Looping a video with gstreamer and gst-launch?

问题

I am able to play a video on the command line with gstreamer's gst-launch like this:

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

This plays the first 2 seconds of the file in /tmp/myfile.mov, afterwards the video playback stops. Is there anyway to get this to loop repeatidly? i.e. turn the 2 second long gnlfilesource into an infinite length video that plays those 2 seconds again and again and again?

回答1:

Assuming bash...

Wrap it in a while-loop?

while true; do [your command]; done

where true does nothing sucessfully, i.e.

true: true
    Return a successful result.

    Exit Status:
    Always succeeds.

It allows you to create infinite loops, e.g.

$ while true; do echo "run..."; sleep 1; done
run...
run...
run...
run...
run...
...

回答2:

If using gst-launch then you may have to use while true; do [your command]; done as Fredrik has stated. However if interested in C code, I have written a code which may help you. Looping of video every 2 seconds from the beginning of the file at the end of the stream of first run.

  //(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;
}

Update: See the following link http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/chapter-dataaccess.html

[Section 19.1.2. Play a region of a media file]. This could be used in conjugation with my code.

回答3:

This seems to be possible with multifilesrc plugin,

gst-launch-1.0 multifilesrc location=alien-age.mpg loop=true ! decodebin ! autovideosink

Seems to be added back in June 2011.

回答4:

According to folks on the #gstreamer IRC channel, you can't do this with gstreamer itself, you'd need something outside the gstreamer pipeline to loop it.

来源：https://stackoverflow.com/questions/6833147/looping-a-video-with-gstreamer-and-gst-launch