[pitivi] pipeline: Avoid committing the timeline while rendering

[Thibault Saunier <tsaunier src gnome org>]

commit 97f1b5a9bc4aaa84a9a5eb5b88a47bab8865ddd5
Author: Thibault Saunier <tsaunier igalia com>
Date:   Mon Jan 11 17:50:26 2021 -0300

    pipeline: Avoid committing the timeline while rendering
    
    This can cause weird behavior and in particular it can lead to
    de-synchronized audio/video streams.
    
    Fixes https://gitlab.gnome.org/GNOME/pitivi/-/issues/2498

 pitivi/editorperspective.py | 3 +++
 pitivi/utils/pipeline.py    | 8 ++++----
 2 files changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/pitivi/editorperspective.py b/pitivi/editorperspective.py
index a25450cd3..49cbf6138 100644
--- a/pitivi/editorperspective.py
+++ b/pitivi/editorperspective.py
@@ -128,6 +128,9 @@ class EditorPerspective(Perspective, Loggable):
             # Nothing to work with, Pitivi is starting up.
             return
 
+        if self.app.project_manager.current_project.pipeline.rendering():
+            return
+
         # Commit the timeline so its nested timelines assets are refreshed.
         ges_timeline.commit()
 
diff --git a/pitivi/utils/pipeline.py b/pitivi/utils/pipeline.py
index 857f46f21..d389ba906 100644
--- a/pitivi/utils/pipeline.py
+++ b/pitivi/utils/pipeline.py
@@ -424,7 +424,7 @@ class SimplePipeline(GObject.Object, Loggable):
             Gst.debug_bin_to_dot_file_with_ts(self._pipeline,
                                               Gst.DebugGraphDetails.ALL,
                                               "pitivi.error")
-            if not self._rendering():
+            if not self.rendering():
                 self._remove_waiting_for_async_done_timeout()
                 self._recover()
         elif message.type == Gst.MessageType.DURATION_CHANGED:
@@ -498,7 +498,7 @@ class SimplePipeline(GObject.Object, Loggable):
             raise PipelineError("Couldn't get duration: Returned None")
         return dur
 
-    def _rendering(self):
+    def rendering(self):
         return False
 
 
@@ -611,7 +611,7 @@ class Pipeline(GES.Pipeline, SimplePipeline):
             # Nowhere to seek.
             return
 
-        if self._rendering():
+        if self.rendering():
             raise PipelineError("Trying to seek while rendering")
 
         st = Gst.Structure.new_empty("seek")
@@ -675,6 +675,6 @@ class Pipeline(GES.Pipeline, SimplePipeline):
             self._was_empty = True
             self._remove_waiting_for_async_done_timeout()
 
-    def _rendering(self):
+    def rendering(self):
         mask = GES.PipelineFlags.RENDER | GES.PipelineFlags.SMART_RENDER
         return self._pipeline.get_mode() & mask != 0