java - 使用 JAVA 代码从视频文件 (.mp4) 创建视频预览图像，如 YouTube 或 Whatsapp

Question

问题 1. 当我使用 FFmpeg Java api 时，程序在grabber.start()之后不运行并打印任何内容。未生成预览​​。

代码示例:

public static boolean generatePreviewImage(String filePath, String previewFileName ) throws IOException {
        boolean isPreviewGenerated = false;
        System.out.println("Request received to generate thumbnail for video.");
        System.out.println("VideoFilePath : "+filePath);
        System.out.println("ResultFileName : "+previewFileName);
        try {

            FFmpegFrameGrabber fGrabber = new FFmpegFrameGrabber(filePath);
            System.out.println("FrameGrabber found "+fGrabber);
            fGrabber.start();
            System.out.println("Frame started..");
            ImageIO.write(fGrabber.grab().getBufferedImage(), "jpg", new File(previewFileName));
            System.out.println("Image written successfully as "+previewFileName);
            isPreviewGenerated = true;
            fGrabber.stop();
            System.out.println("FrameGrabber stopped.. "+fGrabber);

        } catch(Exception e){
            System.out.println("Exception while creating video thumbnail : "+previewFileName+" - exception - "+e);
            e.printStackTrace();
        }
        System.out.println("Image written successfully? "+previewFileName);
        return isPreviewGenerated;
    }   

结果:收到生成视频缩略图的请求。视频文件路径:/root/appdir/VIDEO20171124143855.mp4结果文件名:/root/appdir/vdthumb_0.jpgFrameGrabber 发现 org.bytedeco.javacv.FFmpegFrameGrabber@3529360e

在上述语句之后没有任何反应并被打印..

<小时/>

附加信息:我也在 Linux VPS 上安装了 FFmpeg，并且能够使用命令行生成预览root@vps19984[~/usr/appdir]#ffmpeg -i/root/appdir/.VIDEO20171123165555.mp4 -r 1 -f image2 image-%2d.png(上面的命令 ffmpeg 在 Linux 机器上成功生成预览，但我想通过 Java 程序生成它)

<小时/>

问题 2。当我使用 JCodec api 时，程序生成黑色图像，但不是视频文件中的图像。代码示例:

public static boolean generatePreviewImage(String filePath, String previewFileName ) throws IOException, JCodecException {
    logger.info("Request received to generate thumbnail for video. VideoFilePath : "+filePath+", resultFileName "+previewFileName);
    boolean isPreviewGenerated = false;
    Picture framePic = FrameGrab.getNativeFrame(new File(filePath),20);
    logger.info("Frame grabbed successfully..");
    Transform transform = ColorUtil.getTransform(framePic.getColor(), ColorSpace.RGB);
    Picture rgb = Picture.create(framePic.getWidth(), framePic.getHeight(), ColorSpace.RGB);
    transform.transform(framePic, rgb);
    logger.info("Frame transformed successfully to RGB..");
    BufferedImage dst = new BufferedImage(rgb.getCroppedWidth(), rgb.getCroppedHeight(),
            BufferedImage.TYPE_INT_RGB);
    ImageIO.write(dst, "jpg", new File(previewFileName));
    isPreviewGenerated = true;
    logger.info("Is preview generated.."+isPreviewGenerated);

}

结果: 收到生成视频缩略图的请求。视频文件路径:/usr/appdir/VIDEO20171123165555.mp4，结果文件名/usr/appdir/vdthumb_0.jpg 抓取成功.. 帧成功转换为 RGB.. 是否生成预览..true

问题:JCodec 生成 5 KB 的黑色 jpg 图像

Answer 1

检查此代码，因为它成功创建了文件。做了一些更改。这是问题1的解决方案。如果您无法查看日志，则问题出在记录器上。您可以粘贴您正在使用的记录器或通过 Google 搜索您的记录器的问题。

public static boolean generatePreviewImage(String filePath,
        String previewFileName) throws IOException, Exception {
    logger.info("Request received to generate thumbnail for video. VideoFilePath : "
            + filePath + ", resultFileName " + previewFileName);
    boolean isPreviewGenerated = false;
    FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(filePath);
    logger.info("FrameGrabber found " + grabber);
    grabber.start();
    logger.info("FrameGrabber started.. " + grabber);
    for (int i = 20; i < 22; i++) {
        logger.info("Reading first 2 images..");
        ImageIO.write(grabber.grab().getBufferedImage(), "jpg", new File(
                previewFileName + "_" + i));
        logger.info(i + " image written successfully as " + previewFileName
                + "_" + i + ".jpg");
        isPreviewGenerated = true;
    }
    grabber.stop();
    logger.info("Is preview generated.." + isPreviewGenerated);
    return isPreviewGenerated;

}