David A Roberts

Converting videos to 3GP in Ubuntu Intrepid 8.10 with FFmpeg

The default installation of FFmpeg in Ubuntu Intrepid 8.10 doesn't support conversion to 3GP. According to this, installing ubuntu-restricted-extras should fix this, but that didn't work in my case. So, you may need to manually install the required packages:

sudo aptitude install \
libavcodec-unstripped-51 \
libavdevice-unstripped-52 \
libavformat-unstripped-52 \
libavutil-unstripped-49 \
libpostproc-unstripped-51 \
libswscale-unstripped-0

Then, to convert a video, you can either go the command-line route:

ffmpeg -i input.mpg \
-vcodec h263 -s qcif -r 15 -b 100k \
-acodec libfaac -ac 1 -ar 32000 -ab 64k \
output.3gp

Which will convert to input.mpg to output.3gp with:

• H.263 video codec
• QCIF video resolution (176x144)
• 15fps
• 100 kb/s video bitrate
• AAC audio codec (through libfaac)
• 1 audio channel
• 32000 Hz audio sampling frequency
• 64 kb/s audio bitrate

Alternatively, if you prefer using a GUI, you can try Mobile Media Converter (direct link to v.1.4.1 .deb), which seems to work pretty well, and also supports downloading videos directly from YouTube.

Command-line scanning

First you need to find the ID of the required device:

scanimage -L

Output:

device `v4l:/dev/video0' is a Noname Acer CrystalEye webcam virtual device
device `net:linux-box.local:hpaio:/usb/Photosmart_C4100_series?serial=XXXXXXXXXXXXXX' is a Hewlett-Packard Photosmart_C4100_series all-in-one

In this case the device ID is net:linux-box.local:hpaio:/usb/Photosmart_C4100_series?serial=XXXXXXXXXXXXXX Then, for colour scanning:

scanimage -d "net:linux-box.local:hpaio:/usb/Photosmart_C4100_series?serial=XXXXXXXXXXXXXX" \
--mode Color --resolution 300dpi | pnmtopng - > image.png

Or for greyscale scanning:

scanimage -d "net:linux-box.local:hpaio:/usb/Photosmart_C4100_series?serial=XXXXXXXXXXXXXX" \
--mode Gray --resolution 300dpi | pnmtopng - > image.png

Spellchecking LaTeX documents

To spellcheck a LaTeX document, run the following command (replacing 'file.tex' with the name of your document):

aspell -a -t < 'file.tex' | grep "&" | sort -u