用JavaCV改写“100行代码实现最简单的基于FFMPEG+SDL的视频播放器 ”

FFMPEG的文档少，JavaCV的文档就更少了。从网上找到这篇100行代码实现最简单的基于FFMPEG+SDL的视频播放器 。地址是http://blog.csdn.net/leixiaohua1020/article/details/8652605。

用JavaCV重新实现并使用opencv_highgui进行显示。

import com.googlecode.javacpp.IntPointer;
import com.googlecode.javacpp.Pointer;
import com.googlecode.javacv.cpp.avcodec;
import com.googlecode.javacv.cpp.avcodec.AVPacket;
import com.googlecode.javacv.cpp.avcodec.AVPicture;
import com.googlecode.javacv.cpp.avformat;
import com.googlecode.javacv.cpp.avutil;
import com.googlecode.javacv.cpp.avutil.AVDictionary;
import com.googlecode.javacv.cpp.opencv_core;
import static com.googlecode.javacv.cpp.opencv_core.IPL_DEPTH_8U;
import com.googlecode.javacv.cpp.opencv_core.IplImage;
import static com.googlecode.javacv.cpp.opencv_core.cvSize;
import com.googlecode.javacv.cpp.opencv_highgui;
import static com.googlecode.javacv.cpp.opencv_highgui.cvDestroyWindow;
import static com.googlecode.javacv.cpp.opencv_highgui.cvNamedWindow;
import com.googlecode.javacv.cpp.swscale;
import com.googlecode.javacv.cpp.swscale.SwsContext;

/**
 *
 * @author cuizhenfu@gmail.com
 */
public class DecodingH264 {

    public static void main(String[] args) {
        String filePath = "Images/butterfly.h264";

        // Register all formats and codes
        avformat.av_register_all();
        avcodec.avcodec_register_all();

        // Open video file
        avformat.AVFormatContext formatCtx = avformat.avformat_alloc_context();
        if (avformat.avformat_open_input(formatCtx, filePath, null, null) != 0) {
            System.out.println("无法打开文件
");
            return;
        }

        if (avformat.avformat_find_stream_info(formatCtx, (AVDictionary) null) < 0) {
            System.out.println("Couldn't find stream information.
");
            return;
        }
        int videoIndex = -1;
        for (int i = 0; i < formatCtx.nb_streams(); i++) {
            if (formatCtx.streams(i).codec().codec_type() == avutil.AVMEDIA_TYPE_VIDEO) {
                videoIndex = i;
                break;
            }
        }

        if (videoIndex == -1) {
            System.out.println("Didn't find a video stream.
");
            return;
        }

        avcodec.AVCodecContext codecCtx = formatCtx.streams(videoIndex).codec();
        avcodec.AVCodec codec = avcodec.avcodec_find_decoder(codecCtx.codec_id());
        if (codec == null) {
            System.out.println("Codec not found.
");
            return;
        }

        if (avcodec.avcodec_open2(codecCtx, codec, (AVDictionary) null) < 0) {
            System.out.println("Could not open codec.
");
        }

        avutil.AVFrame frame = avcodec.avcodec_alloc_frame();
        avutil.AVFrame frameRGB = avcodec.avcodec_alloc_frame();
        
        // 注意AVPicture的构造方法，参考http://blog.csdn.net/wahrlr/article/details/21970755
        // 注意avutil.av_malloc的返回值（用Pointer代替uint8_t*）
        int nunBytes = avcodec.avpicture_get_size(avutil.AV_PIX_FMT_RGB24, codecCtx.width(), codecCtx.height());
        Pointer outBuffer = avutil.av_malloc(nunBytes);
        avcodec.avpicture_fill(new AVPicture(frameRGB), outBuffer.asByteBuffer(), avutil.AV_PIX_FMT_RGB24, codecCtx.width(), codecCtx.height());
        
        avformat.av_dump_format(formatCtx, 0, filePath, 0);
        
        SwsContext img_convert_ctx = swscale.sws_getContext(codecCtx.width(), codecCtx.height(), codecCtx.pix_fmt(), codecCtx.width(), codecCtx.height(), avutil.AV_PIX_FMT_RGB24, swscale.SWS_BICUBIC, null, null, (double[])null);
        
        AVPacket packet = new AVPacket();
        int y_size = codecCtx.width() * codecCtx.height();  
        avcodec.av_new_packet(packet, y_size);
        cvNamedWindow("butterfly.h264");
        IplImage showImage = opencv_core.cvCreateImage(cvSize(codecCtx.width(),codecCtx.height()), IPL_DEPTH_8U, 3);        
        while(avformat.av_read_frame(formatCtx, packet) >= 0) {
            if(packet.stream_index() == videoIndex) {
                IntPointer ip = new IntPointer();
                int ret = avcodec.avcodec_decode_video2(codecCtx, frame, ip, packet);
                if(ret < 0) {
                    System.out.println("解码错误");
                    return;
                }
                if(ip.get() != 0) {
                    swscale.sws_scale(img_convert_ctx, frame.data(), frame.linesize(), 0, codecCtx.height(), frameRGB.data(), frameRGB.linesize());
            
                    showImage.imageData(frameRGB.data(0));
                    showImage.widthStep(frameRGB.linesize().get(0));
                    
                    opencv_highgui.cvShowImage("butterfly.h264", showImage);
                    opencv_highgui.cvWaitKey(25);
                }
            }
            avcodec.av_free_packet(packet);
        }
        
        showImage.release();
        cvDestroyWindow("butterfly.h264");
        avutil.av_free(frameRGB);
        avcodec.avcodec_close(codecCtx);
        avformat.avformat_close_input(formatCtx);        
    }
    
}