CentOS 下通过 JavaCPP 调用 FFMPEG

1. Java 与 FFMPEG

FFMPEG 是一个广泛用于媒体处理的库，在Java的世界里，处理视频的能力相当弱，于是有很大需求需要Java 调用 FFMPEG。

Java 调用C 的方式有很多，可以用最原始的JNI方式，也可以JNA方式，还可以是命令行。

采用命令行的方式比较简单，不过有很大局限性，尤其是涉及到视频的处理和分析的时候，比如要取出某个packet，然后进行处理。

这里介绍的是用JavaCPP 调用 ffmpeg 库的方式，而不是命令行模式。

JavaCPP的源码在这里：https://github.com/bytedeco/javacpp

基于JavaCPP的项目

1）JavaCV，是做图形图像的，有人脸识别、增强现实AR 等开源算法，非常不错

项目主页是：https://github.com/bytedeco/javacv

2）JavaAV 封装了FFMPEG的java 接口

项目主页：https://github.com/hoary/JavaAV

2. JavaCPP Presets

为了方便使用，JavaCPP下面有个presets项目，主页是 https://github.com/bytedeco/javacpp-presets，将一些常用的项目都编译好了以方便使用。
集成的项目包括：
• OpenCV 2.4.9 http://opencv.org/downloads.html
• FFmpeg 2.3.x http://ffmpeg.org/download.html
• FlyCapture 2.6.x http://ww2.ptgrey.com/sdk/flycap
• libdc1394 2.1.x or 2.2.x http://sourceforge.net/projects/libdc1394/files/
• libfreenect 0.5 https://github.com/OpenKinect/libfreenect
• videoInput 0.200 https://github.com/ofTheo/videoInput/tree/update2013
• ARToolKitPlus 2.3.0 https://launchpad.net/artoolkitplus
• flandmark 1.07 http://cmp.felk.cvut.cz/~uricamic/flandmark/#download
• FFTW 3.3.4 http://www.fftw.org/download.html
• GSL 1.16 http://www.gnu.org/software/gsl/#downloading
• LLVM 3.4.2 http://llvm.org/releases/download.html
• Leptonica 1.71 http://www.leptonica.org/download.html
• Tesseract 3.03-rc1 https://code.google.com/p/tesseract-ocr/

包含的平台有： android-arm, android-x86, linux-x86, linux-x86_64, macosx-x86_64, windows-x86, windows-x86_64，

但需要注意：这里的 linux-x86_64 是基于Fedora 平台的，无法在 CentOS下使用。

3. 在CentOS下编译
1）安装JDK
2）安装 apache-maven 2/3

3) 安装 gcc,gcc+,gcc-c++,yasm

yum -y install yasm gcc+ gcc-c++

4) 获取源码

git clone http://github.com/bytedeco/javacpp-presets
5) 编译 ffmpeg

cd javacpp-presets/
./cppbuild.sh -platform linux-x86_64 install ffmpeg

6) 编译 jni 和相关jar

mvn install --projects ffmpeg

7) 编译完成后，会在 ffmpeg 的lib上生成相关 .so ，javacpp-presets/targets 下生成相关的jar

4. 测试
1）将相关的 .so 复制到 /lib64 目录下，或者通过 -Djava.library.path 指定到.so 所在目录
2）拷贝一个实例用来测试，

public class Tutorial01 {  
  
    static void SaveFrame(AVFrame pFrame, int width, int height, int iFrame)  
            throws IOException {  
        // Open file  
        OutputStream stream = new FileOutputStream("frame" + iFrame + ".ppm");  
  
        // Write header  
        stream.write(("P6\n" + width + " " + height + "\n255\n").getBytes());  
  
        // Write pixel data  
        BytePointer data = pFrame.data(0);  
        byte[] bytes = new byte[width * 3];  
        int l = pFrame.linesize(0);  
        for (int y = 0; y < height; y++) {  
            data.position(y * l).get(bytes);  
            stream.write(bytes);  
        }  
  
        // Close file  
        stream.close();  
    }  
  
    public static void main(String[] args) throws IOException {  
        AVFormatContext pFormatCtx = new AVFormatContext(null);  
        int i, videoStream;  
        AVCodecContext pCodecCtx = null;  
        AVCodec pCodec = null;  
        AVFrame pFrame = null;  
        AVFrame pFrameRGB = null;  
        AVPacket packet = new AVPacket();  
        int[] frameFinished = new int[1];  
        int numBytes;  
        BytePointer buffer = null;  
  
        AVDictionary optionsDict = null;  
        SwsContext sws_ctx = null;  
  
        if (args.length < 1) {  
            args = new String[] { "/root/test.ts" };  
            // System.out.println("Please provide a movie file");  
            // System.exit(-1);  
        }  
        // Register all formats and codecs  
        av_register_all();  
  
        // Open video file  
        if (avformat_open_input(pFormatCtx, args[0], null, null) != 0) {  
            System.exit(-1); // Couldn't open file  
        }  
  
        // Retrieve stream information  
        if (avformat_find_stream_info(pFormatCtx, (PointerPointer) null) < 0) {  
            System.exit(-1); // Couldn't find stream information  
        }  
  
        // Dump information about file onto standard error  
        av_dump_format(pFormatCtx, 0, args[0], 0);  
  
        // Find the first video stream  
        videoStream = -1;  
        for (i = 0; i < pFormatCtx.nb_streams(); i++) {  
            if (pFormatCtx.streams(i).codec().codec_type() == AVMEDIA_TYPE_VIDEO) {  
                videoStream = i;  
                break;  
            }  
        }  
        if (videoStream == -1) {  
            System.exit(-1); // Didn't find a video stream  
        }  
  
        // Get a pointer to the codec context for the video stream  
        pCodecCtx = pFormatCtx.streams(videoStream).codec();  
  
        // Find the decoder for the video stream  
        pCodec = avcodec_find_decoder(pCodecCtx.codec_id());  
        if (pCodec == null) {  
            System.err.println("Unsupported codec!");  
            System.exit(-1); // Codec not found  
        }  
        // Open codec  
        if (avcodec_open2(pCodecCtx, pCodec, optionsDict) < 0) {  
            System.exit(-1); // Could not open codec  
        }  
  
        // Allocate video frame  
        pFrame = av_frame_alloc();  
  
        // Allocate an AVFrame structure  
        pFrameRGB = av_frame_alloc();  
        if (pFrameRGB == null) {  
            System.exit(-1);  
        }  
  
        // Determine required buffer size and allocate buffer  
        numBytes = avpicture_get_size(AV_PIX_FMT_RGB24, pCodecCtx.width(),  
                pCodecCtx.height());  
        buffer = new BytePointer(av_malloc(numBytes));  
  
        sws_ctx = sws_getContext(pCodecCtx.width(), pCodecCtx.height(),  
                pCodecCtx.pix_fmt(), pCodecCtx.width(), pCodecCtx.height(),  
                AV_PIX_FMT_RGB24, SWS_BILINEAR, null, null,  
                (DoublePointer) null);  
  
        // Assign appropriate parts of buffer to image planes in pFrameRGB  
        // Note that pFrameRGB is an AVFrame, but AVFrame is a superset  
        // of AVPicture  
        avpicture_fill(new AVPicture(pFrameRGB), buffer, AV_PIX_FMT_RGB24,  
                pCodecCtx.width(), pCodecCtx.height());  
  
        // Read frames and save first five frames to disk  
        i = 0;  
        while (av_read_frame(pFormatCtx, packet) >= 0) {  
            // Is this a packet from the video stream?  
            if (packet.stream_index() == videoStream) {  
                // Decode video frame  
                avcodec_decode_video2(pCodecCtx, pFrame, frameFinished, packet);  
  
                // Did we get a video frame?  
                if (frameFinished[0] != 0) {  
                    // Convert the image from its native format to RGB  
                    sws_scale(sws_ctx, pFrame.data(), pFrame.linesize(), 0,  
                            pCodecCtx.height(), pFrameRGB.data(),  
                            pFrameRGB.linesize());  
  
                    // Save the frame to disk  
                    if (++i <= 5) {  
                        SaveFrame(pFrameRGB, pCodecCtx.width(),  
                                pCodecCtx.height(), i);  
                    }  
                }  
            }  
  
            // Free the packet that was allocated by av_read_frame  
            av_free_packet(packet);  
        }  
  
        // Free the RGB image  
        av_free(buffer);  
        av_free(pFrameRGB);  
  
        // Free the YUV frame  
        av_free(pFrame);  
  
        // Close the codec  
        avcodec_close(pCodecCtx);  
  
        // Close the video file  
        avformat_close_input(pFormatCtx);  
  
        System.exit(0);  
    }  
}

4）运行实例，得到输出结果：

Input #0, mpegts, from '/root/test.ts':
Duration: 00:03:20.02, start: 0.056778, bitrate: 1455 kb/s
Program 1
Metadata:
service_name : jVideo
service_provider: jTeam
Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 960x540 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
Stream #0:1[0x101]: Audio: aac ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 66 kb/s

原文：http://blog.csdn.net/maoxiang/article/details/38388387

CentOS 下通过 JavaCPP 调用 FFMPEG

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