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 [e-mail]
  */
 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\n");
             return;
         }

         if (avformat.avformat_find_stream_info(formatCtx, (AVDictionary) null) < 0) {
             System.out.println("Couldn't find stream information.\n");
             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.\n");
             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.\n");
             return;
         }

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

         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);
     }

 }