Mac OSX Cocoa / interface builder example...

[Gerard Toonstra]

Hi all,

I've managed to find some code online that nicely demonstrates the use of osxvideosink and
gstreamer integration into a standard Cocoa Application project, using interface builder and 
normal Xcode tools:

http://blog.angrymango.com/post/2012/01/04/Playing-a-video-using-gstreamer-on-OSX.aspx#comment

This is (eventually) using the osxvideosink and  therefore can be used directly with the streamer 
installation packages that were developed for the mac. CPU usage on 720p video using this play bin 
amounts to 80-100% or so, whereas the movie player gets up to 7-10% or so, probably using 
video acceleration of some kind (or the play bin uses some unnecessary conversions).

I modified the code to use an existing 'frame' (dummy area) where the video is going to be embedded.
It does not resize properly and there are some other issues probably, but it' s a good start.

I think this example is great to show others how to develop players that use osxvideosink and which can integrate
gstreamer in applications built with interface builder, without jumping through 20 hoops to get there.

Please let me know your concerns and what needs to happen before this can be integrated somewhere in the
gstreamer example code.

Rgds,

Gerard



-----------

//
//  AppDelegate.m
//

#import "AppDelegate.h"
#include <gst/gst.h>
#include <gst/interfaces/xoverlay.h>
#import "MainWindow.h"

/* ============================================================= */
/*                                                               */
/*                   gstreamer callbacks                         */
/*                                                               */
/* ============================================================= */
typedef struct context_t {
    void *appDelegate;
    void *viewingArea;
} context_t;

static GMainLoop *loop;

static gboolean bus_call(GstBus *bus, GstMessage *msg, void *user_data)
{
    context_t *context;
    
    switch (GST_MESSAGE_TYPE(msg)) {
        case GST_MESSAGE_EOS: {
            g_message("End-of-stream");
            g_main_loop_quit(loop);
            break;
        }
        case GST_MESSAGE_ERROR: {
            GError *err;
            gst_message_parse_error(msg, &err, NULL);
            g_error("%s", err->message);
            g_error_free(err);
            
            g_main_loop_quit(loop);
            break;
        }
        default:
            context = (context_t *)user_data;
            if (gst_structure_has_name(msg->structure, "have-ns-view")) {
                NSView* myView = (__bridge NSView*)g_value_get_pointer(gst_structure_get_value(msg->structure, "nsview"));
                AppDelegate* del = (__bridge AppDelegate*)context->appDelegate;
                NSRect viewFrame = [(__bridge NSView*)context->viewingArea frame];
                [[del.window contentView] addSubview:myView];
                [myView setFrame: viewFrame];
                [myView setNeedsDisplay:YES];
                //[del.window setContentView: myWindow];
            }
            
            break;
    }
    
    return true;
}

static void gst_finish(GstElement* object, gpointer user_data)
{
    //set uri to the next clip
}

static void play_uri(const char *uri, void *user_data)
{
    GstElement *pipeline;
    GstBus *bus;
    
    loop = g_main_loop_new(NULL, FALSE);
    pipeline = gst_element_factory_make("playbin2", "player");
    
    if (uri)
        g_object_set(G_OBJECT(pipeline), "uri", uri, NULL);
    
    bus = gst_pipeline_get_bus(GST_PIPELINE(pipeline));
    gst_bus_add_watch(bus, bus_call, user_data);
    gst_object_unref(bus);
    
    g_signal_connect(pipeline, "about-to-finish", G_CALLBACK(gst_finish), user_data);
    
    gst_element_set_state(GST_ELEMENT(pipeline), GST_STATE_PLAYING);
    
    g_main_loop_run(loop);
    
    gst_element_set_state(GST_ELEMENT(pipeline), GST_STATE_NULL);
    gst_object_unref(GST_OBJECT(pipeline));
}

@implementation AppDelegate
@synthesize videoView = _videoView;
@synthesize window = _window;

-(void)g_init:(id)param
{
    gst_init(NULL, NULL);
    context_t *context = malloc(sizeof(context_t));
    context->appDelegate = (__bridge void*)self;
    context->viewingArea = (__bridge void*)_videoView;
    play_uri("file:///Users/Shared/movies/holiday.mp4", context);
}

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    NSThread *g_thread = [[NSThread alloc] initWithTarget:self selector:@selector(g_init:) object:nil];
    [g_thread start];
}

@end
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