flutter_gstreamer_player/ios/Classes/GStreamerBackend.m

#import "GStreamerBackend.h"

#include <gst/gst.h>
#include <gst/video/video.h>

GST_DEBUG_CATEGORY_STATIC (debug_category);
#define GST_CAT_DEFAULT debug_category

@interface GStreamerBackend()
-(void)setUIMessage:(gchar*) message;
-(void)app_function:(gchar*) pipeline_string;
-(void)check_initialization_complete;
@end

@implementation GStreamerBackend {
    /* id ui_delegate;        /1* Class that we use to interact with the user interface *1/ */
    GstElement *pipeline;  /* The running pipeline */
    GstElement *video_sink;/* The video sink element which receives XOverlay commands */
    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 */
    UIView *ui_video_view; /* UIView that holds the video */
}

-(id) init:(NSString*) pipeline videoView:(UIView*) video_view
{
    if (self = [super init])
    {
        /* self->ui_delegate = uiDelegate; */
        self->ui_video_view = video_view;

        GST_DEBUG_CATEGORY_INIT (debug_category, "tutorial-3", 0, "iOS tutorial 3");
        gst_debug_set_threshold_for_name("tutorial-3", GST_LEVEL_DEBUG);

        /* Start the bus monitoring task */
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
            [self app_function: (gchar*)[pipeline UTF8String]];
        });
    }

    return self;
}

-(void) dealloc
{
    if (pipeline) {
        NSLog(@"Setting the pipeline to NULL");
        gst_element_set_state(pipeline, GST_STATE_NULL);
        gst_object_unref(pipeline);
        pipeline = NULL;
    }
}

/*
 * 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) {
        NSLog (@"Initialization complete, notifying application.");
        /* if (ui_delegate && [ui_delegate respondsToSelector:@selector(gstreamerInitialized)]) */
        /* { */
        /*     [ui_delegate gstreamerInitialized]; */
        /* } */
        initialized = TRUE;

        NSLog(@"Initialization complete, notifying application.");
        if(gst_element_set_state(pipeline, GST_STATE_PLAYING) == GST_STATE_CHANGE_FAILURE) {
            [self setUIMessage:"Failed to set pipeline to playing"];
        }
    }
}

/* Main method for the bus monitoring code */
-(void) app_function:(gchar*) pipeline_string
{
    GstBus *bus;
    GSource *bus_source;
    GError *error = NULL;

    NSLog (@"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("videotestsrc ! warptv ! videoconvert ! autovideosink", &error); */
    /* pipeline = gst_parse_launch("rtspsrc location= \ */
    /*                         rtsp://wowzaec2demo.streamlock.net/vod/mp4:BigBuckBunny_115k.mp4 latency=0 ! \ */
    /*                       decodebin ! \ */
    /*                       autovideosink", &error); */
    NSLog(@"Pipeline 1: %s", pipeline_string);
    NSLog(@"Pipeline 2: %s", pipeline_string);
    pipeline = gst_parse_launch(pipeline_string, &error);
    if (error) {
        NSLog (@"Unable to build pipeline: %s", error->message);
        gchar *message = g_strdup_printf("Unable to build pipeline: %s", error->message);
        g_clear_error (&error);
        [self setUIMessage:message];
        g_free (message);
        return;
    }

    /* Set the pipeline to READY, so it can already accept a window handle */
    gst_element_set_state(pipeline, GST_STATE_READY);

    video_sink = gst_bin_get_by_interface(GST_BIN(pipeline), GST_TYPE_VIDEO_OVERLAY);
    if (!video_sink) {
        NSLog (@"Could not retrieve video sink");
        return;
    }
    gst_video_overlay_set_window_handle(GST_VIDEO_OVERLAY(video_sink), (guintptr) (id) ui_video_view);

    /* 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 */
    NSLog (@"Entering main loop...");
    main_loop = g_main_loop_new (context, FALSE);
    [self check_initialization_complete];
    g_main_loop_run (main_loop);
    NSLog (@"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