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sdlshare2: Fix race conditions

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The client-draw callback is running on the GL Thread, which will
be required to map the buffer. Map early, and pass the mapped
frame instead. On top of that, make sure to signal any pending
draw before trying to push EOS, as some pad locks might be taken.
This is the cost of using the same thread to control GStreamer and
to render GL.
This commit is contained in:
Nicolas Dufresne 2017-11-24 16:58:21 -05:00
parent c9e755d79e
commit 4f36f75eb1
1 changed files with 42 additions and 24 deletions
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66
tests/examples/gl/sdl/sdlshare2.c
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@ -66,13 +66,9 @@ InitGL (int Width, int Height) // We call this right after our OpenGL window is
/* The main drawing function. */
static void
DrawGLScene (GstSample * sample)
DrawGLScene (GstVideoFrame * v_frame)
{
GstVideoFrame v_frame;
GstVideoInfo v_info;
guint texture = 0;
GstBuffer *buf = gst_sample_get_buffer (sample);
GstCaps *caps = gst_sample_get_caps (sample);
#ifdef WIN32
if (!wglGetCurrentContext ())
@ -82,14 +78,7 @@ DrawGLScene (GstSample * sample)
return;
#endif
gst_video_info_from_caps (&v_info, caps);
if (!gst_video_frame_map (&v_frame, &v_info, buf, GST_MAP_READ | GST_MAP_GL)) {
g_warning ("Failed to map the video buffer");
return;
}
texture = *(guint *) v_frame.data[0];
texture = *(guint *) v_frame->data[0];
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
glLoadIdentity (); // Reset The View
@ -139,8 +128,21 @@ DrawGLScene (GstSample * sample)
// swap buffers to display, since we're double buffered.
SDL_GL_SwapBuffers ();
}
gst_video_frame_unmap (&v_frame);
static GMutex app_lock;
static GCond app_cond;
static gboolean app_rendered = FALSE;
static gboolean app_quit = FALSE;
static void
stop_pipeline (GstElement * pipeline)
{
g_mutex_lock (&app_lock);
app_quit = TRUE;
g_cond_signal (&app_cond);
g_mutex_unlock (&app_lock);
gst_element_send_event (pipeline, gst_event_new_eos ());
}
static gboolean
@ -151,12 +153,12 @@ update_sdl_scene (gpointer data)
while (SDL_PollEvent (&event)) {
if (event.type == SDL_QUIT) {
gst_element_send_event (GST_ELEMENT (pipeline), gst_event_new_eos ());
stop_pipeline (pipeline);
return FALSE;
}
if (event.type == SDL_KEYDOWN) {
if (event.key.keysym.sym == SDLK_ESCAPE) {
gst_element_send_event (GST_ELEMENT (pipeline), gst_event_new_eos ());
stop_pipeline (pipeline);
return FALSE;
}
}
@ -165,18 +167,15 @@ update_sdl_scene (gpointer data)
return TRUE;
}
static GMutex app_lock;
static GCond app_cond;
static gboolean
executeCallback (gpointer data)
{
GstSample *sample = (GstSample *) data;
g_mutex_lock (&app_lock);
DrawGLScene (sample);
if (!app_quit)
DrawGLScene (data);
app_rendered = TRUE;
g_cond_signal (&app_cond);
g_mutex_unlock (&app_lock);
@ -187,12 +186,31 @@ static gboolean
on_client_draw (GstElement * glsink, GstGLContext * context, GstSample * sample,
gpointer data)
{
GstBuffer *buf = gst_sample_get_buffer (sample);
GstCaps *caps = gst_sample_get_caps (sample);
GstVideoFrame v_frame;
GstVideoInfo v_info;
/* FIXME don't do that every frame */
gst_video_info_from_caps (&v_info, caps);
if (!gst_video_frame_map (&v_frame, &v_info, buf, GST_MAP_READ | GST_MAP_GL)) {
g_warning ("Failed to map the video buffer");
return TRUE;
}
g_mutex_lock (&app_lock);
g_idle_add_full (G_PRIORITY_HIGH, executeCallback, sample, NULL);
g_cond_wait (&app_cond, &app_lock);
app_rendered = FALSE;
g_idle_add_full (G_PRIORITY_HIGH, executeCallback, &v_frame, NULL);
while (!app_rendered && !app_quit)
g_cond_wait (&app_cond, &app_lock);
g_mutex_unlock (&app_lock);
gst_video_frame_unmap (&v_frame);
return TRUE;
}