1 /* GStreamer

     2  *

     3  * appsrc-seekable.c: example for using appsrc in seekable 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 seekable mode. When the

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

    39  * push it to appsrc. We can also use the method as demonstrated in

    40  * appsrc-stream.c, ie. pushing buffers when we can.

    41  *

    42  * This is a good example how one would deal with a remote http server that

    43  * supports range requests.

    44  *

    45  * Appsrc in seekable mode needs seeking support and we must thus connect

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

    47  *

    48  * In seekable mode we should set the size of the source material.

    49  */

    50 typedef struct _App App;

    51 

    52 struct _App

    53 {

    54   GstElement *playbin;

    55   GstElement *appsrc;

    56 

    57   GMainLoop *loop;

    58 

    59   GMappedFile *file;

    60   guint8 *data;

    61   gsize length;

    62   guint64 offset;

    63 };

    64 

    65 App s_app;

    66 

    67 #define CHUNK_SIZE  4096

    68 

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

    70  * appsrc with an arbitrary size.

    71  */

    72 static void

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

    74 {

    75   GstBuffer *buffer;

    76   guint len;

    77   GstFlowReturn ret;

    78 

    79   buffer = gst_buffer_new ();

    80 

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

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

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

    84     return;

    85   }

    86 

    87   /* read any amount of data, we are allowed to return less if we are EOS */

    88   len = CHUNK_SIZE;

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

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

    91 

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

    93   GST_BUFFER_SIZE (buffer) = len;

    94 

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

    96       app->offset, len);

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

    98   gst_buffer_unref (buffer);

    99 

   100   app->offset += len;

   101 

   102   return;

   103 }

   104 

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

   106  * call to push-buffer. */

   107 static gboolean

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

   109 {

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

   111   app->offset = position;

   112 

   113   return TRUE;

   114 }

   115 

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

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

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

   119  * and one to perform a seek. */

   120 static void

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

   122 {

   123   /* get a handle to the appsrc */

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

   125 

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

   127 

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

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

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

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

   132   /* we are seekable in push mode, this means that the element usually pushes

   133    * out buffers of an undefined size and that seeks happen only occasionally

   134    * and only by request of the user. */

   135   gst_util_set_object_arg (G_OBJECT (app->appsrc), "stream-type", "seekable");

   136 

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

   138    * data */

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

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

   141 }

   142 

   143 static gboolean

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

   145 {

   146   GST_DEBUG ("got message %s",

   147       gst_message_type_get_name (GST_MESSAGE_TYPE (message)));

   148 

   149   switch (GST_MESSAGE_TYPE (message)) {

   150     case GST_MESSAGE_ERROR:

   151       g_error ("received error");

   152       g_main_loop_quit (app->loop);

   153       break;

   154     case GST_MESSAGE_EOS:

   155       g_main_loop_quit (app->loop);

   156       break;

   157     default:

   158       break;

   159   }

   160   return TRUE;

   161 }

   162 

   163 int

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

   165 {

   166   App *app = &s_app;

   167   GError *error = NULL;

   168   GstBus *bus;

   169 

   170   gst_init (&argc, &argv);

   171 

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

   173       "appsrc playbin example");

   174 

   175   if (argc < 2) {

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

   177     return -1;

   178   }

   179 

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

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

   182   if (error) {

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

   184     g_error_free (error);

   185     return -2;

   186   }

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

   188    * feed it to appsrc. */

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

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

   191   app->offset = 0;

   192 

   193   /* create a mainloop to get messages */

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

   195 

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

   197   g_assert (app->playbin);

   198 

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

   200 

   201   /* add watch for messages */

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

   203 

   204   /* set to read from appsrc */

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

   206 

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

   208    * and can configure it */

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

   210       (GCallback) found_source, app);

   211 

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

   213   gst_element_set_state (app->playbin, GST_STATE_PLAYING);

   214 

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

   216   g_main_loop_run (app->loop);

   217 

   218   GST_DEBUG ("stopping");

   219 

   220   gst_element_set_state (app->playbin, GST_STATE_NULL);

   221 

   222   /* free the file */

   223   g_mapped_file_free (app->file);

   224 

   225   gst_object_unref (bus);

   226   g_main_loop_unref (app->loop);

   227 

   228   return 0;

   229 }