java视频截图

这里介绍的是使用javacv来实现视频截图功能：

maven导包：

    org.bytedeco
    javacv-platform
    1.3.1

工具类：

package indi.chokshen.utils;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

import org.bytedeco.javacpp.opencv_core;
import org.bytedeco.javacpp.opencv_core.IplImage;
import org.bytedeco.javacv.FFmpegFrameGrabber;
import org.bytedeco.javacv.Frame;
import org.bytedeco.javacv.FrameGrabber.Exception;
import org.bytedeco.javacv.Java2DFrameConverter;
import org.bytedeco.javacv.OpenCVFrameConverter;
/**
 * javacv
 * @author chokshen
 *
 */
public  class VideoFrameKit {

    /**
     * 获取指定视频的帧并保存为图片至指定目录
     * @param videofile  源视频文件路径
     * @param framefile  截取帧的图片存放路径
     * @throws Exception
     * @throws IOException
     */
    public static void fetchFrame(String videofile, String framefile)
            throws Exception, IOException {
        FFmpegFrameGrabber ff = new FFmpegFrameGrabber(videofile);
        ff.start();
        String rotate =ff.getVideoMetadata("rotate");//视频的旋转角度
        int lenght = ff.getLengthInFrames();
        int i = 0;
        Frame f = null;
        while (i < lenght) {
            // 过滤前5帧，避免出现全黑的图片，依自己情况而定
            f = ff.grabImage(); //应该使用grabImage而不是grabFrame，这样可以避免mov格式的视频截图失败
            if ((i > 5) && (f.image != null)) {
                break;
            }
            IplImage src = null;
            if(null !=rotate &&rotate.length() > 1) {
                OpenCVFrameConverter.ToIplImage converter =new OpenCVFrameConverter.ToIplImage();
                src =converter.convert(f);
                f =converter.convert(rotate(src, Integer.valueOf(rotate)));
            }
            doExecuteFrame(f, framefile);
            i++;
        }

    }


    public static IplImage rotate(IplImage src,int angle) {
        IplImage img = IplImage.create(src.height(),src.width(),src.depth(),src.nChannels());
        opencv_core.cvTranspose(src,img);
        opencv_core.cvFlip(img,img,angle);
        return img;
    }


    public static void doExecuteFrame(Frame f,String targetFileName) {
        if (null ==f ||null ==f.image) {
            return;
        }
        Java2DFrameConverter converter =new Java2DFrameConverter();
        BufferedImage bi =converter.getBufferedImage(f);
        File output =new File(targetFileName);
        try {
            ImageIO.write(bi,"jpeg",output);
        }catch (IOException e) {
            e.printStackTrace();
        }
    }

}

注意: 应该使用grabImage而不是grabFrame，这样可以避免mov格式的视频截图失败，具体原因见https://github.com/bytedeco/javacv/issues/821