javacv之于视频/GIF解帧及从新拼接生成GIF实现

　　预备接手表情包处理业务,前期处理并不复杂,流程包括 : GIF动图与视频的解帧 , 逐帧处理, 组合各帧获得新的GIF. 通过调研, 整合了ffmpeg的Java CV 可完美处理解帧 , animated-gif-lib 组件包含gif生成的成熟方案 , 进而问题解决.

　　animated-gif-lib + Java CV

　　animated-gif-lib.jar是用来拆分和合成GIF的工具包,主要用到其中的GifDecoder/AnimatedGifEncoder.

　　Java CV 经常使用于音频/图片等处理,其中整合了经常使用的c++类库,例如音频处理的ffmpeg,且可与Open CV配合使用.这里主要用到FFmpegFrameGrabber来取帧/Java2DFrameConverter来类型转换.

　　其实,GifDecoder也能够完成对GIF的解帧,但没法对视频进行操做,且实际使用中发现各帧颜色处理上有误差,但并不影响最后新GIF的合成.综上,为了代码的复用性,采用Java CV来解帧,只使用其中AnimatedGifEncoder来完成合成GIF的操做.

　　代码实现

　　解帧,FFmpegFrameGrabber获取GIF总帧数时异常(),故而采用GifDecoder获取

        String gifPath = "/home/lab/test/11.gif";
        String dirPath = "/home/lab/test/gif/";
        // 用以解帧
        FFmpegFrameGrabber grabberGif = new FFmpegFrameGrabber(gifPath);
        grabberGif.start();
        Frame frame ;
        // 用以获取GIF总帧数
        GifDecoder decoder = new GifDecoder();
        int status = decoder.read(gifPath);
        if (status != GifDecoder.STATUS_OK) {
            throw new IOException("read image " + gifPath + " error!");
        }
        // 类型转换,Frame -> BufferedImage
        Java2DFrameConverter converter = new Java2DFrameConverter();
        int frameCount = decoder.getFrameCount();
        for (int i = 0 ; i < frameCount ; i++) {
            String fileName = dirPath + "img_" + i + ".jpg";
            File outPut = new File(fileName);
            frame = grabberGif.grabImage();
            if (frame != null) {
                ImageIO.write(converter.getBufferedImage(frame),"jpg",outPut);
            }
        }
        grabberGif.stop();

　　合成GIF

        int frameRate = 20;// 新GIF总帧数
        String resGif = "/home/lab/test/22.gif";
        FileOutputStream targetFile = new FileOutputStream(resGif); // 目标文件流
        int margin = 2; // 间隔帧数
        AnimatedGifEncoder en = new AnimatedGifEncoder();
        en.setFrameRate(frameRate);
        en.start(targetFile);
        for (int i = 0; i < frameRate; i++) {
            en.addFrame(converter.convert(grabberGif.grabImage()));
            grabberGif.setFrameNumber(grabberGif.getFrameNumber() + margin);
        }
        en.finish();
        grabberGif.stop();
        targetFile.close();

　　原GIF倒序获得新GIF

        String gifPath = "/home/lab/test/11.gif";
        // 用以解帧
        FFmpegFrameGrabber grabberGif = new FFmpegFrameGrabber(gifPath);
        grabberGif.start();
        // 用以获取GIF总帧数
        GifDecoder decoder = new GifDecoder();
        int status = decoder.read(gifPath);
        if (status != GifDecoder.STATUS_OK) {
            throw new IOException("read image " + gifPath + " error!");
        }
        // 类型转换,Frame -> BufferedImage
        Java2DFrameConverter converter = new Java2DFrameConverter();
        int frameCount = decoder.getFrameCount();
        String resGif = "/home/lab/test/22.gif";
        FileOutputStream targetFile = new FileOutputStream(resGif); // 目标文件流
        AnimatedGifEncoder en = new AnimatedGifEncoder();
        en.setFrameRate(frameCount);
        en.start(targetFile);
        for (int i = frameCount - 1; i >= 0; i--) {
            grabberGif.setFrameNumber(i);
            en.addFrame(converter.convert(grabberGif.grabImage()));
        }
        en.finish();
        grabberGif.stop();
        targetFile.close();

　　基于GifDecoder和AnimatedGifEncoder实现的gif倒序

        String outputPath = "/home/lab/test/001.gif";
        String imagePath = "/home/lab/test/33.gif";
        GifDecoder decoder = new GifDecoder();
        int status = decoder.read(imagePath);
        if (status != GifDecoder.STATUS_OK) {
            throw new IOException("read image " + imagePath + " error!");
        }
        // 拆分一帧一帧的压缩以后合成
        AnimatedGifEncoder encoder = new AnimatedGifEncoder();
        encoder.start(outputPath);
        encoder.setRepeat(decoder.getLoopCount());
        for (int i = decoder.getFrameCount() -1; i >= 0; i--) {
            encoder.setDelay(decoder.getDelay(i));// 设置播放延迟时间
            BufferedImage bufferedImage = decoder.getFrame(i);// 获取每帧BufferedImage流
            int height = bufferedImage.getHeight();
            int width = bufferedImage.getWidth();
            BufferedImage zoomImage = new BufferedImage(width, height, bufferedImage.getType());
            Image image = bufferedImage.getScaledInstance(width, height, Image.SCALE_SMOOTH);
            Graphics gc = zoomImage.getGraphics();
            gc.setColor(Color.WHITE);
            gc.drawImage(image, 0, 0, null);
            encoder.addFrame(zoomImage);
        }
        encoder.finish();
        File outFile = new File(outputPath);
        BufferedImage image = ImageIO.read(outFile);
        ImageIO.write(image, outFile.getName(), outFile);

 　　视频转gif

        String videpPath = "/home/lab/test/t1.mp4";
        String gifPath = "/home/lab/test/test.gif";
        FileOutputStream targetFile = new FileOutputStream(gifPath);
        FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(videpPath);
        grabber.start();
        Frame frame;
        int frames = grabber.getLengthInFrames();
        AnimatedGifEncoder encoder = new AnimatedGifEncoder();
        encoder.setFrameRate(frames);
        encoder.start(targetFile);
        Java2DFrameConverter converter = new Java2DFrameConverter();
        for (int i = 0 ; i < frames ; i++) {
            encoder.setDelay((int) grabber.getDelayedTime());
            grabber.setFrameNumber(i);
            frame = grabber.grabImage();
            encoder.addFrame(converter.convert(frame));
        }
        encoder.finish();
        targetFile.close();
        grabber.close();

　　pom依赖

　　因 javacv-platform依赖太重,实际引入的时候推荐指定系统版本的便可.开发机为64位Ubuntu,依赖以下

        <dependency>
            <groupId>org.bytedeco</groupId>
            <artifactId>javacv</artifactId>
            <version>1.4.3</version>
        </dependency>
        <dependency>
            <groupId>org.bytedeco.javacpp-presets</groupId>
            <artifactId>opencv</artifactId>
            <version>3.4.3-1.4.3</version>
            <classifier>linux-x86_64</classifier>
        </dependency>
        <dependency>
            <groupId>org.bytedeco.javacpp-presets</groupId>
            <artifactId>ffmpeg</artifactId>
            <version>4.0.2-1.4.3</version>
            <classifier>linux-x86_64</classifier>
        </dependency>
        <dependency>
            <groupId>org.bytedeco</groupId>
            <artifactId>javacpp</artifactId>
            <version>1.4.3</version>
        </dependency>
        <dependency>
            <groupId>org.bytedeco.javacpp-presets</groupId>
            <artifactId>ffmpeg</artifactId>
            <version>4.0.2-1.4.3</version>
            <classifier>linux-x86_64</classifier>
        </dependency>
        <!-- gif -->
        <dependency>
            <groupId>com.madgag</groupId>
            <artifactId>animated-gif-lib</artifactId>
            <version>1.4</version>
        </dependency>