Tutorial Videos and Webcams
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 GUI widgets but uses Swing instead. The same philosophy applies to capturing images from videos and webcams. Unfortunately the built in support in Java for reading videos and webcams is very limited.
The only video format which BoofCV natively supports is MJPEG and image sequence. MJPEG is a very simple video format that is for the most part a series of JPEG images concatenated together. MJPEG's inclusion in BoofCV was primarily to provide video support in applets. Support is also provided for reading image sequences from directories.
Third party libraries are required for webcams and reading video formats. Support for these third party libraries can be found in the 'boofcv/integration' directory. Of most interest to people are the wrappers for JavaCV and Webcam Capture. JavaCV provides a wrapper around FFMPEG. Webcam Capture wraps several different webcam libraries into a simple interface, see their website for details.
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.
Video
The easiest way to use Video in BoofCV is to use the default media manager. It checks your class path to see what you have installed and will use the best option available. SimpleImageSequence is an interface that provides an easy to use and common interface for different image streams.
MediaManager media = DefaultMediaManager.INSTANCE;
SimpleImageSequence<Planar<GrayU8>> video = media.openVideo(fileName, ImageType.pl(3,GrayU8.class);
while( video.hasNext() ) {
Planar<GrayU8> input = video.next();
... process ...
}
The following is a list of alternatives:
- Xuggler used supported but after a long protracted death is no longer available
- 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
The recommended way to use webcams with BoofCV is with Webcam Capture. Webcam Capture is very easy to use and works out of the box on Linux, Windows, and MacOS. The BoofCV integration package only provides a single function for opening up a camera at a resolution as close to the one you requested as possible.
Support is also provided for Video for Linux for Java (V4L4J), but it is more difficult to use and is Linux only.
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.
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.
