1 /* GStreamer

     2  *

     3  * appsrc-stream.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 push mode. We simply push

    38  * buffers into appsrc. The size of the buffers we push can be any size we

    39  * choose.

    40  *

    41  * This example is very close to how one would deal with a streaming webserver

    42  * that does not support range requests or does not report the total file size.

    43  *

    44  * Some optimisations are done so that we don't push too much data. We connect

    45  * to the need-data and enough-data signals to start/stop sending buffers.

    46  *

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

    48  * have to handle any seek callbacks.

    49  *

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

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

    52  */

    53 typedef struct _App App;

    54 

    55 struct _App

    56 {

    57   GstElement *playbin;

    58   GstElement *appsrc;

    59 

    60   GMainLoop *loop;

    61   guint sourceid;

    62 

    63   GMappedFile *file;

    64   guint8 *data;

    65   gsize length;

    66   guint64 offset;

    67 };

    68 

    69 App s_app;

    70 

    71 #define CHUNK_SIZE  4096

    72 

    73 /* This method is called by the idle GSource in the mainloop. We feed CHUNK_SIZE

    74  * bytes into appsrc.

    75  * The ide handler is added to the mainloop when appsrc requests us to start

    76  * sending data (need-data signal) and is removed when appsrc has enough data

    77  * (enough-data signal).

    78  */

    79 static gboolean

    80 read_data (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 and remove the source */

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

    91     return FALSE;

    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   if (ret != GST_FLOW_OK) {

   107     /* some error, stop sending data */

   108     return FALSE;

   109   }

   110 

   111   app->offset += len;

   112 

   113   return TRUE;

   114 }

   115 

   116 /* This signal callback is called when appsrc needs data, we add an idle handler

   117  * to the mainloop to start pushing data into the appsrc */

   118 static void

   119 start_feed (GstElement * playbin, guint size, App * app)

   120 {

   121   if (app->sourceid == 0) {

   122     GST_DEBUG ("start feeding");

   123     app->sourceid = g_idle_add ((GSourceFunc) read_data, app);

   124   }

   125 }

   126 

   127 /* This callback is called when appsrc has enough data and we can stop sending.

   128  * We remove the idle handler from the mainloop */

   129 static void

   130 stop_feed (GstElement * playbin, App * app)

   131 {

   132   if (app->sourceid != 0) {

   133     GST_DEBUG ("stop feeding");

   134     g_source_remove (app->sourceid);

   135     app->sourceid = 0;

   136   }

   137 }

   138 

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

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

   141  * appsrc that we must handle. We set up some signals to start and stop pushing

   142  * data into appsrc */

   143 static void

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

   145 {

   146   /* get a handle to the appsrc */

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

   148 

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

   150 

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

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

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

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

   155 

   156   /* configure the appsrc, we will push data into the appsrc from the

   157    * mainloop. */

   158   g_signal_connect (app->appsrc, "need-data", G_CALLBACK (start_feed), app);

   159   g_signal_connect (app->appsrc, "enough-data", G_CALLBACK (stop_feed), app);

   160 }

   161 

   162 static gboolean

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

   164 {

   165   GST_DEBUG ("got message %s",

   166       gst_message_type_get_name (GST_MESSAGE_TYPE (message)));

   167 

   168   switch (GST_MESSAGE_TYPE (message)) {

   169     case GST_MESSAGE_ERROR:

   170       g_error ("received error");

   171       g_main_loop_quit (app->loop);

   172       break;

   173     case GST_MESSAGE_EOS:

   174       g_main_loop_quit (app->loop);

   175       break;

   176     default:

   177       break;

   178   }

   179   return TRUE;

   180 }

   181 

   182 int

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

   184 {

   185   App *app = &s_app;

   186   GError *error = NULL;

   187   GstBus *bus;

   188 

   189   gst_init (&argc, &argv);

   190 

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

   192       "appsrc playbin example");

   193 

   194   if (argc < 2) {

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

   196     return -1;

   197   }

   198 

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

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

   201   if (error) {

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

   203     g_error_free (error);

   204     return -2;

   205   }

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

   207    * feed it to appsrc. */

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

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

   210   app->offset = 0;

   211 

   212   /* create a mainloop to get messages and to handle the idle handler that will

   213    * feed data to appsrc. */

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

   215 

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

   217   g_assert (app->playbin);

   218 

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

   220 

   221   /* add watch for messages */

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

   223 

   224   /* set to read from appsrc */

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

   226 

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

   228    * and can configure it */

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

   230       (GCallback) found_source, app);

   231 

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

   233   gst_element_set_state (app->playbin, GST_STATE_PLAYING);

   234 

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

   236   g_main_loop_run (app->loop);

   237 

   238   GST_DEBUG ("stopping");

   239 

   240   gst_element_set_state (app->playbin, GST_STATE_NULL);

   241 

   242   /* free the file */

   243   g_mapped_file_free (app->file);

   244 

   245   gst_object_unref (bus);

   246   g_main_loop_unref (app->loop);

   247 

   248   return 0;

   249 }