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/* GStreamer
* appsrc-stream.c: example for using appsrc in streaming mode.
* Copyright (C) 2008 Wim Taymans <>
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* Library General Public License for more details.
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
#include "config.h"
#include <gst/gst.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
GST_DEBUG_CATEGORY (appsrc_playbin_debug);
#define GST_CAT_DEFAULT appsrc_playbin_debug
* an example application of using appsrc in streaming push mode. We simply push
* buffers into appsrc. The size of the buffers we push can be any size we
* choose.
* This example is very close to how one would deal with a streaming webserver
* that does not support range requests or does not report the total file size.
* Some optimisations are done so that we don't push too much data. We connect
* to the need-data and enough-data signals to start/stop sending buffers.
* Appsrc in streaming mode (the default) does not support seeking so we don't
* have to handle any seek callbacks.
* Some formats are able to estimate the duration of the media file based on the
* file length (mp3, mpeg,..), others report an unknown length (ogg,..).
typedef struct _App App;
struct _App
GstElement *playbin;
GstElement *appsrc;
GMainLoop *loop;
guint sourceid;
GMappedFile *file;
guint8 *data;
gsize length;
guint64 offset;
App s_app;
#define CHUNK_SIZE 4096
/* This method is called by the idle GSource in the mainloop. We feed CHUNK_SIZE
* bytes into appsrc.
* The ide handler is added to the mainloop when appsrc requests us to start
* sending data (need-data signal) and is removed when appsrc has enough data
* (enough-data signal).
static gboolean
read_data (App * app)
GstBuffer *buffer;
guint len;
GstFlowReturn ret;
if (app->offset >= app->length) {
/* we are EOS, send end-of-stream and remove the source */
g_signal_emit_by_name (app->appsrc, "end-of-stream", &ret);
return FALSE;
/* read the next chunk */
buffer = gst_buffer_new ();
if (app->offset + len > app->length)
len = app->length - app->offset;
gst_buffer_append_memory (buffer,
gst_memory_new_wrapped (GST_MEMORY_FLAG_READONLY,
app->data, app->length, app->offset, len, NULL, NULL));
GST_DEBUG ("feed buffer %p, offset %" G_GUINT64_FORMAT "-%u", buffer,
app->offset, len);
g_signal_emit_by_name (app->appsrc, "push-buffer", buffer, &ret);
gst_buffer_unref (buffer);
if (ret != GST_FLOW_OK) {
/* some error, stop sending data */
return FALSE;
app->offset += len;
return TRUE;
/* This signal callback is called when appsrc needs data, we add an idle handler
* to the mainloop to start pushing data into the appsrc */
static void
start_feed (GstElement * playbin, guint size, App * app)
if (app->sourceid == 0) {
GST_DEBUG ("start feeding");
app->sourceid = g_idle_add ((GSourceFunc) read_data, app);
/* This callback is called when appsrc has enough data and we can stop sending.
* We remove the idle handler from the mainloop */
static void
stop_feed (GstElement * playbin, App * app)
if (app->sourceid != 0) {
GST_DEBUG ("stop feeding");
g_source_remove (app->sourceid);
app->sourceid = 0;
/* this callback is called when playbin has constructed a source object to read
* from. Since we provided the appsrc:// uri to playbin, this will be the
* appsrc that we must handle. We set up some signals to start and stop pushing
* data into appsrc */
static void
found_source (GObject * object, GObject * orig, GParamSpec * pspec, App * app)
/* get a handle to the appsrc */
g_object_get (orig, pspec->name, &app->appsrc, NULL);
GST_DEBUG ("got appsrc %p", app->appsrc);
/* we can set the length in appsrc. This allows some elements to estimate the
* total duration of the stream. It's a good idea to set the property when you
* can but it's not required. */
g_object_set (app->appsrc, "size", (gint64) app->length, NULL);
/* configure the appsrc, we will push data into the appsrc from the
* mainloop. */
g_signal_connect (app->appsrc, "need-data", G_CALLBACK (start_feed), app);
g_signal_connect (app->appsrc, "enough-data", G_CALLBACK (stop_feed), app);
static gboolean
bus_message (GstBus * bus, GstMessage * message, App * app)
GST_DEBUG ("got message %s",
gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
switch (GST_MESSAGE_TYPE (message)) {
g_error ("received error");
g_main_loop_quit (app->loop);
g_main_loop_quit (app->loop);
return TRUE;
main (int argc, char *argv[])
App *app = &s_app;
GError *error = NULL;
GstBus *bus;
gst_init (&argc, &argv);
GST_DEBUG_CATEGORY_INIT (appsrc_playbin_debug, "appsrc-playbin", 0,
"appsrc playbin example");
if (argc < 2) {
g_print ("usage: %s <filename>\n", argv[0]);
return -1;
/* try to open the file as an mmapped file */
app->file = g_mapped_file_new (argv[1], FALSE, &error);
if (error) {
g_print ("failed to open file: %s\n", error->message);
g_error_free (error);
return -2;
/* get some vitals, this will be used to read data from the mmapped file and
* feed it to appsrc. */
app->length = g_mapped_file_get_length (app->file);
app->data = (guint8 *) g_mapped_file_get_contents (app->file);
app->offset = 0;
/* create a mainloop to get messages and to handle the idle handler that will
* feed data to appsrc. */
app->loop = g_main_loop_new (NULL, TRUE);
app->playbin = gst_element_factory_make ("playbin", NULL);
g_assert (app->playbin);
bus = gst_pipeline_get_bus (GST_PIPELINE (app->playbin));
/* add watch for messages */
gst_bus_add_watch (bus, (GstBusFunc) bus_message, app);
/* set to read from appsrc */
g_object_set (app->playbin, "uri", "appsrc://", NULL);
/* get notification when the source is created so that we get a handle to it
* and can configure it */
g_signal_connect (app->playbin, "deep-notify::source",
(GCallback) found_source, app);
/* go to playing and wait in a mainloop. */
gst_element_set_state (app->playbin, GST_STATE_PLAYING);
/* this mainloop is stopped when we receive an error or EOS */
g_main_loop_run (app->loop);
GST_DEBUG ("stopping");
gst_element_set_state (app->playbin, GST_STATE_NULL);
/* free the file */
g_mapped_file_unref (app->file);
gst_object_unref (bus);
g_main_loop_unref (app->loop);
return 0;