qml6glsrc: sync on the streaming thread

After rendering a QML scene the qml6glsrc element copies the contents of
the scene to a GStreamer buffer. This happens on the Qt render thread.
Then it attaches a sync point to the destination buffer. This sync point
must be awaited by other threads which use the buffer later on. The
current implementation relies on the downstream elements to wait for the
sync point. However, there are situation where this does not work. The
GstBaseTransform e.g. copies the buffer metadata (which overwrites the
sync point without waiting for it) *before* waiting for the sync point.

This commit waits for the sync point inside the qml6glsrc element before
sending it downstream. The wait command is issued on the streaming
thread with the pipeline OpenGL context, i.e. it will synchronize with
the GStreamer OpenGL thread.

This is a port of the original fix for the qmlglsrc element.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5519>
This commit is contained in:
Matthias Fuchs 2023-10-20 08:14:40 +02:00 committed by GStreamer Marge Bot
parent 9f3b8c9366
commit 2bbc2a4c52

View file

@ -436,6 +436,8 @@ gst_qml6_gl_src_create (GstPushSrc * psrc, GstBuffer ** buffer)
{
GstQml6GLSrc *qt_src = GST_QML6_GL_SRC (psrc);
GstCaps *updated_caps = NULL;
GstGLContext* context = qt_src->context;
GstGLSyncMeta *sync_meta;
*buffer = qt6_gl_window_take_buffer (qt_src->window, &updated_caps);
GST_DEBUG_OBJECT (qt_src, "produced buffer %p", *buffer);
@ -448,6 +450,10 @@ gst_qml6_gl_src_create (GstPushSrc * psrc, GstBuffer ** buffer)
}
gst_clear_caps (&updated_caps);
sync_meta = gst_buffer_get_gl_sync_meta(*buffer);
if (sync_meta)
gst_gl_sync_meta_wait(sync_meta, context);
if (!qt_src->downstream_supports_affine_meta) {
if (qt_src->pending_image_orientation) {
/* let downstream know the image orientation is vertical filp */