c - 暂停 gstreamer 管道并进行更改后，返回播放状态时没有应用任何内容？

Question

下面的代码是使用 updsink 元素通过网络流式传输 mpeg4 视频(使用具有以下功能的 v4l2src 元素:宽度=640、高度=480、帧速率=30/1)，并且功能值应更改为 (按键盘上的“1”后，宽度=352，高度=288，帧速率=15/1)。我尝试通过在按下“1”后暂停管道，然后将上限重新设置为新值，然后使管道再次进入播放状态来做到这一点，但这对我来说不起作用。

我在暂停管道之前和进行更改之后打印了上限值，我可以看到对上限的更改已完成，但当管道再次进入播放状态时并未应用 ()

请帮忙......

您可以在运行以下代码之前在新终端中输入以下命令来播放此流:

gst-launch udpsrc 多播组=127.0.0.1 端口=8999 ! mpeg4视频解析! ffdec_mpeg4! ffmpeg颜色空间!自动视频接收器

======================

    #include <gst/gst.h>

    #include <glib.h>

    #include <stdio.h>

    #include <glib-object.h>




    static gboolean bus_call (GstBus *bus, GstMessage *msg, gpointer data)

    {

       GMainLoop *loop = (GMainLoop *) data;

       switch (GST_MESSAGE_TYPE (msg)) {

         case GST_MESSAGE_EOS:

             g_print ("End of stream\n");

             g_main_loop_quit (loop);

             break;




         case GST_MESSAGE_ERROR: {

             gchar *debug;

             GError *error;

             gst_message_parse_error (msg, &error, &debug);

             g_free (debug);

             g_printerr ("Error: %s\n", error->message);

             g_error_free (error);

             g_main_loop_quit (loop);

             break;

             }




         default: break;

         }

    return TRUE;

   }




int main (int argc, char *argv[])

{

   GMainLoop *loop;

   GstElement *pipeline, *source, *filter, *vrate, *encoder, *conv, *sink;

   GstBus *bus;

   GstCaps *filtercaps; 

   gint width, height, num, denom;

   const GstStructure *str;




   /* Initialisation */

   gst_init (&argc, &argv);

   loop = g_main_loop_new (NULL, FALSE);




   /* Check input arguments */

   if (argc != 2) {

     g_printerr ("Usage: %s <Ogg/Vorbis filename>\n", argv[0]);

     return -1;

   }




   /* Create gstreamer elements */

   pipeline = gst_pipeline_new ("video-player");

   source = gst_element_factory_make ("v4l2src", "file-source");

   vrate = gst_element_factory_make ("videorate", "video-rate");

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

   conv = gst_element_factory_make ("ffmpegcolorspace","converter");

   encoder = gst_element_factory_make ("ffenc_mpeg4","mpeg-decoder");

   sink = gst_element_factory_make ("udpsink","audio-output");







   if (!pipeline || !source || !filter || !vrate || !conv || !encoder || !sink) {

     g_printerr ("One element could not be created. Exiting.\n");

     return -1;

   }




   /* Set up the pipeline */

   /* we set the input filename to the source element */

   filtercaps = gst_caps_new_simple ("video/x-raw-yuv",

         "width", G_TYPE_INT, 640,

         "height", G_TYPE_INT, 480,

         "framerate", GST_TYPE_FRACTION, 30, 1,

         NULL);




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

   gst_caps_unref (filtercaps);

   g_object_set (G_OBJECT (encoder), "bitrate" , 384 ,  NULL);

   g_object_set (G_OBJECT (sink), "host" , argv[1] ,  NULL);

   g_object_set (G_OBJECT (sink), "port" , 8999 ,  NULL);

   g_object_set (G_OBJECT (sink), "async" , FALSE ,  NULL);






   /* we add a message handler */

   bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));

   gst_bus_add_watch (bus, bus_call, loop);

   gst_object_unref (bus);




   /* we add all elements into the pipeline */

   /* file-source | ogg-demuxer | vorbis-decoder | converter | alsa-output */

   gst_bin_add_many (GST_BIN (pipeline), source, vrate, filter, conv, encoder, sink, NULL);




   /* we link the elements together */

   /* file-source -> ogg-demuxer ~> vorbis-decoder -> converter -> alsa-output */

   gst_element_link_many (source, vrate, filter, conv, encoder,  sink, NULL);









   /* Set the pipeline to "playing" state*/

   g_print ("Now playing: \n");

   gst_element_set_state (pipeline, GST_STATE_PLAYING);





   /* Print out the frame size and rate */

   str = gst_caps_get_structure (filtercaps, 0);

   if (!gst_structure_get_int (str, "width", &width) || !gst_structure_get_int (str, "height", &height) || 

       !gst_structure_get_fraction (str, "framerate", &num, &denom)) 

         g_print ("No width/height available\n");

   g_print ("The video size of this set of capabilities is %dx%d and the frame rate is %d/%d\n", width, height, num, denom);









   /* Pausing the streame */ 

   int in;

   if (scanf ("%d", &in) == 1){

     g_print ("Now pausing: \n");

     gst_element_set_state (pipeline, GST_STATE_PAUSED );



     g_assert (GST_STATE (pipeline) == GST_STATE_PAUSED);

     g_assert (GST_STATE (source) == GST_STATE_PAUSED);

     g_assert (GST_STATE (filter) == GST_STATE_PAUSED);

     g_assert (GST_STATE (vrate) == GST_STATE_PAUSED);

     g_assert (GST_STATE (encoder) == GST_STATE_PAUSED);

     g_assert (GST_STATE (conv) == GST_STATE_PAUSED);

     g_assert (GST_STATE (sink) == GST_STATE_PAUSED);






     /* apply the alterations to the caps now */

     gst_caps_set_simple (filtercaps, "width", G_TYPE_INT, 352, "height", G_TYPE_INT, 288, "framerate", GST_TYPE_FRACTION, 15, 1, NULL);    





         /* Print out the frame size and rate after alteration*/

     str = gst_caps_get_structure (filtercaps, 0);

        if (!gst_structure_get_int (str, "width", &width) || !gst_structure_get_int (str, "height", &height) || 

        !gst_structure_get_fraction (str, "framerate", &num, &denom)) 

         g_print ("No width/height available\n");

     g_print ("The video size of this set of capabilities is %dx%d and the frame rate is %d/%d\n", width, height, num, denom);  



     /* set back to playing */

     gst_element_set_state (pipeline, GST_STATE_PLAYING);




     g_assert (GST_STATE (pipeline) == GST_STATE_PLAYING);

     g_assert (GST_STATE (source) == GST_STATE_PLAYING);

     g_assert (GST_STATE (filter) == GST_STATE_PLAYING);

     g_assert (GST_STATE (vrate) == GST_STATE_PLAYING);

     g_assert (GST_STATE (encoder) == GST_STATE_PLAYING);

     g_assert (GST_STATE (conv) == GST_STATE_PLAYING);

     g_assert (GST_STATE (sink) == GST_STATE_PLAYING);  



     }






   /* Iterate */

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

   g_main_loop_run (loop);





   /* Out of the main loop, clean up nicely */

   g_print ("Returned, stopping playback\n");

   gst_element_set_state (pipeline, GST_STATE_NULL);

   g_print ("Deleting pipeline\n");

   gst_object_unref (GST_OBJECT (pipeline));




   return 0;

}

干杯。

伊布

Answer 1

你错过了g_object_set(G_OBJECT(filter), "caps", filtercaps, NULL);的函数