java截取视频图片做封面

添加org.bytedeco依赖

     org.bytedeco
     javacv
     0.8

    /**
     * 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
     */
    public static void fetchFrame(String videofile, String framefile) throws Exception {
        File targetFile = new File(framefile);
        FFmpegFrameGrabber ff = new FFmpegFrameGrabber(videofile); 
        ff.start();
        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.grabFrame();
            if ((i > 5) && (f.image != null)) {
                break;
            }
            i++;
        }
        IplImage img = f.image;
        int owidth = img.width();
        int oheight = img.height();
        // 对截取的帧进行等比例缩放
        int width = 800;
        int height = (int) (((double) width / owidth) * oheight);
        BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
        bi.getGraphics().drawImage(f.image.getBufferedImage().getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);
        ImageIO.write(bi, FileKit.getFileExtension(framefile), targetFile);
        //ff.flush();
        ff.stop();
    }