linux - 使用 gstreamer 和 gst-launch 循环播放视频？

Question

我可以像这样使用 gstreamer 的 gst-launch 在命令行上播放视频:

gst-launch gnlfilesource location=file:///tmp/myfile.mov start=0 duration=2000000000 ! autovideosink

这会播放/tmp/myfile.mov 中文件的前 2 秒，之后视频播放停止。有没有办法让它重复循环？即将 2 秒长的 gnlfilesource 变成一个无限长的视频，一次又一次地播放这 2 秒？

Answer 1

如果使用 gst-launch 那么您可能必须使用 while true;执行[你的命令]；正如 Fredrik 所说，完成了。但是，如果对 C 代码感兴趣，我编写了一个代码，可能会对您有所帮助。在第一次运行的流结束时从文件开头开始每 2 秒循环一次视频。

  //(c) 2011 enthusiasticgeek
  // This code is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

#include <gst/gst.h>

gboolean bus_callback(GstBus *bus, GstMessage *msg, gpointer data)
{
    GstElement *play = GST_ELEMENT(data);
    switch (GST_MESSAGE_TYPE(msg))
    {
    case GST_MESSAGE_EOS:
        /* restart playback if at end */
        if (!gst_element_seek(play, 
                    1.0, GST_FORMAT_TIME, GST_SEEK_FLAG_FLUSH,
                    GST_SEEK_TYPE_SET,  2000000000, //2 seconds (in nanoseconds)
                    GST_SEEK_TYPE_NONE, GST_CLOCK_TIME_NONE)) {
            g_print("Seek failed!\n");
        }
        break;
    default:
        break;
    }
    return TRUE;
}

gint
main (gint   argc,
      gchar *argv[])
{
  GMainLoop *loop;
  GstElement *play;
  GstBus *bus;

  /* init GStreamer */
  gst_init (&argc, &argv);
  loop = g_main_loop_new (NULL, FALSE);

  /* make sure we have a URI */
  if (argc != 2) {
    g_print ("Usage: %s <URI>\n", argv[0]);
    return -1;
  }

  /* set up */
  play = gst_element_factory_make ("playbin", "play");
  g_object_set (G_OBJECT (play), "uri", argv[1], NULL);

  bus = gst_pipeline_get_bus (GST_PIPELINE (play));
  gst_bus_add_watch (bus, bus_callback, play);
  gst_object_unref (bus);

  gst_element_set_state (play, GST_STATE_PLAYING);

  /* now run */
  g_main_loop_run (loop);

  /* also clean up */
  gst_element_set_state (play, GST_STATE_NULL);
  gst_object_unref (GST_OBJECT (play));

  return 0;
}

更新:请参阅以下链接 http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/chapter-dataaccess.html

[第 19.1.2 节。播放媒体文件的一个区域]。这可以与我的代码结合使用。