gstreamer/examples/tutorials/xcode iOS/Tutorial 2/GStreamerBackend.m

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#import "GStreamerBackend.h"
#include <gst/gst.h>
GST_DEBUG_CATEGORY_STATIC (debug_category);
#define GST_CAT_DEFAULT debug_category
@interface GStreamerBackend()
-(void)setUIMessage:(gchar*) message;
-(void)app_function;
-(void)check_initialization_complete;
@end
@implementation GStreamerBackend {
id ui_delegate; /* Class that we use to interact with the user interface */
GstElement *pipeline; /* The running pipeline */
GMainContext *context; /* GLib context used to run the main loop */
GMainLoop *main_loop; /* GLib main loop */
gboolean initialized; /* To avoid informing the UI multiple times about the initialization */
}
/*
* Interface methods
*/
-(id) init:(id) uiDelegate
{
if (self = [super init])
{
self->ui_delegate = uiDelegate;
GST_DEBUG_CATEGORY_INIT (debug_category, "tutorial-2", 0, "iOS tutorial 2");
gst_debug_set_threshold_for_name("tutorial-2", GST_LEVEL_DEBUG);
/* Start the bus monitoring task */
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self app_function];
});
}
return self;
}
-(void) dealloc
{
if (pipeline) {
GST_DEBUG("Setting the pipeline to NULL");
gst_element_set_state(pipeline, GST_STATE_NULL);
gst_object_unref(pipeline);
pipeline = NULL;
}
}
-(void) play
{
if(gst_element_set_state(pipeline, GST_STATE_PLAYING) == GST_STATE_CHANGE_FAILURE) {
[self setUIMessage:"Failed to set pipeline to playing"];
}
}
-(void) pause
{
if(gst_element_set_state(pipeline, GST_STATE_PAUSED) == GST_STATE_CHANGE_FAILURE) {
[self setUIMessage:"Failed to set pipeline to paused"];
}
}
/*
* Private methods
*/
/* Change the message on the UI through the UI delegate */
-(void)setUIMessage:(gchar*) message
{
NSString *string = [NSString stringWithUTF8String:message];
if(ui_delegate && [ui_delegate respondsToSelector:@selector(gstreamerSetUIMessage:)])
{
[ui_delegate gstreamerSetUIMessage:string];
}
}
/* Retrieve errors from the bus and show them on the UI */
static void error_cb (GstBus *bus, GstMessage *msg, GStreamerBackend *self)
{
GError *err;
gchar *debug_info;
gchar *message_string;
gst_message_parse_error (msg, &err, &debug_info);
message_string = g_strdup_printf ("Error received from element %s: %s", GST_OBJECT_NAME (msg->src), err->message);
g_clear_error (&err);
g_free (debug_info);
[self setUIMessage:message_string];
g_free (message_string);
gst_element_set_state (self->pipeline, GST_STATE_NULL);
}
/* Notify UI about pipeline state changes */
static void state_changed_cb (GstBus *bus, GstMessage *msg, GStreamerBackend *self)
{
GstState old_state, new_state, pending_state;
gst_message_parse_state_changed (msg, &old_state, &new_state, &pending_state);
/* Only pay attention to messages coming from the pipeline, not its children */
if (GST_MESSAGE_SRC (msg) == GST_OBJECT (self->pipeline)) {
gchar *message = g_strdup_printf("State changed to %s", gst_element_state_get_name(new_state));
[self setUIMessage:message];
g_free (message);
}
}
/* Check if all conditions are met to report GStreamer as initialized.
* These conditions will change depending on the application */
-(void) check_initialization_complete
{
if (!initialized && main_loop) {
GST_DEBUG ("Initialization complete, notifying application.");
if (ui_delegate && [ui_delegate respondsToSelector:@selector(gstreamerInitialized)])
{
[ui_delegate gstreamerInitialized];
}
initialized = TRUE;
}
}
/* Main method for the bus monitoring code */
-(void) app_function
{
GstBus *bus;
GSource *bus_source;
GError *error = NULL;
GST_DEBUG ("Creating pipeline");
/* Create our own GLib Main Context and make it the default one */
context = g_main_context_new ();
g_main_context_push_thread_default(context);
/* Build pipeline */
pipeline = gst_parse_launch("audiotestsrc ! audioconvert ! audioresample ! autoaudiosink", &error);
if (error) {
gchar *message = g_strdup_printf("Unable to build pipeline: %s", error->message);
g_clear_error (&error);
[self setUIMessage:message];
g_free (message);
return;
}
/* Instruct the bus to emit signals for each received message, and connect to the interesting signals */
bus = gst_element_get_bus (pipeline);
bus_source = gst_bus_create_watch (bus);
g_source_set_callback (bus_source, (GSourceFunc) gst_bus_async_signal_func, NULL, NULL);
g_source_attach (bus_source, context);
g_source_unref (bus_source);
g_signal_connect (G_OBJECT (bus), "message::error", (GCallback)error_cb, (__bridge void *)self);
g_signal_connect (G_OBJECT (bus), "message::state-changed", (GCallback)state_changed_cb, (__bridge void *)self);
gst_object_unref (bus);
/* Create a GLib Main Loop and set it to run */
GST_DEBUG ("Entering main loop...");
main_loop = g_main_loop_new (context, FALSE);
[self check_initialization_complete];
g_main_loop_run (main_loop);
GST_DEBUG ("Exited main loop");
g_main_loop_unref (main_loop);
main_loop = NULL;
/* Free resources */
g_main_context_pop_thread_default(context);
g_main_context_unref (context);
gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (pipeline);
return;
}
@end