Out of the box emergence will accept uploads for various image, video, and audio formats. Additional tools need to be installed on the host system though to enable features like video thumbnailing, face-detection cropping, and thumbnailing for advanced image formats.
avconv command is used to extract thumbnails from videos, you can install it on Ubuntu with:
sudo apt-get install libav-tools
Transcoding videos requires the
avconv command as described above and additionally needs
exiftool for extracting rotation metadata which can be installed on Ubuntu with:
sudo apt-get install libimage-exiftool-perl
Vector image thumbnails
To support generating thumbnails for vector formats like PDF, AI, SVG, and PostScript, the
convert command from ImageMagick must be installed. On Ubuntu you can install it with:
sudo apt-get install imagemagick
As of this writing ImageMagick is installed by emergence's quickinstall script and setup guide.
Face detection for cropping
When requesting cropped thumbnails, emergence will by default use a pure PHP library to detect the "noisiest" part of the image to center the crop on. This often works pretty well, but if the
facedetect PHP extension is available emergence will prioritize using it to detect and center on a face in the image. Facial detection requires OpenCV and several other dependencies be in place on the host system.
Instructions on setting up the extension and its dependencies can be found on the project's homepage: http://www.xarg.org/project/php-facedetect/