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examples: overlay: Add an example for Win32 window handle with playbin
Demonstrate video overlay handling on Windows when playbin is in use

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/983>
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seungha-yang committed Dec 20, 2020
1 parent f76b731 commit 932dfd4
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7 changes: 7 additions & 0 deletions tests/examples/overlay/meson.build
Expand Up @@ -43,4 +43,11 @@ if host_system == 'windows'
dependencies : [gst_dep, video_dep],
install: false,
)

executable('win32-videooverlay-playbin', 'win32-videooverlay-playbin.c',
c_args : gst_plugins_base_args,
include_directories : [configinc, libsinc],
dependencies : [gst_dep, video_dep],
install: false,
)
endif
249 changes: 249 additions & 0 deletions tests/examples/overlay/win32-videooverlay-playbin.c
@@ -0,0 +1,249 @@
/*
* GStreamer
* Copyright (C) 2020 Seungha Yang <seungha@centricular.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.
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

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

static GMainLoop *loop = NULL;
static gboolean visible = FALSE;
static HWND hwnd = NULL;
static gboolean set_handle_on_request = FALSE;

static LRESULT CALLBACK
window_proc (HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message) {
case WM_DESTROY:
hwnd = NULL;

if (loop) {
g_main_loop_quit (loop);
}
return 0;
default:
break;
}

return DefWindowProc (hWnd, message, wParam, lParam);
}

static gboolean
msg_cb (GIOChannel * source, GIOCondition condition, gpointer data)
{
MSG msg;

if (!PeekMessage (&msg, NULL, 0, 0, PM_REMOVE))
return G_SOURCE_CONTINUE;

TranslateMessage (&msg);
DispatchMessage (&msg);

return G_SOURCE_CONTINUE;
}

static gboolean
bus_msg (GstBus * bus, GstMessage * msg, gpointer user_data)
{
GstElement *playbin = GST_ELEMENT (user_data);

switch (GST_MESSAGE_TYPE (msg)) {
case GST_MESSAGE_ASYNC_DONE:
/* make window visible when we have something to show */
if (!visible && hwnd) {
ShowWindow (hwnd, SW_SHOW);
visible = TRUE;
}

gst_element_set_state (playbin, GST_STATE_PLAYING);
break;
case GST_MESSAGE_EOS:
gst_println ("End of stream");
g_main_loop_quit (loop);
break;
default:
break;
}

return TRUE;
}

static GstBusSyncReply
bus_sync_handler (GstBus * bus, GstMessage * msg, gpointer user_data)
{
if (set_handle_on_request &&
gst_is_video_overlay_prepare_window_handle_message (msg)) {
GstVideoOverlay *overlay = GST_VIDEO_OVERLAY (GST_MESSAGE_SRC (msg));

gst_println ("Pipeline needs window handle");
gst_video_overlay_set_window_handle (overlay, (guintptr) hwnd);
gst_message_unref (msg);

return GST_BUS_DROP;
}

switch (GST_MESSAGE_TYPE (msg)) {
case GST_MESSAGE_ERROR:{
GError *err;
gchar *dbg;

gst_message_parse_error (msg, &err, &dbg);
gst_printerrln ("ERROR %s ", err->message);
if (dbg != NULL)
gst_printerrln ("ERROR debug information: %s", dbg);
g_clear_error (&err);
g_free (dbg);

g_main_loop_quit (loop);
break;
}
default:
break;
}

return GST_BUS_PASS;
}

gint
main (gint argc, gchar ** argv)
{
GstElement *playbin;
WNDCLASSEX wc = { 0, };
HINSTANCE hinstance = GetModuleHandle (NULL);
GIOChannel *msg_io_channel;
GOptionContext *option_ctx;
GError *error = NULL;
gchar *uri = NULL;
RECT wr = { 0, 0, 320, 240 };
gint exitcode = 0;
gboolean ret;
GOptionEntry options[] = {
{"uri", 0, 0, G_OPTION_ARG_STRING, &uri,
"URI to test playback with Win32 overlay", NULL}
,
{"set-handle-on-request", 0, 0, G_OPTION_ARG_NONE, &set_handle_on_request,
"Set window handle on \"prepare-window-handle\" message", NULL}
,
{NULL}
};

option_ctx =
g_option_context_new ("WIN32 video overlay with playbin example");
g_option_context_add_main_entries (option_ctx, options, NULL);
g_option_context_add_group (option_ctx, gst_init_get_option_group ());
ret = g_option_context_parse (option_ctx, &argc, &argv, &error);
g_option_context_free (option_ctx);

if (!ret) {
gst_printerrln ("option parsing failed: %s", error->message);
g_clear_error (&error);
exit (1);
}

if (!uri) {
gst_printerrln ("--uri is a required argument");
g_clear_error (&error);
exit (1);
}

/* prepare window */
wc.cbSize = sizeof (WNDCLASSEX);
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = (WNDPROC) window_proc;
wc.hInstance = hinstance;
wc.hCursor = LoadCursor (NULL, IDC_ARROW);
wc.lpszClassName = "GstWin32VideoOverlayPlaybin";
RegisterClassEx (&wc);

AdjustWindowRect (&wr, WS_OVERLAPPEDWINDOW, FALSE);
hwnd = CreateWindowEx (0, wc.lpszClassName,
"GstWin32VideoOverlayPlaybin",
WS_CLIPSIBLINGS | WS_CLIPCHILDREN | WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT,
wr.right - wr.left, wr.bottom - wr.top, (HWND) NULL, (HMENU) NULL,
hinstance, NULL);

loop = g_main_loop_new (NULL, FALSE);
msg_io_channel = g_io_channel_win32_new_messages (0);
g_io_add_watch (msg_io_channel, G_IO_IN, msg_cb, NULL);

/* prepare the pipeline */
playbin = gst_element_factory_make ("playbin", NULL);

if (!playbin) {
gst_printerrln ("playbin is not available");

exitcode = 1;
goto terminate;
}

/* User can set window handle on playbin before starting
* pipeline without watching "prepare-window-handle" message,
* because playbin/playsink will pass the given handle to selected
* video sink element later once video sink is prepared.
*
* But in case that an application wants to delay setting window handle
* as much as possible for some reason, the application needs to check
* "prepare-window-handle" message
* (use gst_is_video_overlay_prepare_window_handle_message() API for check)
* via a *sync* message handler and should set window handle on
* the *sync* message handler immediately */
if (!set_handle_on_request) {
GstVideoOverlay *overlay = GST_VIDEO_OVERLAY (playbin);

gst_println ("Setting window handle now");
gst_video_overlay_set_window_handle (overlay, (guintptr) hwnd);
} else {
gst_println ("Will set window handle on \"prepare-window-handle\" message");
}

g_object_set (playbin, "uri", uri, NULL);
gst_bus_set_sync_handler (GST_ELEMENT_BUS (playbin),
bus_sync_handler, NULL, NULL);
gst_bus_add_watch (GST_ELEMENT_BUS (playbin), bus_msg, playbin);

if (gst_element_set_state (playbin,
GST_STATE_PAUSED) == GST_STATE_CHANGE_FAILURE) {
gst_printerrln ("Pipeline doesn't want to pause");
gst_bus_remove_watch (GST_ELEMENT_BUS (playbin));

exitcode = 1;
goto terminate;
}

g_main_loop_run (loop);
gst_element_set_state (playbin, GST_STATE_NULL);
gst_bus_remove_watch (GST_ELEMENT_BUS (playbin));

terminate:
if (hwnd)
DestroyWindow (hwnd);

gst_object_unref (playbin);
g_io_channel_unref (msg_io_channel);
g_main_loop_unref (loop);
g_free (uri);

return exitcode;
}

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