[gst-devel] Play audio from a memory buffer?
bcg
bradley.goldsmith at gmail.com
Wed Jan 5 09:48:19 CET 2011
The example:
appsrc-stream.c: example for using appsrc in streaming mode.
Fits the bill. It loads a file as a memory map but if you shoehorn in
your memory location and size at lines:
207 app->length = g_mapped_file_get_length (app->file);
208 app->data = (guint8 *) g_mapped_file_get_contents (app->file);
You'll have a working example of what I was after.
Cheers,
Brad
1 /* GStreamer
2 *
3 * appsrc-stream.c: example for using appsrc in streaming mode.
4 *
5 * Copyright (C) 2008 Wim Taymans <wim.taymans at 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 if (ret != GST_FLOW_OK) {
106 /* some error, stop sending data */
107 return FALSE;
108 }
109
110 app->offset += len;
111
112 return TRUE;
113 }
114
115 /* This signal callback is called when appsrc needs data, we add
an idle handler
116 * to the mainloop to start pushing data into the appsrc */
117 static void
118 start_feed (GstElement * playbin, guint size, App * app)
119 {
120 if (app->sourceid == 0) {
121 GST_DEBUG ("start feeding");
122 app->sourceid = g_idle_add ((GSourceFunc) read_data, app);
123 }
124 }
125
126 /* This callback is called when appsrc has enough data and we can
stop sending.
127 * We remove the idle handler from the mainloop */
128 static void
129 stop_feed (GstElement * playbin, App * app)
130 {
131 if (app->sourceid != 0) {
132 GST_DEBUG ("stop feeding");
133 g_source_remove (app->sourceid);
134 app->sourceid = 0;
135 }
136 }
137
138 /* this callback is called when playbin2 has constructed a source
object to read
139 * from. Since we provided the appsrc:// uri to playbin2, this will be the
140 * appsrc that we must handle. We set up some signals to start
and stop pushing
141 * data into appsrc */
142 static void
143 found_source (GObject * object, GObject * orig, GParamSpec *
pspec, App * app)
144 {
145 /* get a handle to the appsrc */
146 g_object_get (orig, pspec->name, &app->appsrc, NULL);
147
148 GST_DEBUG ("got appsrc %p", app->appsrc);
149
150 /* we can set the length in appsrc. This allows some elements
to estimate the
151 * total duration of the stream. It's a good idea to set the
property when you
152 * can but it's not required. */
153 g_object_set (app->appsrc, "size", app->length, NULL);
154
155 /* configure the appsrc, we will push data into the appsrc from the
156 * mainloop. */
157 g_signal_connect (app->appsrc, "need-data", G_CALLBACK
(start_feed), app);
158 g_signal_connect (app->appsrc, "enough-data", G_CALLBACK
(stop_feed), app);
159 }
160
161 static gboolean
162 bus_message (GstBus * bus, GstMessage * message, App * app)
163 {
164 GST_DEBUG ("got message %s",
165 gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
166
167 switch (GST_MESSAGE_TYPE (message)) {
168 case GST_MESSAGE_ERROR:
169 g_error ("received error");
170 g_main_loop_quit (app->loop);
171 break;
172 case GST_MESSAGE_EOS:
173 g_main_loop_quit (app->loop);
174 break;
175 default:
176 break;
177 }
178 return TRUE;
179 }
180
181 int
182 main (int argc, char *argv[])
183 {
184 App *app = &s_app;
185 GError *error = NULL;
186 GstBus *bus;
187
188 gst_init (&argc, &argv);
189
190 GST_DEBUG_CATEGORY_INIT (appsrc_playbin_debug, "appsrc-playbin", 0,
191 "appsrc playbin example");
192
193 if (argc < 2) {
194 g_print ("usage: %s <filename>\n", argv[0]);
195 return -1;
196 }
197
198 /* try to open the file as an mmapped file */
199 app->file = g_mapped_file_new (argv[1], FALSE, &error);
200 if (error) {
201 g_print ("failed to open file: %s\n", error->message);
202 g_error_free (error);
203 return -2;
204 }
205 /* get some vitals, this will be used to read data from the
mmapped file and
206 * feed it to appsrc. */
207 app->length = g_mapped_file_get_length (app->file);
208 app->data = (guint8 *) g_mapped_file_get_contents (app->file);
209 app->offset = 0;
210
211 /* create a mainloop to get messages and to handle the idle
handler that will
212 * feed data to appsrc. */
213 app->loop = g_main_loop_new (NULL, TRUE);
214
215 app->playbin = gst_element_factory_make ("playbin2", NULL);
216 g_assert (app->playbin);
217
218 bus = gst_pipeline_get_bus (GST_PIPELINE (app->playbin));
219
220 /* add watch for messages */
221 gst_bus_add_watch (bus, (GstBusFunc) bus_message, app);
222
223 /* set to read from appsrc */
224 g_object_set (app->playbin, "uri", "appsrc://", NULL);
225
226 /* get notification when the source is created so that we get a
handle to it
227 * and can configure it */
228 g_signal_connect (app->playbin, "deep-notify::source",
229 (GCallback) found_source, app);
230
231 /* go to playing and wait in a mainloop. */
232 gst_element_set_state (app->playbin, GST_STATE_PLAYING);
233
234 /* this mainloop is stopped when we receive an error or EOS */
235 g_main_loop_run (app->loop);
236
237 GST_DEBUG ("stopping");
238
239 gst_element_set_state (app->playbin, GST_STATE_NULL);
240
241 /* free the file */
242 g_mapped_file_free (app->file);
243
244 gst_object_unref (bus);
245 g_main_loop_unref (app->loop);
246
247 return 0;
248 }
On Wed, Jan 5, 2011 at 5:30 PM, rohitratri at gmail.com [via
GStreamer-devel] <ml-node+3174884-1621197215-207298 at n4.nabble.com>
wrote:
> It can be put in the pipeline. But you need to pump data into it from your
> application. Your application would be (sort of) the 'source' and appsrc is
> like a cheat code to make the following elements think that there is
> actually a source element in there at the start of the pipeline feeding them
> gstbuffers.
> Try looking up the output format of filesrc element and package your data
> similarly and feed it to appsrc. Rest will be taken care by the
> bin/pipeline.
> Rohit
> On Wed, Jan 5, 2011 at 11:34 AM, Brad Goldsmith <[hidden email]> wrote:
>>
>> Can appsrc be put in that pipeline, in place of filesrc, without any
>> additional elements?
>>
>> Cheers,
>> Brad
>>
>> On Wed, Jan 5, 2011 at 1:55 AM, Tim-Philipp Müller <[hidden email]> wrote:
>> > On Tue, 2011-01-04 at 04:35 -0800, bcg wrote:
>> >
>> > Hi,
>> >
>> >> This should almost be an FAQ but it's not in there so here goes:
>> >>
>> >> I have a pipeline thus:
>> >>
>> >> file-source -> decodebin -> audioresample -> converter -> audio_output
>> >>
>> >> Using location (or fd if I change file_source to a fdsrc) I can happily
>> >> play
>> >> most audio I throw at it (including mp3s) providing its in a file. What
>> >> I
>> >> would like to do is play from a memory location with the mp3 data
>> >> already in
>> >> it.
>> >>
>> >> I am assuming I would need to use a fakesrc with a callback to get my
>> >> data
>> >> into the pipeline - I've tried lots of variations on this and gotten
>> >> nowhere.
>> >>
>> >> Can I just replace the file-source with the fakesrc, load the data and
>> >> go
>> >> (if this is possible couple someone provide an example)? Or do I have
>> >> to
>> >> worry about queues and caps? If so, can someone provide an example?
>> >> Will
>> >> decodebin suffice or will I have to be more specific?
>> >
>> > Use appsrc.
>> >
>> > Cheers
>> > -Tim
>> >
>> >
>> >
>> >
>> > ------------------------------------------------------------------------------
>> > Learn how Oracle Real Application Clusters (RAC) One Node allows
>> > customers
>> > to consolidate database storage, standardize their database environment,
>> > and,
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>> > without downtime or disruption
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>> >
>>
>>
>> ------------------------------------------------------------------------------
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>> to consolidate database storage, standardize their database environment,
>> and,
>> should the need arise, upgrade to a full multi-node Oracle RAC database
>> without downtime or disruption
>> http://p.sf.net/sfu/oracle-sfdevnl
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>
>
> ------------------------------------------------------------------------------
> Learn how Oracle Real Application Clusters (RAC) One Node allows customers
> to consolidate database storage, standardize their database environment,
> and,
> should the need arise, upgrade to a full multi-node Oracle RAC database
> without downtime or disruption
> http://p.sf.net/sfu/oracle-sfdevnl
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