gstreamer/tests/examples/dynamic/codec-select.c

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/* GStreamer
*
* codec-select.c: sample application to dynamically select a codec
*
* Copyright (C) <2008> Wim Taymans <wim dot taymans at gmail dot com>
*
* 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
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* 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.
*/
/*
* This example sets up a pipeline to 'encode' an audiotestsrc into 3 different
* formats. The format can be selected dynamically at runtime.
*
* Each of the encoders require the audio in a specific different format.
*
* This example uses identity as the encoder and enforces the caps on identity
* with a capsfilter.
*
* This is a good example of input and output selector and how these elements
* preserve segment and timing information while switching between streams.
*/
#include <string.h>
#include <gst/gst.h>
/* Create an encoder element.
* We make a bin containing:
*
* audioresample ! <enccaps> ! identity
*
* The sinkpad of audioresample and source pad of identity are ghosted on the
* bin.
*/
static GstElement *
make_encoder (const GstCaps * caps)
{
GstElement *result;
GstElement *audioresample;
GstElement *capsfilter;
GstElement *identity;
GstPad *pad;
/* create result bin */
result = gst_bin_new (NULL);
g_assert (result);
/* create elements */
audioresample = gst_element_factory_make ("audioresample", NULL);
g_assert (audioresample);
capsfilter = gst_element_factory_make ("capsfilter", NULL);
g_assert (capsfilter);
g_object_set (capsfilter, "caps", caps, NULL);
identity = gst_element_factory_make ("identity", NULL);
g_assert (identity);
g_object_set (identity, "silent", TRUE, NULL);
/* add elements to result bin */
gst_bin_add (GST_BIN (result), audioresample);
gst_bin_add (GST_BIN (result), capsfilter);
gst_bin_add (GST_BIN (result), identity);
/* link elements */
gst_element_link_pads (audioresample, "src", capsfilter, "sink");
gst_element_link_pads (capsfilter, "src", identity, "sink");
/* ghost src and sink pads */
pad = gst_element_get_static_pad (audioresample, "sink");
gst_element_add_pad (result, gst_ghost_pad_new ("sink", pad));
gst_object_unref (pad);
pad = gst_element_get_static_pad (identity, "src");
gst_element_add_pad (result, gst_ghost_pad_new ("src", pad));
gst_object_unref (pad);
return result;
}
/*
* We generate:
*
* audiotestsrc ! <audiocaps> ! output-selector ! [enc1 .. enc3] ! input-selector
* select-all = true ! fakesink
*
* <audiocaps> makes sure we only produce one format from the audiotestsrc.
*
* Each encX element consists of:
*
* audioresample ! <enccaps> ! identity !
*
* This way we can simply switch encoders without having to renegotiate.
*/
static GstElement *
make_pipeline (void)
{
GstElement *result;
GstElement *audiotestsrc;
GstElement *audiocaps;
GstElement *outputselect;
GstElement *inputselect;
GstElement *sink;
GstCaps *caps;
GstCaps *capslist[3];
gint i;
/* create result pipeline */
result = gst_pipeline_new (NULL);
g_assert (result);
/* create various elements */
audiotestsrc = gst_element_factory_make ("audiotestsrc", NULL);
g_object_set (audiotestsrc, "num-buffers", 1000, NULL);
g_assert (audiotestsrc);
audiocaps = gst_element_factory_make ("capsfilter", NULL);
g_assert (audiocaps);
caps =
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gst_caps_from_string ("audio/x-raw,format=S16LE,rate=48000,channels=1");
g_object_set (audiocaps, "caps", caps, NULL);
gst_caps_unref (caps);
outputselect = gst_element_factory_make ("output-selector", "select");
g_assert (outputselect);
inputselect = gst_element_factory_make ("input-selector", NULL);
g_assert (inputselect);
g_object_set (inputselect, "select-all", TRUE, NULL);
sink = gst_element_factory_make ("fakesink", NULL);
g_object_set (sink, "sync", TRUE, NULL);
g_object_set (sink, "silent", TRUE, NULL);
g_assert (sink);
/* add elements */
gst_bin_add (GST_BIN (result), audiotestsrc);
gst_bin_add (GST_BIN (result), audiocaps);
gst_bin_add (GST_BIN (result), outputselect);
gst_bin_add (GST_BIN (result), inputselect);
gst_bin_add (GST_BIN (result), sink);
/* link elements */
gst_element_link_pads (audiotestsrc, "src", audiocaps, "sink");
gst_element_link_pads (audiocaps, "src", outputselect, "sink");
gst_element_link_pads (inputselect, "src", sink, "sink");
/* make caps */
capslist[0] =
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gst_caps_from_string ("audio/x-raw,format=S16LE,rate=48000,channels=1");
capslist[1] =
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gst_caps_from_string ("audio/x-raw,format=S16LE,rate=16000,channels=1");
capslist[2] =
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gst_caps_from_string ("audio/x-raw,format=S16LE,rate=8000,channels=1");
/* create encoder elements */
for (i = 0; i < 3; i++) {
GstElement *encoder;
GstPad *srcpad, *sinkpad;
encoder = make_encoder (capslist[i]);
g_assert (encoder);
gst_bin_add (GST_BIN (result), encoder);
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srcpad = gst_element_get_request_pad (outputselect, "src_%u");
sinkpad = gst_element_get_static_pad (encoder, "sink");
gst_pad_link (srcpad, sinkpad);
gst_object_unref (srcpad);
gst_object_unref (sinkpad);
srcpad = gst_element_get_static_pad (encoder, "src");
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sinkpad = gst_element_get_request_pad (inputselect, "sink_%u");
gst_pad_link (srcpad, sinkpad);
gst_object_unref (srcpad);
gst_object_unref (sinkpad);
}
return result;
}
static gboolean
do_switch (GstElement * pipeline)
{
gint rand;
GstElement *select;
gchar *name;
GstPad *pad;
rand = g_random_int_range (0, 3);
g_print ("switching to %d\n", rand);
/* find the selector */
select = gst_bin_get_by_name (GST_BIN (pipeline), "select");
/* get the named pad */
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name = g_strdup_printf ("src_%u", rand);
pad = gst_element_get_static_pad (select, name);
g_free (name);
/* set the active pad */
g_object_set (select, "active-pad", pad, NULL);
return TRUE;
}
static gboolean
my_bus_callback (GstBus * bus, GstMessage * message, gpointer data)
{
GstElement *sender = (GstElement *) GST_MESSAGE_SRC (message);
const gchar *name = gst_element_get_name (sender);
GMainLoop *loop = (GMainLoop *) data;
g_print ("Got %s message from %s\n", GST_MESSAGE_TYPE_NAME (message), name);
switch (GST_MESSAGE_TYPE (message)) {
case GST_MESSAGE_ERROR:{
GError *err;
gchar *debug;
gst_message_parse_error (message, &err, &debug);
g_print ("Error: %s (%s)\n", err->message, debug);
g_error_free (err);
g_free (debug);
g_main_loop_quit (loop);
break;
}
case GST_MESSAGE_EOS:
/* end-of-stream */
g_main_loop_quit (loop);
break;
default:
/* unhandled message */
break;
}
return TRUE;
}
gint
main (gint argc, gchar * argv[])
{
GstElement *pipeline;
GstBus *bus;
GMainLoop *loop;
/* init GStreamer */
gst_init (&argc, &argv);
loop = g_main_loop_new (NULL, FALSE);
/* set up */
pipeline = make_pipeline ();
g_signal_connect (pipeline, "deep_notify",
G_CALLBACK (gst_object_default_deep_notify), NULL);
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
gst_bus_add_watch (bus, my_bus_callback, loop);
gst_object_unref (bus);
g_print ("Starting pipeline\n");
gst_element_set_state (pipeline, GST_STATE_PLAYING);
/* add a timeout to cycle between the formats */
g_timeout_add (1000, (GSourceFunc) do_switch, pipeline);
/* now run */
g_main_loop_run (loop);
g_print ("Nulling pipeline\n");
/* also clean up */
gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (pipeline);
return 0;
}