Videomixer 在源上失败，而不是在 Videotestsrc 上失败

我想在一个视频文件中同时播放两个不同的本地视频文件 窗户。下面的代码在没有解复用器和解码器的情况下工作正常。

    static void play_video(){

    GMainLoop *loop;
    GstElement *pipeline,*videomixer;
    GstElement *src,*sink,*filter,*csp,*videobox;
    GstElement *src1,*filter1,*csp1,*videobox1;
    GstElement *srcb,*filterb,*cspb,*videoboxb;
    GstCaps *filtercaps,*filtercaps1,*filtercapsb;
    GstPad *pad,*pad1;

    const char pattern = "snow";

    loop = g_main_loop_new(NULL, FALSE);

    pipeline = gst_pipeline_new("my-pipeline");

    src = gst_element_factory_make ("videotestsrc","src");
    src1 = gst_element_factory_make ("videotestsrc","src1");

    g_object_set (G_OBJECT (src), "pattern", 10, NULL);

    filter = gst_element_factory_make("capsfilter","filter");
    filter1 = gst_element_factory_make("capsfilter","filter1");

    csp = gst_element_factory_make("ffmpegcolorspace","csp");
    csp1 = gst_element_factory_make("ffmpegcolorspace","csp1");

    /**/

    videobox=gst_element_factory_make("videobox","videobox");
    g_object_set(videobox,"top",0,"bottom",0,"left",0,"right",0,NULL);
    videobox1=gst_element_factory_make("videobox","videobox1");
    g_object_set(videobox1,"top",-20,"bottom",0,"left",0,"right",0,NULL);

    videomixer=gst_element_factory_make("videomixer","videomixer");



      /**/
      sink = gst_element_factory_make("xvimagesink","sink");
       if(sink == NULL)
       sink = gst_element_factory_make("ximagesink","sink");
       if(sink == NULL)
       g_error("'ximagesink' yaratılamadı.");




    gst_bin_add_many(GST_BIN(pipeline),src,filter,videobox,videomixer,csp,sink,
                src1,filter1,videobox1,csp1,NULL);



    gst_element_link_many(src,filter,csp,videobox,videomixer,NULL);
    gst_element_link_many(src1,filter1,csp1,videobox1,videomixer,NULL);



     /*
     videotestsrc pattern="snow" ! video/x-raw-yuv, framerate=1/1, width=350,
height=250 ! \
     textoverlay font-desc="Sans 24" text="CAM2" valign=top halign=left
shaded-background=true ! \
     videobox border-alpha=0 top=-200 left=-450 ! mix. \


    */


     gst_element_link_many(videomixer,sink,NULL);

     filtercaps = gst_caps_new_simple ("video/x-raw-rgb",
          "width", G_TYPE_INT, 1024,
          "height", G_TYPE_INT, 768,
          "framerate", GST_TYPE_FRACTION, 25, 1,
          "bpp", G_TYPE_INT, 16,
          "depth", G_TYPE_INT, 16,
          "endianness", G_TYPE_INT, G_BYTE_ORDER,
          NULL);

     filtercaps1 = gst_caps_new_simple ("video/x-raw-rgb",
          "width", G_TYPE_INT, 200,
          "height", G_TYPE_INT, 500,
          "framerate", GST_TYPE_FRACTION, 25, 1,
          "bpp", G_TYPE_INT, 16,
          "depth", G_TYPE_INT, 16,
          "endianness", G_TYPE_INT, G_BYTE_ORDER,
          NULL);

      g_object_set (G_OBJECT (filter), "caps", filtercaps, NULL);
      gst_caps_unref (filtercaps);

      g_object_set (G_OBJECT (filter1), "caps", filtercaps1, NULL);
      gst_caps_unref (filtercaps1);

      /*pad = gst_element_get_pad (src, "src");
      pad1 = gst_element_get_pad (src1, "src1");

      //gst_pad_add_buffer_probe (pad, G_CALLBACK (cb_have_data), NULL);
      //gst_pad_add_buffer_probe (pad1, G_CALLBACK (cb_have_data), NULL);
      //gst_object_unref (pad);
      //gst_object_unref (pad1);*/

      /* run */
      gst_element_set_state (pipeline, GST_STATE_PLAYING);

      /* wait until it's up and running or failed */
       if (gst_element_get_state (pipeline, NULL, NULL, -1) ==
       GST_STATE_CHANGE_FAILURE) {
       g_error ("Failed to go into PLAYING state");
      }

      g_print ("Running ...\n");
      g_main_loop_run (loop);

     /* exit */
     gst_element_set_state (pipeline, GST_STATE_NULL);
     gst_object_unref (pipeline);
     }

问题是当我用 filesrc 替换 videotestsrc 时它失败并且 我收到的唯一错误消息是“无法在信号销毁时查找对象 NULL” 对象窗口”。我不是 gstreamer 专家，我的观点是我是 设置解复用器和解码器失败。

static void play_video5(){


       GMainLoop *loop;
   GstElement *pipeline,*videomixer;
   GstElement *src,*sink,*filter,*csp,*videobox;
   GstElement *src1,*filter1,*csp1,*videobox1;
   GstElement *srcb,*filterb,*cspb,*videoboxb;
   GstCaps *filtercaps,*filtercaps1,*filtercapsb;
   GstPad *pad,*pad1;

       GstElement *demux,*decoder;

   const char pattern = "snow";

   loop = g_main_loop_new(NULL, FALSE);

   pipeline = gst_pipeline_new("my-pipeline");


       //Source
   src = gst_element_factory_make ("videotestsrc","src");

       src1 = gst_element_factory_make ("filesrc","src1");
       g_object_set (G_OBJECT (src1), "location", "file:///root/yu.mp4", NULL);

       //Demux

       demux = gst_element_factory_make ("mpegdemux", "demux");

       //Decoder
       decoder = gst_element_factory_make ("decodebin", "decoder");
//      decoder = gst_element_factory_make ("ffdec_mpeg4","mpeg4-decoder");

       //Filter
   filter = gst_element_factory_make("capsfilter","filter");
   filter1 = gst_element_factory_make("capsfilter","filter1");

       //Colorspace
   csp = gst_element_factory_make("ffmpegcolorspace","csp");
   csp1 = gst_element_factory_make("ffmpegcolorspace","csp1");


       //Videobox
   videobox=gst_element_factory_make("videobox","videobox");
   g_object_set(videobox,"top",0,"bottom",0,"left",0,"right",0,NULL);
   videobox1=gst_element_factory_make("videobox","videobox1");
   g_object_set(videobox1,"top",-20,"bottom",0,"left",0,"right",0,NULL);

       //videomixer
   videomixer=gst_element_factory_make("videomixer","videomixer");

       //Sink
   sink = gst_element_factory_make("xvimagesink","sink");
   if(sink == NULL)
       sink = gst_element_factory_make("ximagesink","sink");
       if(sink == NULL)
       g_error("'ximagesink' yaratılamadı.");


       //Add to Bin
   gst_bin_add_many(GST_BIN(pipeline),src,filter,videobox,videomixer,csp,
                src1,decoder,filter1,videobox1,csp1,sink,NULL);

       //Link Elements
       gst_element_link(src,filter);
       gst_element_link(filter,csp);
       gst_element_link(csp,videobox);
       gst_element_link(videobox, videomixer);

       gst_element_link(src1,decoder);
       gst_element_link(decoder,filter1);
//      gst_element_link(decoder,csp1);
       gst_element_link(filter1,csp1);
       gst_element_link(csp1,videobox1);
       gst_element_link(videobox1, videomixer);

       gst_element_link(videomixer,sink);



       //Cap definition
   filtercaps = gst_caps_new_simple ("video/x-raw-rgb",
          "width", G_TYPE_INT, 1024,
          "height", G_TYPE_INT, 768,
          "framerate", GST_TYPE_FRACTION, 25, 1,
          "bpp", G_TYPE_INT, 16,
          "depth", G_TYPE_INT, 16,
          "endianness", G_TYPE_INT, G_BYTE_ORDER,
          NULL);

   filtercaps1 = gst_caps_new_simple ("video/x-raw-yuv",
          "width", G_TYPE_INT, 640,
          "height", G_TYPE_INT, 480,
          "framerate", GST_TYPE_FRACTION, 25, 1,
          /*"bpp", G_TYPE_INT, 16,
          "depth", G_TYPE_INT, 16,
          "endianness", G_TYPE_INT, G_BYTE_ORDER,*/
          NULL);

       //Cap to Filter
   g_object_set (G_OBJECT (filter), "caps", filtercaps, NULL);
   gst_caps_unref (filtercaps);

   g_object_set (G_OBJECT (filter1), "caps", filtercaps1, NULL);
   gst_caps_unref (filtercaps1);


   /* run */
   gst_element_set_state (pipeline, GST_STATE_PLAYING);

   /* wait until it's up and running or failed */
   if (gst_element_get_state (pipeline, NULL, NULL, -1) ==
GST_STATE_CHANGE_FAILURE) {
       g_error ("Failed to go into PLAYING state");
   }

   g_print ("Running ...\n");
   g_main_loop_run (loop);

   /* exit */
   gst_element_set_state (pipeline, GST_STATE_NULL);
   gst_object_unref (pipeline);
}

欢迎任何想法或更正。

几个问题：

• filesrc 不采用 uri，而是采用文件路径
• /* 等到它启动并运行或失败 */ + 下面的代码不是必需的，最好在总线上监听错误和警告消息
• “在对象窗口信号销毁时无法查找对象 NULL”与 gstreamer 无关
• 不需要整个 videobox 业务，因为 videomixer 的 pad 具有 xpos、ypos 和 zorder 属性