1 /* GStreamer

     2  *

     3  * appsrc-ra.c: example for using appsrc in random-access 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 random-access mode. When the

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

    39  * requested size and push it to appsrc.

    40  *

    41  * This is a good example how one would deal with a local file resource.

    42  *

    43  * Appsrc in random-access mode needs seeking support and we must thus connect

    44  * to the seek signal to perform any seeks when requested.

    45  *

    46  * In random-access mode we must set the size of the source material.

    47  */

    48 typedef struct _App App;

    49 

    50 struct _App

    51 {

    52   GstElement *playbin;

    53   GstElement *appsrc;

    54 

    55   GMainLoop *loop;

    56 

    57   GMappedFile *file;

    58   guint8 *data;

    59   gsize length;

    60   guint64 offset;

    61 };

    62 

    63 App s_app;

    64 

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

    66  * appsrc with the requested size.

    67  */

    68 static void

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

    70 {

    71   GstBuffer *buffer;

    72   GstFlowReturn ret;

    73 

    74   buffer = gst_buffer_new ();

    75 

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

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

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

    79     return;

    80   }

    81 

    82   /* read the amount of data, we are allowed to return less if we are EOS */

    83   if (app->offset + size > app->length)

    84     size = app->length - app->offset;

    85 

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

    87   GST_BUFFER_SIZE (buffer) = size;

    88   /* we need to set an offset for random access */

    89   GST_BUFFER_OFFSET (buffer) = app->offset;

    90   GST_BUFFER_OFFSET_END (buffer) = app->offset + size;

    91 

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

    93       app->offset, size);

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

    95   gst_buffer_unref (buffer);

    96 

    97   app->offset += size;

    98 

    99   return;

   100 }

   101 

   102 /* called when appsrc wants us to return data from a new position with the next

   103  * call to push-buffer. */

   104 static gboolean

   105 seek_data (GstElement * appsrc, guint64 position, App * app)

   106 {

   107   GST_DEBUG ("seek to offset %" G_GUINT64_FORMAT, position);

   108   app->offset = position;

   109 

   110   return TRUE;

   111 }

   112 

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

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

   115  * appsrc that we must handle. We set up some signals to push data into appsrc

   116  * and one to perform a seek. */

   117 static void

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

   119 {

   120   /* get a handle to the appsrc */

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

   122 

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

   124 

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

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

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

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

   129   gst_util_set_object_arg (G_OBJECT (app->appsrc), "stream-type",

   130       "random-access");

   131 

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

   133    * data */

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

   135   g_signal_connect (app->appsrc, "seek-data", G_CALLBACK (seek_data), app);

   136 }

   137 

   138 static gboolean

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

   140 {

   141   GST_DEBUG ("got message %s",

   142       gst_message_type_get_name (GST_MESSAGE_TYPE (message)));

   143 

   144   switch (GST_MESSAGE_TYPE (message)) {

   145     case GST_MESSAGE_ERROR:

   146       g_error ("received error");

   147       g_main_loop_quit (app->loop);

   148       break;

   149     case GST_MESSAGE_EOS:

   150       g_main_loop_quit (app->loop);

   151       break;

   152     default:

   153       break;

   154   }

   155   return TRUE;

   156 }

   157 

   158 int

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

   160 {

   161   App *app = &s_app;

   162   GError *error = NULL;

   163   GstBus *bus;

   164 

   165   gst_init (&argc, &argv);

   166 

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

   168       "appsrc playbin example");

   169 

   170   if (argc < 2) {

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

   172     return -1;

   173   }

   174 

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

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

   177   if (error) {

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

   179     g_error_free (error);

   180     return -2;

   181   }

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

   183    * feed it to appsrc. */

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

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

   186   app->offset = 0;

   187 

   188   /* create a mainloop to get messages */

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

   190 

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

   192   g_assert (app->playbin);

   193 

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

   195 

   196   /* add watch for messages */

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

   198 

   199   /* set to read from appsrc */

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

   201 

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

   203    * and can configure it */

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

   205       (GCallback) found_source, app);

   206 

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

   208   gst_element_set_state (app->playbin, GST_STATE_PLAYING);

   209 

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

   211   g_main_loop_run (app->loop);

   212 

   213   GST_DEBUG ("stopping");

   214 

   215   gst_element_set_state (app->playbin, GST_STATE_NULL);

   216 

   217   /* free the file */

   218   g_mapped_file_free (app->file);

   219 

   220   gst_object_unref (bus);

   221   g_main_loop_unref (app->loop);

   222 

   223   return 0;

   224 }