally the result is worse.

Extract text from PDF

pdftotext file.pdf
# or use ps2ascii
pdftops file.pdf
ps2ascii file.ps file.txt

Convert a PDF file to images (one image per page)
```
pdftoppm file.pdf image
```
Convert page 2 (-f 2) to page 5 (-l 5) with a resoltion of 300 dpi (-r 300) to five PPM image files
```
pdftoppm -f 2 -l 5 -r 300 file.pdf image
```

Extract images from PDF files

pdfimages file.pdf image
pdfimages -j file.pdf image    # write images if possible as JPEG files

Open the PDF File with an application and save it in a different format. Programs that can open PDF files:
```
abiword
oowriter
```

Manipulating PDF Files

Use pdfedit to edit PDF Files
```
pdfedit file.pdf
```

Joining PDF files

pdfunite file1.pdf file2.pdf file-new.pdf
pdfjoin file1.pdf file2.pdf                # alternative

Splitting a PDF file into pages
```
qpdf --split-pages file.pdf %d-out.pdf
```

Extract certain pages from a PDF. For example page 22-36

qpdf input.pdf --pages . 1-10 -- output.pdf
pdftops input.pdf - | psselect -p22-36 | ps2pdf - output_p22-p36.pdf

Extract images from PDF files
```
pdfimages -j file.pdf image
```

Rotating PDF file
```
pdf90 file.pdf
```

Put several pages on one page:

pdfnup --nup 2x1 file.pdf     # 2 pages side by side
pdfnup --nup 2x2 file.pdf     # 4 pages on one page

Convert Matlab EPS Files

Convert Matlab eps file in a pixel graphic like png, jpg: First convert the eps file into a pdf file. Afterwards convert the pdf file into a png or jpg file
```
epstopdf matlab_plot.eps 
convert -density 100 matlab_plot.pdf matlab_plot.png
```
- Choose a higher number than 100 to get a higher resolution of the image
- Instead of png you can convert to matlab_plot.jpg

Convert Matlab eps file into a .emf file (Enhanced Meta File format). emf is still a vector based format and can be imported by openoffice.
```
pstoedit -pta matlab_plot.eps matlab_plot.emf
```
The crucial option is -pta, which fixes the ugly looking font when you directly import the eps file into openofffice (-pta sets correct inter-letter spacing).
With the above command the boundary box will be still broken (too large). If you first convert it into a pdf file it will be ok.
```
epstopdf matlab_plot.eps
pstoedit -pta matlab_plot.pdf matlab_plot.emf
```

Convert tar files into zip files

Windows users may not be able to open tar or tar.gz files. The following commands "convert" these files to zip files
```
tar xfv  file.tar    | zip file.zip "-@"
tar xfvz file.tar.gz | zip file.zip "-@"
```

Convert MS Excel and MS Word files

Convert xls (Excel) files to csv (comma-separated values) files:
```
xls2csv -x file.xls -c file.cvs -a UTF-8
```

Convert MS Word to plain text:
```
abiword --to=txt file.doc
```

Alternatively open the file with LibreOffice.

Create a Movie out of Images

Programs

mencoder: Encoding from multiple input image files: http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-enc-images.html:
convert: create animated GIFs

Create animated gif with convert

Animated gif file created from a series of png or gif files ( see also man convert):

convert -delay 30 -loop 0 *.png animated.gif
convert -delay 30 -loop 0 *.gif animated.gif

mencoder takes jpg or png files as imput. Note: mencoder needs png with 8bit color depth, use option -depth 8

Convert eps to png files

mogrify -format png -depth 8 -alpha off -density 600 -resample 150 *.eps

Convert jpg tp png files and keep the quality

mogrify -format png -depth 8 -quality 100 *.jpg

Create movies with mencoder (see also man mencoder)

Create AVI movie file with MPEG4 codec (fps = frames per second):

mencoder mf://*.jpg -mf fps=5 -ovc lavc -o output_mpeg4.avi
mencoder mf://*.png -mf fps=5 -ovc lavc -o output_mpeg4.avi

Create AVI file with XVID codec

mencoder mf://*.png -mf fps=5 -ovc xvid -xvidencopts fixed_quant=4  -o output_xvid.avi

Create AVI file with X264 codec (use 2 pass mode: pass=1 will analyze the frames, pass=2 will create the movie)

mencoder mf://*.png -mf fps=5 -o /dev/null       -ovc x264 -x264encopts pass=1:turbo:bitrate=1600:bframes=1:me=umh:partitions=all:trellis=1:qp_step=4:qcomp=0.7:direct_pred=auto:keyint=300
mencoder mf://*.png -mf fps=5 -o output_x264.avi -ovc x264 -x264encopts pass=2:turbo:bitrate=1600:bframes=1:me=umh:partitions=all:trellis=1:qp_step=4:qcomp=0.7:direct_pred=auto:keyint=300

X264 and XVID codecs create smaller and qualitative better files than MPEG4 codec, where has X264 creates smaller files than XVID.
Note: For mencoder the file should not be too large. 1000x1000 is still fine

Convert Movie/Animation Files

Convert MPEG4 movie to Quicktime (qtrle) movie

ffmpeg -i output_mpeg4.avi -f mov -vcodec qtrle output.mov

Convert animated GIF into MPEG4 movie. First extract individual pictures out of the animated gif and save them as png files
```
convert animation.gif animation%02d.png
```
Now create out of the png files a MPEG4 movie
```
mencoder mf://*.png -mf fps=5 -ovc lavc -o output_mpeg4.avi
```

Converting Flash movie

ffmpeg -i myvideo.flv -f avi -vcodec mpeg4 myvideo_mpeg4.avi

Convert Audio Files

Convert WAV to MP3. Set the bit rate with option -b
```
lame -b 320 file.wav file.mp3
```

Convert WAV to OGG. Set quality between -1 (very low) and 10 (very high) with option -q:
```
oggenc -q 8 file.wav 
```

Convert audio files using sox

sox file.mp3 file.ogg
sox file.ogg file.mp3

Convert media files using mplayer. Mplayer can convert every file format, which he can play, to .wav
```
mplayer -vo null -vc dummy -af resample=44100 -ao pcm:waveheader:file=output.wav input.xxx
```

Converting a bunch of files using a for loop (works in bash shell only!)

for f in *.wav;  do lame -b 320 "$f" "${f%.wav}.mp3"; done
for f in *.flac; do flac -cd "$f" | lame -b 320 - "${f%.flac}.mp3"; done
for f in *.ogg;  do sox "$f" "${f%.ogg}.mp3"; done
for f in *.ogg;  do oggdec -o - "$f" | lame -b 256 - "${f%.ogg}.mp3"; done
for f in *.wma ; do mplayer -vo null -vc dummy -af resample=44100 -ao pcm:waveheader "$f" && lame -b 256 audiodump.wav -o "${f%.wma}.mp3"; done; rm -f audiodump.wav

Extract Audio from a Video File

Extract MP3 audio from MP4 video

for f in *.mp4; do ffmpeg -i "$f" -vn -ar 44100 -ac 2 -ab 320k -f mp3 "${f%.mp4}.mp3"; done

Extract MP3 audio from MKV video

for f in *.mkv; do ffmpeg -i "$f" -vn -ar 44100 -ac 2 -ab 320k -f mp3 "${f%.mkv}.mp3"; done