media/webrtc/trunk/test/linux/v4l2_file_player/v4l2_file_player.c

   1 /**
   2  * WebRTC Internal Tooling - Looping V4L2 player
   3  * Author: Patrik Höglund (phoglund@webrtc.org)
   4  *
   5  * This file implements a basic raw video file player which loops its input
   6  * file indefinitely. It is intended to be used with the v4l2loopback driver in
   7  * order to play the contents of a file as if it were a webcam. Therefore, this
   8  * program will write to a v4l2loopback device, say /dev/video1, and the driver
   9  * will then reflect the data unmodified to any reading processes.
  10  *
  11  * This program basically does the same thing as
  12  * gst-launch-0.10 -v filesrc location=resources/foreman_cif.yuv ! \
  13  *   videoparse width=352 height=288 ! v4l2sink device=/dev/video1
  14  *
  15  * , but with looping. Looping is unfortunately impossible to do with a regular
  16  * gstreamer pipeline, hence the existence of this program.
  17  *
  18  * It can be run something like this:
  19  * v4l2_file_player foreman_cif_short.yuv 352 288 /dev/video1 >& /dev/null
  20  *
  21  * The program might print warnings about failed ioctls (for instance for
  22  * VIDIOC_G_FMT), but that doesn't seem to be a problem.
  23  *
  24  * To test, you can run for instance mplayer tv:// -tv device=/dev/video1 and
  25  * verify that you see your video playing repeatedly.
  26  *
  27  * This code is based off the hello world example in the gstreamer manual.
  28  * You can find the original code in chapter 10, "Your First Application":
  29  * http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/
  30  */
  31
  32 #include <gst/gst.h>
  33 #include <glib.h>
  34
  35 typedef struct {
  36   GMainLoop* main_loop;
  37   GstElement* pipeline;
  38 } main_loop_and_pipeline_t;
  39
  40 static gboolean bus_call(GstBus *bus, GstMessage *msg, gpointer data) {
  41   main_loop_and_pipeline_t *main_loop_and_pipeline =
  42       (main_loop_and_pipeline_t*)data;
  43
  44   GMainLoop *loop = main_loop_and_pipeline->main_loop;
  45   GstElement *pipeline = main_loop_and_pipeline->pipeline;
  46
  47   switch (GST_MESSAGE_TYPE (msg)) {
  48     case GST_MESSAGE_EOS:
  49       /* Reached end of input video - restart */
  50       gst_element_set_state(pipeline, GST_STATE_READY);
  51       gst_element_set_state(pipeline, GST_STATE_PLAYING);
  52       break;
  53
  54     case GST_MESSAGE_ERROR: {
  55       gchar *debug;
  56       GError *error;
  57
  58       gst_message_parse_error(msg, &error, &debug);
  59       g_free(debug);
  60
  61       g_printerr("Error: %s\n", error->message);
  62       g_error_free(error);
  63
  64       g_main_loop_quit(loop);
  65       break;
  66     }
  67     default:
  68       break;
  69   }
  70
  71   return TRUE;
  72 }
  73
  74 int main(int argc, char *argv[]) {
  75   gst_init(&argc, &argv);
  76
  77   GMainLoop *main_loop = g_main_loop_new(NULL, FALSE);
  78
  79   /* Check input arguments */
  80   if (argc != 5 || atoi(argv[2]) == 0 || atoi(argv[3]) == 0) {
  81     g_printerr("Usage: %s <filename> <width> <height> <device>\n\n", argv[0]);
  82     g_printerr("Arguments:\n");
  83     g_printerr("  filename: Path to the video file.\n");
  84     g_printerr("  width:    Video width.\n");
  85     g_printerr("  height:   Video height.\n");
  86     g_printerr("  device:   Device to write to (like /dev/video1).\n");
  87     return -1;
  88   }
  89
  90   /* Create gstreamer pipeline elements. */
  91   GstElement *pipeline = gst_pipeline_new("looping-video-player");
  92   GstElement *source = gst_element_factory_make("filesrc", "file-source");
  93   GstElement *parse = gst_element_factory_make("videoparse", "video-parse");
  94   GstElement *v4l2_sink = gst_element_factory_make("v4l2sink", "v4l2-sink");
  95
  96   if (!pipeline || !source || !parse || !v4l2_sink) {
  97     g_printerr("One GST element could not be created. Exiting.\n");
  98     return -1;
  99   }
 100
 101   /* Set up input parameters. */
 102   g_object_set(G_OBJECT (source), "location", argv[1], NULL);
 103   g_object_set(G_OBJECT (parse), "width", atoi(argv[2]), NULL);
 104   g_object_set(G_OBJECT (parse), "height", atoi(argv[3]), NULL);
 105   g_object_set(G_OBJECT (v4l2_sink), "device", argv[4], NULL);
 106
 107   /* Add a callback to we can react to end-of-stream and errors. */
 108   main_loop_and_pipeline_t main_loop_and_pipeline;
 109   main_loop_and_pipeline.main_loop = main_loop;
 110   main_loop_and_pipeline.pipeline = pipeline;
 111
 112   GstBus *bus = gst_pipeline_get_bus(GST_PIPELINE (pipeline));
 113   gst_bus_add_watch(bus, bus_call, &main_loop_and_pipeline);
 114   gst_object_unref(bus);
 115
 116   /* Assemble the pipeline. */
 117   gst_bin_add_many(GST_BIN (pipeline), source, parse, v4l2_sink, NULL);
 118   gst_element_link(source, parse);
 119   gst_element_link(parse, v4l2_sink);
 120
 121   /* Start playing. */
 122   gst_element_set_state(pipeline, GST_STATE_PLAYING);
 123   g_main_loop_run(main_loop);
 124
 125   /* Never reached. */
 126   return 0;
 127 }