Tutorial Videos and Webcams
Videos and Webcams in BoofCV
BoofCV focuses on image processing and computer vision algorithms and for the most part relies on other libraries for input and output. For example, BoofCV does not define image widgets but uses Swing instead. The same philosophy applies to capturing images from videos and webcams. Unfortunately the built in support that Java provides for reading videos and webcams is very limited.
The limited built in support that BoofCV provides itself for reading videos directly comes in the form of MJPEG videos and image sequence. MJPEG is a very simple video format that encapsulates a sequence of video images. MJPEG is not the most efficient format, but it is very easy to read and write. Its inclusion into BoofCV is primarily to provide video support to applets. An image sequence contained in a directly can also be read as if it was a video.
Third party libraries are required for reading webcams or other video formats. Support for these third party libraries can be found in the 'boofcv/integration' directory. Currently wrappers are only provided for Xuggler. Libraries which are not 'supported' can still be used easily with BoofCV, you just need to provide the routines to convert the images.
Converting to MJPEG
To read a video and not mess with third party libraries the easiest way to do so is convert the video to MJPEG. The easiest way in Linux to create an MJPEG from some other video format is using ffmpeg. Below is a command line example.
ffmpeg -i FILENAME -sameq example.mjpeg
Other flags can be added to resize the image or adjust image quality. There are a few videos where ffmpeg will produce an MJPEG which BoofCV cannot read, but this is not common.
Xuggler Integration
Xuggler support is still being worked on to make the API easier to deal with. To read a video file as a SimpleImageSequence use XugglerSimplified. For example:
SimpleImageSequence<ImageFloat32> videoLeft =
new XugglerSimplified<ImageFloat32>("FileName.avi", ImageFloat32.class);
Be sure to correctly setup all the classpaths for Xugger and to include the BoofCVXuggler.jar in your classpath. BoofCVXuggler.jar can be downloaded online or compiled yourself using ant scripts provided in 'boofcv/integration/xuggler'.
See also integration JavaDoc
Other Options
The easiest way to integrate a 3rd party library with BoofCV is to read in a frame as a BufferedImage then convert it into a native BoofCV image format using ConvertBufferedImage. An alternative is to write a wrapper that implements SimpleImageSequence, which is used by several examples.
Video Libraries
- Java Media Framework (JMF)
- http://www.oracle.com/technetwork/java/javase/tech/index-jsp-140239.html
- Provided by Oracle and supports a few formats. Known for being old and poorly supported.
Webcams
- Video for Linux for Java (V4L4J)
- http://code.google.com/p/v4l4j/
- I have had good success with it in the past
If you know of some other options please post a message to BoofCV's message board (see sidebar link) letting us know about it! Especially if you have suggestions for Windows and MacOS.
