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., 51 Franklin St, Fifth Floor,
20 * Boston, MA 02110-1301, 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
feed_data(GstElement * appsrc,guint size,App * app)69 feed_data (GstElement * appsrc, guint size, App * app)
70 {
71 GstBuffer *buffer;
72 GstFlowReturn ret;
73
74 if (app->offset >= app->length) {
75 /* we are EOS, send end-of-stream */
76 g_signal_emit_by_name (app->appsrc, "end-of-stream", &ret);
77 return;
78 }
79
80 /* read the amount of data, we are allowed to return less if we are EOS */
81 buffer = gst_buffer_new ();
82
83 if (app->offset + size > app->length)
84 size = app->length - app->offset;
85
86 gst_buffer_append_memory (buffer,
87 gst_memory_new_wrapped (GST_MEMORY_FLAG_READONLY,
88 app->data, app->length, app->offset, size, NULL, NULL));
89
90 /* we need to set an offset for random access */
91 GST_BUFFER_OFFSET (buffer) = app->offset;
92 GST_BUFFER_OFFSET_END (buffer) = app->offset + size;
93
94 GST_DEBUG ("feed buffer %p, offset %" G_GUINT64_FORMAT "-%u", buffer,
95 app->offset, size);
96 g_signal_emit_by_name (app->appsrc, "push-buffer", buffer, &ret);
97 gst_buffer_unref (buffer);
98
99 app->offset += size;
100
101 return;
102 }
103
104 /* called when appsrc wants us to return data from a new position with the next
105 * call to push-buffer. */
106 static gboolean
seek_data(GstElement * appsrc,guint64 position,App * app)107 seek_data (GstElement * appsrc, guint64 position, App * app)
108 {
109 GST_DEBUG ("seek to offset %" G_GUINT64_FORMAT, position);
110 app->offset = position;
111
112 return TRUE;
113 }
114
115 /* this callback is called when playbin has constructed a source object to read
116 * from. Since we provided the appsrc:// uri to playbin, this will be the
117 * appsrc that we must handle. We set up some signals to push data into appsrc
118 * and one to perform a seek. */
119 static void
found_source(GObject * object,GObject * orig,GParamSpec * pspec,App * app)120 found_source (GObject * object, GObject * orig, GParamSpec * pspec, App * app)
121 {
122 /* get a handle to the appsrc */
123 g_object_get (orig, pspec->name, &app->appsrc, NULL);
124
125 GST_DEBUG ("got appsrc %p", app->appsrc);
126
127 /* we can set the length in appsrc. This allows some elements to estimate the
128 * total duration of the stream. It's a good idea to set the property when you
129 * can but it's not required. */
130 g_object_set (app->appsrc, "size", (gint64) app->length, NULL);
131 gst_util_set_object_arg (G_OBJECT (app->appsrc), "stream-type",
132 "random-access");
133
134 /* configure the appsrc, we will push a buffer to appsrc when it needs more
135 * data */
136 g_signal_connect (app->appsrc, "need-data", G_CALLBACK (feed_data), app);
137 g_signal_connect (app->appsrc, "seek-data", G_CALLBACK (seek_data), app);
138 }
139
140 static gboolean
bus_message(GstBus * bus,GstMessage * message,App * app)141 bus_message (GstBus * bus, GstMessage * message, App * app)
142 {
143 GST_DEBUG ("got message %s",
144 gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
145
146 switch (GST_MESSAGE_TYPE (message)) {
147 case GST_MESSAGE_ERROR:
148 g_error ("received error");
149 g_main_loop_quit (app->loop);
150 break;
151 case GST_MESSAGE_EOS:
152 g_main_loop_quit (app->loop);
153 break;
154 default:
155 break;
156 }
157 return TRUE;
158 }
159
160 int
main(int argc,char * argv[])161 main (int argc, char *argv[])
162 {
163 App *app = &s_app;
164 GError *error = NULL;
165 GstBus *bus;
166
167 gst_init (&argc, &argv);
168
169 GST_DEBUG_CATEGORY_INIT (appsrc_playbin_debug, "appsrc-playbin", 0,
170 "appsrc playbin example");
171
172 if (argc < 2) {
173 g_print ("usage: %s <filename>\n", argv[0]);
174 return -1;
175 }
176
177 /* try to open the file as an mmapped file */
178 app->file = g_mapped_file_new (argv[1], FALSE, &error);
179 if (error) {
180 g_print ("failed to open file: %s\n", error->message);
181 g_error_free (error);
182 return -2;
183 }
184 /* get some vitals, this will be used to read data from the mmapped file and
185 * feed it to appsrc. */
186 app->length = g_mapped_file_get_length (app->file);
187 app->data = (guint8 *) g_mapped_file_get_contents (app->file);
188 app->offset = 0;
189
190 /* create a mainloop to get messages */
191 app->loop = g_main_loop_new (NULL, TRUE);
192
193 app->playbin = gst_element_factory_make ("playbin", NULL);
194 g_assert (app->playbin);
195
196 bus = gst_pipeline_get_bus (GST_PIPELINE (app->playbin));
197
198 /* add watch for messages */
199 gst_bus_add_watch (bus, (GstBusFunc) bus_message, app);
200
201 /* set to read from appsrc */
202 g_object_set (app->playbin, "uri", "appsrc://", NULL);
203
204 /* get notification when the source is created so that we get a handle to it
205 * and can configure it */
206 g_signal_connect (app->playbin, "deep-notify::source",
207 (GCallback) found_source, app);
208
209 /* go to playing and wait in a mainloop. */
210 gst_element_set_state (app->playbin, GST_STATE_PLAYING);
211
212 /* this mainloop is stopped when we receive an error or EOS */
213 g_main_loop_run (app->loop);
214
215 GST_DEBUG ("stopping");
216
217 gst_element_set_state (app->playbin, GST_STATE_NULL);
218
219 /* free the file */
220 g_mapped_file_unref (app->file);
221
222 gst_object_unref (bus);
223 g_main_loop_unref (app->loop);
224
225 return 0;
226 }
227