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. Fortunately there are several 3rd party libraries that do provide support for reading in videos and webcams!

Reading Videos

This section describes different approaches that can be used to read in video files.

Loading Image Files

The most straight forward way to read video is to convert it into an image sequence. How you do that is dependent on what OS your using and is left as an exercise for the reader. Typically the way images are handled on the desktop is to first read them in as a BufferedImage and then convert that image into a BoofCV image format. Here's an example for where a sequence of images is loaded from a directory.

List<BufferedImage> images = UtilImageIO.loadImages("path/to/images","jpg");
GrayU8 gray = new GrayU8(1,1);
for( BufferedImage image : images ) {
    ConvertBufferedImage.convertFrom(image,gray,true);
}

Individual images are also loaded easily using UtilImageIO.

Reading MJPEG

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.

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.

Other Video Formats

The easiest way to use Video in BoofCV is to use the default MediaManager. 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. Make sure you add the BoofCV module JavaCV to your project! JavaCV provides a wrapper around FFMPEG. If you don't include this package you will be stuck with just MJPEG files.

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. Note that a built in MediaManager is not provided for these options.

• 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. You need to be sure that the BoofCV WebcamCapture module is included with your project.

Webcam Capture Example

Other Options:

• Video for Linux for Java (V4L4J) used to be supported and can still be used but you will need to write your own code to extract the images.

BufferedImage

As previously mentioned BufferedImages can be converted into a BoofCV image. Thus any library which can read a file into BufferedImages can be used with BoofCV.

Android

See Android Support for how to convert Android images into a BoofCV image.