CentOS 由 JavaCPP 转让 FFMPEG

1. Java 与 FFMPEG

FFMPEG 它是一种广泛使用的媒体处理库，于Java天地，处理视频较弱的能力，因此，有非常大的需求需求Java 转让 FFMPEG。

Java 转让C 的方式有非常多。能够用最原始的JNI方式，也能够JNA方式。还能够是命令行。

採用命令行的方式比較简单。只是有非常大局限性，尤其是涉及到视频的处理和分析的时候。比方要取出某个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的源代码在这里：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，很不错

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以下有个presets项目，主页是 https://github.com/bytedeco/javacpp-presets。将一些经常使用的项目都编译好了以方便使用。
集成的项目包含：
• 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/

包括的平台有： android-arm, android-x86, linux-x86, linux-x86_64, macosx-x86_64, windows-x86, windows-x86_64，

但须要注意：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) 获取源代码

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) 编译完毕后。会在 ffmpeg 的lib上生成相关 .so 。javacpp-presets/targets 下生成相关的jar

4. 測试
1）将相关的 .so 拷贝到 /lib64 文件夹下，或者通过 -Djava.library.path 指定到.so 所在文件夹
2）拷贝一个实例用来測试。

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
" + width + " " + height + "
255
").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）执行实例，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