Looping a video with gstreamer and gst-launch?

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.

multifilesrc is the easiest way, but it won't work on media files that have "Media length" known. you can loop on any video files only if file does not have any information about the time or length.

Open your file with any media player, if it shows media length or if you can seek the file forward or backward, that means it knows the media length and multifilesrc won't loop it.

How to convert video file into file without time track (stream file) with GStreamer:

you need to run two pipelines on command line, first run the recorder:

gst-launch-1.0 udpsrc port=10600 ! application/x-rtp-stream ! rtpstreamdepay name=pay1 ! rtph264depay ! h264parse ! video/x-h264,alignment=nal ! filesink location=my_timeless_file.mp4

it starts and waits for incoming stream.

on another terminal run the play pipeline:

gst-launch-1.0 filesrc location=my_file_with_time_track ! queue ! decodebin ! videoconvert ! x264enc ! h264parse config-interval=-1 ! rtph264pay pt=96 ! rtpstreampay name=pay0 ! udpsink host=127.0.0.1 port=10600

play pipeline starts and eventually terminates when it streamed whole file, now go back to the first command line and terminate recording pipeline with Ctrl+C.

(instead of udpsrc/udpsink you can use any other mechanisms to make the stream, like appsrc/appsink)

Now you have a new file which can be used in multifilesrc with loop:

gst-launch-1.0 multifilesrc location=my_timeless_file.mp4 loop=true ! queue ! decodebin ! videoconvert ! ximagesink

Why multifilesrc does not loop files with known length?

Because when length of media is known it sends EOS message downstream and causes whole pipeline going to state NULL, by removing that information when it reaches end of file (byte stream) it tries to find next file to play (remember it is "multi" file source, and by default can accept wildcard location like "image_%d.png"). When there is no wildcard to point to the next file, it loops back to only known file.

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.

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.