1 /* GStreamer

     2  *

     3  * appsrc-stream2.c: example for using appsrc in streaming mode.

     4  *

     5  * Copyright (C) 2008 Wim Taymans <wim.taymans@gmail.com>

     6  *

     7  * This library is free software; you can redistribute it and/or

     8  * modify it under the terms of the GNU Library General Public

     9  * License as published by the Free Software Foundation; either

    10  * version 2 of the License, or (at your option) any later version.

    11  *

    12  * This library is distributed in the hope that it will be useful,

    13  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    15  * Library General Public License for more details.

    16  *

    17  * You should have received a copy of the GNU Library General Public

    18  * License along with this library; if not, write to the

    19  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

    20  * Boston, MA 02111-1307, USA.

    21  */

    22 

    23 #ifdef HAVE_CONFIG_H

    24 #include "config.h"

    25 #endif

    26 

    27 #include <gst/gst.h>

    28 

    29 #include <stdio.h>

    30 #include <string.h>

    31 #include <stdlib.h>

    32 

    33 GST_DEBUG_CATEGORY (appsrc_playbin_debug);

    34 #define GST_CAT_DEFAULT appsrc_playbin_debug

    35 

    36 /*

    37  * an example application of using appsrc in streaming pull mode. When the

    38  * appsrc request data with the need-data signal, we retrieve a buffer of an

    39  * arbitrary size and push it to appsrc.

    40  *

    41  * This example keeps the internal buffer queue of appsrc to a minimal size,

    42  * only feeding data to appsrc when needed.

    43  *

    44  * This is a good example how one would deal with a live resource, such as a udp

    45  * socket where one would feed the most recently acquired buffer to appsrc. 

    46  *

    47  * Usually one would timestamp the buffers with the running_time of the

    48  * pipeline or configure the appsrc to do timestamping by setting the 

    49  * do-timestamp property to TRUE.

    50  *

    51  * Appsrc in streaming mode (the default) does not support seeking so we don't

    52  * have to handle any seek callbacks.

    53  *

    54  * Some formats are able to estimate the duration of the media file based on the

    55  * file length (mp3, mpeg,..), others report an unknown length (ogg,..).

    56  */

    57 typedef struct _App App;

    58 

    59 struct _App

    60 {

    61   GstElement *playbin;

    62   GstElement *appsrc;

    63 

    64   GMainLoop *loop;

    65 

    66   GMappedFile *file;

    67   guint8 *data;

    68   gsize length;

    69   guint64 offset;

    70 };

    71 

    72 App s_app;

    73 

    74 #define CHUNK_SIZE  4096

    75 

    76 /* This method is called by the need-data signal callback, we feed data into the

    77  * appsrc.

    78  */

    79 static void

    80 feed_data (GstElement * appsrc, guint size, App * app)

    81 {

    82   GstBuffer *buffer;

    83   guint len;

    84   GstFlowReturn ret;

    85 

    86   buffer = gst_buffer_new ();

    87 

    88   if (app->offset >= app->length) {

    89     /* we are EOS, send end-of-stream */

    90     g_signal_emit_by_name (app->appsrc, "end-of-stream", &ret);

    91     return;

    92   }

    93 

    94   /* read the next chunk */

    95   len = CHUNK_SIZE;

    96   if (app->offset + len > app->length)

    97     len = app->length - app->offset;

    98 

    99   GST_BUFFER_DATA (buffer) = app->data + app->offset;

   100   GST_BUFFER_SIZE (buffer) = len;

   101 

   102   GST_DEBUG ("feed buffer %p, offset %" G_GUINT64_FORMAT "-%u", buffer,

   103       app->offset, len);

   104   g_signal_emit_by_name (app->appsrc, "push-buffer", buffer, &ret);

   105   gst_buffer_unref (buffer);

   106 

   107   app->offset += len;

   108 

   109   return;

   110 }

   111 

   112 /* this callback is called when playbin2 has constructed a source object to read

   113  * from. Since we provided the appsrc:// uri to playbin2, this will be the

   114  * appsrc that we must handle. We set up a signals to push data into appsrc. */

   115 static void

   116 found_source (GObject * object, GObject * orig, GParamSpec * pspec, App * app)

   117 {

   118   /* get a handle to the appsrc */

   119   g_object_get (orig, pspec->name, &app->appsrc, NULL);

   120 

   121   GST_DEBUG ("got appsrc %p", app->appsrc);

   122 

   123   /* we can set the length in appsrc. This allows some elements to estimate the

   124    * total duration of the stream. It's a good idea to set the property when you

   125    * can but it's not required. */

   126   g_object_set (app->appsrc, "size", (gint64) app->length, NULL);

   127 

   128   /* configure the appsrc, we will push a buffer to appsrc when it needs more

   129    * data */

   130   g_signal_connect (app->appsrc, "need-data", G_CALLBACK (feed_data), app);

   131 }

   132 

   133 static gboolean

   134 bus_message (GstBus * bus, GstMessage * message, App * app)

   135 {

   136   GST_DEBUG ("got message %s",

   137       gst_message_type_get_name (GST_MESSAGE_TYPE (message)));

   138 

   139   switch (GST_MESSAGE_TYPE (message)) {

   140     case GST_MESSAGE_ERROR:

   141       g_error ("received error");

   142       g_main_loop_quit (app->loop);

   143       break;

   144     case GST_MESSAGE_EOS:

   145       g_main_loop_quit (app->loop);

   146       break;

   147     default:

   148       break;

   149   }

   150   return TRUE;

   151 }

   152 

   153 int

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

   155 {

   156   App *app = &s_app;

   157   GError *error = NULL;

   158   GstBus *bus;

   159 

   160   gst_init (&argc, &argv);

   161 

   162   GST_DEBUG_CATEGORY_INIT (appsrc_playbin_debug, "appsrc-playbin", 0,

   163       "appsrc playbin example");

   164 

   165   if (argc < 2) {

   166     g_print ("usage: %s <filename>\n", argv[0]);

   167     return -1;

   168   }

   169 

   170   /* try to open the file as an mmapped file */

   171   app->file = g_mapped_file_new (argv[1], FALSE, &error);

   172   if (error) {

   173     g_print ("failed to open file: %s\n", error->message);

   174     g_error_free (error);

   175     return -2;

   176   }

   177   /* get some vitals, this will be used to read data from the mmapped file and

   178    * feed it to appsrc. */

   179   app->length = g_mapped_file_get_length (app->file);

   180   app->data = (guint8 *) g_mapped_file_get_contents (app->file);

   181   app->offset = 0;

   182 

   183   /* create a mainloop to get messages */

   184   app->loop = g_main_loop_new (NULL, TRUE);

   185 

   186   app->playbin = gst_element_factory_make ("playbin2", NULL);

   187   g_assert (app->playbin);

   188 

   189   bus = gst_pipeline_get_bus (GST_PIPELINE (app->playbin));

   190 

   191   /* add watch for messages */

   192   gst_bus_add_watch (bus, (GstBusFunc) bus_message, app);

   193 

   194   /* set to read from appsrc */

   195   g_object_set (app->playbin, "uri", "appsrc://", NULL);

   196 

   197   /* get notification when the source is created so that we get a handle to it

   198    * and can configure it */

   199   g_signal_connect (app->playbin, "deep-notify::source",

   200       (GCallback) found_source, app);

   201 

   202   /* go to playing and wait in a mainloop. */

   203   gst_element_set_state (app->playbin, GST_STATE_PLAYING);

   204 

   205   /* this mainloop is stopped when we receive an error or EOS */

   206   g_main_loop_run (app->loop);

   207 

   208   GST_DEBUG ("stopping");

   209 

   210   gst_element_set_state (app->playbin, GST_STATE_NULL);

   211 

   212   /* free the file */

   213   g_mapped_file_free (app->file);

   214 

   215   gst_object_unref (bus);

   216   g_main_loop_unref (app->loop);

   217 

   218   return 0;

   219 }